Excessive pigmentation of the skin, usually as a result of increased epidermal or dermal melanin pigmentation, hypermelanosis. Hyperpigmentation can be localized or generalized. The condition may arise from exposure to light, chemicals or other substances, or from a primary metabolic imbalance.
Disorders of increased melanin pigmentation that develop without preceding inflammatory disease.
Coloration of the skin.
Pigmentation disorders are conditions that affect the production or distribution of melanin, the pigment responsible for skin, hair, and eye color, leading to changes in the color of these bodily features.
Small circumscribed melanoses resembling, but differing histologically from, freckles. The concept includes senile lentigo ('liver spots') and nevoid lentigo (nevus spilus, lentigo simplex) and may also occur in association with multiple congenital defects or congenital syndromes (e.g., Peutz-Jeghers syndrome).
Insoluble polymers of TYROSINE derivatives found in and causing darkness in skin (SKIN PIGMENTATION), hair, and feathers providing protection against SUNBURN induced by SUNLIGHT. CAROTENES contribute yellow and red coloration.
Facial dermatoses refers to various skin conditions that affect the face, causing symptoms such as redness, inflammation, papules, pustules, scaling, or pigmentation changes, which can be caused by a range of factors including genetics, infections, allergies, and environmental factors.
Light brown pigmented macules associated with NEUROFIBROMATOSIS and Albright's syndrome (see FIBROUS DYSPLASIA, POLYOSTOTIC).
Chemicals that are used to oxidize pigments and thus effect whitening.
An enzyme of the oxidoreductase class that catalyzes the reaction between L-tyrosine, L-dopa, and oxygen to yield L-dopa, dopaquinone, and water. It is a copper protein that acts also on catechols, catalyzing some of the same reactions as CATECHOL OXIDASE. EC 1.14.18.1.
Mammalian pigment cells that produce MELANINS, pigments found mainly in the EPIDERMIS, but also in the eyes and the hair, by a process called melanogenesis. Coloration can be altered by the number of melanocytes or the amount of pigment produced and stored in the organelles called MELANOSOMES. The large non-mammalian melanin-containing cells are called MELANOPHORES.
A condition caused by a deficiency or a loss of melanin pigmentation in the epidermis, also known as hypomelanosis. Hypopigmentation can be localized or generalized, and may result from genetic defects, trauma, inflammation, or infections.
Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of causes.
A nonimmunologic, chemically induced type of photosensitivity producing a sometimes vesiculating dermatitis. It results in hyperpigmentation and desquamation of the light-exposed areas of the skin.
A macular lesion on the side of the FACE, involving the CONJUNCTIVA and EYELIDS, as well as the adjacent facial skin, SCLERA; OCULOMOTOR MUSCLES; and PERIOSTEUM. Histological features vary from those of a MONGOLIAN SPOT to those of a BLUE NEVUS.
A common chronic, noninflammatory and usually symptomless disorder, characterized by the occurrence of multiple macular patches of all sizes and shapes, and varying in pigmentation from fawn-colored to brown. It is seen most frequently in hot, humid, tropical regions, and is caused by Pityrosporon orbiculare. (Dorland, 27th ed)
A chronic disorder of the pilosebaceous apparatus associated with an increase in sebum secretion. It is characterized by open comedones (blackheads), closed comedones (whiteheads), and pustular nodules. The cause is unknown, but heredity and age are predisposing factors.
A circumscribed melanosis consisting of a brown-pigmented, velvety verrucosity or fine papillomatosis appearing in the axillae and other body folds. It occurs in association with endocrine disorders, underlying malignancy, administration of certain drugs, or as in inherited disorder.
'Skin diseases' is a broad term for various conditions affecting the skin, including inflammatory disorders, infections, benign and malignant tumors, congenital abnormalities, and degenerative diseases, which can cause symptoms such as rashes, discoloration, eruptions, lesions, itching, or pain.
Common name for the order Pleuronectiformes. A very distinctive group in that during development they become asymmetrical, i.e., one eye migrates to lie adjacent to the other. They swim on the eyeless side. FLOUNDER, sole, and turbot, along with several others, are included in this order.
Abnormal responses to sunlight or artificial light due to extreme reactivity of light-absorbing molecules in tissues. It refers almost exclusively to skin photosensitivity, including sunburn, reactions due to repeated prolonged exposure in the absence of photosensitizing factors, and reactions requiring photosensitizing factors such as photosensitizing agents and certain diseases. With restricted reference to skin tissue, it does not include photosensitivity of the eye to light, as in photophobia or photosensitive epilepsy.
Hydroquinones are chemical compounds that function as potent depigmenting agents, inhibiting the enzymatic conversion of tyrosine to melanin, used topically in the treatment of various dermatological disorders such as melasma, freckles, and hyperpigmentation.
Adverse cutaneous reactions caused by ingestion, parenteral use, or local application of a drug. These may assume various morphologic patterns and produce various types of lesions.
Drugs used to treat or prevent skin disorders or for the routine care of skin.
An extensive order of basidiomycetous fungi whose fruiting bodies are commonly called mushrooms.
A group of disorders characterized by an autosomal dominant pattern of inheritance with high rates of spontaneous mutation and multiple neurofibromas or neurilemmomas. NEUROFIBROMATOSIS 1 (generalized neurofibromatosis) accounts for approximately 95% of cases, although multiple additional subtypes (e.g., NEUROFIBROMATOSIS 2, neurofibromatosis 3, etc.) have been described. (From Neurochirurgie 1998 Nov;44(4):267-72)
Melanin-containing organelles found in melanocytes and melanophores.
A basic helix-loop-helix leucine zipper transcription factor that regulates the CELL DIFFERENTIATION and development of a variety of cell types including MELANOCYTES; OSTEOCLASTS; and RETINAL PIGMENT EPITHELIUM. Mutations in MITF protein have been associated with OSTEOPETROSIS and WAARDENBURG SYNDROME.
Diseases of the nail plate and tissues surrounding it. The concept is limited to primates.
An adrenal disease characterized by the progressive destruction of the ADRENAL CORTEX, resulting in insufficient production of ALDOSTERONE and HYDROCORTISONE. Clinical symptoms include ANOREXIA; NAUSEA; WEIGHT LOSS; MUSCLE WEAKNESS; and HYPERPIGMENTATION of the SKIN due to increase in circulating levels of ACTH precursor hormone which stimulates MELANOCYTES.
The growth of INTESTINAL POLYPS. Growth processes include neoplastic (ADENOMA and CARCINOMA) and non-neoplastic (hyperplastic, mucosal, inflammatory, and other polyps).

Skin pigmentary anomalies and mosaicism for an acentric marker chromosome originating from 3q. (1/182)

We report on a 22 year old man with hyperpigmentation distributed along the lines of Blaschko in whom cytogenetic analysis showed mosaicism for an unusual supernumerary marker chromosome. The patient was of normal intelligence and was not dysmorphic. The marker was present in 30% of his lymphocytes and in 6% of his skin fibroblasts from a dark area, while fibroblasts from a light area showed a normal karyotype, 46,XY. We have identified the origin of the marker using fluorescence in situ hybridisation (FISH) with whole chromosome painting probes and YAC specific clones. The marker was found to consist of duplicated chromosome material from the distal part of chromosome 3q and was interpreted as inv dup(3)(qter-->q27.1::q27.1-->qter). Hence, this marker did not include any known centromeric region and no alpha satellite DNA could be detected at the site of the primary constriction. The patient was therefore tetrasomic for 3q27-q29 in the cells containing the marker chromosome. We postulate that, in our case, pigmentary anomalies may result directly from the gain of specific pigmentation genes localised on chromosome 3q.  (+info)

Effects of renal transplantation on hearing and ocular changes in a monozygotic twin with Alport's syndrome: comparison with other twin on hemodialysis. (2/182)

AIM: To present a unique case of Alport's syndrome in monozygotic twins with two different treatment modalities - renal transplantation and hemodialysis, and to evaluate the effects of therapy on hearing and ophthalmological findings. METHODS: Pure-tone audiogram and ophthalmologic examinations were performed in both twins at the age of 30. At the age of 46, 4 years after renal transplantation in the first twin and after 6 years of hemodialysis in the second twin, both twins underwent control audiometric and ophthalmologic examinations. RESULTS: Control audiometric measurements showed the progression of bilateral sensorineural hearing loss in the high-frequency range (>2,000 Hz) in both twins. The hearing threshold progressed from initial 50 dB in both twins at the time of the diagnosis to 55 dB in the twin on hemodialysis, and 85 dB in the twin with a transplanted kidney. Retinal blurry hyperpigmentations disappeared in the twin with a transplanted kidney. CONCLUSION: In comparison with hemodialysis, renal transplantation in Alport's syndrome may have deleterious effect on hearing, when associated with plasma hyperviscosity and hyperlipidemia, but may lead to regression of retinal hyperpigmentation.  (+info)

NEMO/IKK gamma-deficient mice model incontinentia pigmenti. (3/182)

Disruption of the X-linked gene encoding NF-kappa B essential modulator (NEMO) produces male embryonic lethality, completely blocks NF-kappa B activation by proinflammatory cytokines, and interferes with the generation and/or persistence of lymphocytes. Heterozygous female mice develop patchy skin lesions with massive granulocyte infiltration and hyperproliferation and increased apoptosis of keratinocytes. Diseased animals present severe growth retardation and early mortality. Surviving mice recover almost completely, presumably through clearing the skin of NEMO-deficient keratinocytes. Male lethality and strikingly similar skin lesions in heterozygous females are hallmarks of the human genetic disorder incontinentia pigmenti (IP). Together with the recent discovery that mutations in the human NEMO gene cause IP, our results indicate that we have created a mouse model for that disease.  (+info)

The role of the epidermal endothelin cascade in the hyperpigmentation mechanism of lentigo senilis. (4/182)

Little is known about the mechanism(s) underlying hyperpigmentation in lentigo senilis. We have previously reported that keratinocyte-derived endothelins are intrinsic paracrine mitogens and melanogens for human melanocytes and that they play an essential role in stimulating ultraviolet-B-induced melanogenesis. In this study, we have used immunohistochemistry and reverse transcriptase polymerase chain reaction analysis to clarify the role of the endothelin cascade, including endothelin production, processing by endothelin-converting enzyme, and expression of the endothelin B receptor, in the hyperpigmentary mechanism(s) involved in lentigo senilis. The number of tyrosinase immunopositive melanocytes in lentigo senilis lesional skin was increased 2-fold over the perilesional epidermis. Immunohistochemistry using antibodies to endothelin-1 demonstrated relatively stronger staining in the lesional epidermis than in the perilesional epidermis. Reverse transcriptase polymerase chain reaction analysis concomitantly demonstrated accentuated expression of transcripts for endothelin-1 and for the endothelin B receptor in lentigo senilis lesional skin, which was accompanied by a similar accentuated expression of tyrosinase mRNA compared with the perilesional control. The endothelin-1-inducible cytokine, tumor necrosis factor alpha, was consistently upregulated in the lentigo senilis lesional epidermis as determined at the transcriptional level and by immunostaining, whereas interleukin-1alpha was downregulated. In contrast, endothelin-converting enzyme 1alpha mRNA was not substantially increased in the lesional epidermis. These findings suggest that an accentuation of the epidermal endothelin cascade, especially with respect to expression of endothelin and the endothelin B receptor, plays an important role in the mechanism involved in the hyperpigmentation of lentigo senilis.  (+info)

Short wavelength automated perimetry in age related maculopathy. (5/182)

BACKGROUND/AIMS: Previous studies reported the predictive value of the short wavelength sensitive (SWS) cone mediated sensitivity for visual outcome in age related macular degeneration. In this study SWS sensitivity was measured by commercially available blue on yellow perimetry in patients with non-exudative age related maculopathy (ARM) and compared with the presence of morphological risk factors and the status of the fellow eye. METHODS: In a prospective cross sectional study, 126 patients (57 males, 69 females, mean age 71 (SD 6) years) with ARM (visual acuity >20/50) were tested. Central visual fields (blue on yellow) were obtained with a conventional perimeter. Fundus slides were graded by two independent observers for soft drusen and presence of focal hyperpigmentation. RESULTS: Mean sensitivity and standard deviation of all patients exhibited a significant reduction with age. Patients with soft drusen had significantly lower sensitivity than those without, whereas there were no differences in visual acuity (log MAR). Sensitivity was also reduced in those eyes with fellow eyes having a sight threatening complication of age related macular degeneration (AMD). Eyes with focal hyperpigmentation compared with those without had no loss of sensitivity, but did have a significant decrease in the central part of the field compared with the more eccentric. CONCLUSION: SWS sensitivity loss is associated with common risk factors for progression to AMD. Short wavelength automated perimetry is moderately rapid and readily available. It may serve as a tool in future ARM trials.  (+info)

Refined mapping of Naegeli-Franceschetti- Jadassohn syndrome to a 6 cM interval on chromosome 17q11.2-q21 and investigation of candidate genes. (6/182)

Naegeli-Franceschetti-Jadassohn syndrome and dermatopathia pigmentosa reticularis are autosomal dominant ectodermal dysplasias characterized by the absence of dermatoglyphics, reticulate hyper pigmentation of the skin, hypohidrosis, and heat intolerance. Palmoplantar keratoderma, nail dystrophy, and enamel defects are common in Naegeli-Franceschetti-Jadassohn syndrome, whereas diffuse alopecia is only seen in dermatopathia pigmentosa reticularis. We studied a large Swiss family with Naegeli-Franceschetti-Jadassohn syndrome originally described by Naegeli in 1927 and assessed linkage to chromosome 17q, which was proposed to harbor the Naegeli-Franceschetti-Jadassohn syndrome gene. Our results considerably narrow the Naegeli-Franceschetti-Jadassohn syndrome gene region from 27 cM to 6 cM flanked by D17S933 and D17S934 with a maximum multipoint LOD score of 2.7 at marker locus D17S800. In addition, we studied a small family with dermatopathia pigmentosa reticularis, and our linkage data suggest that dermatopathia pigmentosa reticularis may map to the same chromosomal region. The Naegeli-Franceschetti-Jadassohn syndrome critical interval spans approximately 5.4 Mb and contains a minimum of 45 distinct genes. We scrutinized 13 new prime candidates in addition to five genes previously examined, established the genomic organization of 10 of these genes, and excluded all of them by mutation analysis. Moreover, we identified a cDNA (KRT24) encoding a new keratin protein that bears high similarity to the type I keratins and displays a unique expression profile. No pathogenic mutations were identified in this novel gene either, however. In summary, our results substantially refine the Naegeli-Franceschetti-Jadassohn syndrome region and will aid in identifying a gene that is critical for ontogenesis of multiple ectodermal tissues.  (+info)

Role of dermal melanocytes in cutaneous pigmentation of stasis dermatitis: a histopathological study of 20 cases. (7/182)

Stasis dermatitis is an itchy, scaly, and hyperpigmented condition of the lower leg due to venous insufficiency. Hemosiderin and/or melanin have been considered responsible for the brown pigmentation. However, there are not sufficient histopathologic studies. In this retrospective study the hospital records and biopsy slides of 20 patients were reviewed to determine the pathogenetic mechanisms of brown pigmentation in stasis dermatitis. Fifteen were men (75%) and 5 were women (25%) with a mean age of 46.2+/-8.2 yr (18-76), mean age at onset of 43.4+/-18.0 yr (17-73), and a mean duration of the disease 2.8+/-2.5 yr (0.25-10). All patients had varicose vein and complained of pruritus. On histopathologic evaluation, two cases out of 20 (3 skin biopsy specimens from 25 samples) showed dermal melanocytes containing melanin, and incontinence of melanin pigment was observed in 5 cases, which indicates that melanin pigments from epidermis could contribute to cutaneous pigmentation in stasis dermatitis. However, the existence of dermal melanocytes in two cases cannot be explained because normally the dermis contains no melanocytes. Further studies concerning the role of iron or inflammatory cytokines on the development of dermal melanocytes should be conducted.  (+info)

Aloin, cinnamic acid and sophorcarpidine are potent inhibitors of tyrosinase. (8/182)

OBJECTIVE: To evaluate the effects of aloin, cinnamic acid and 15 other kinds of natural chemicals on the activity of tyrosinase, in order to provide lightening agents in the treatment of hyperpigmentation disorders and cosmetic additives. METHODS: Tyrosinase activity was estimated by measuring the oxidation rate of L-dopa. Inhibition of the enzyme was deduced according to the Lineweaver-Burk plots compared to the control. RESULTS: Cadabine, paeonal, farrerol, evodin, cinnamic acid, aloin and sophorcarpidine had different levels of inhibition of tyrosinase. The inhibitory rates of cinnamic acid (2 mmol/L, 0.5 mmol/L), aloin (2 mmol/L) and the rest were significantly higher than that of hydroquinone (0.5 mmol/L) (P < 0.05). CONCLUSIONS: Tyrosinase activity can be greatly inhibited by cinnamic acid, aloin and sophorcarpidine, of which sophorcarpidine functions as an uncompetitive inhibitor, compared to aloin and cinnamic acid, which are mixed-type inhibitors.  (+info)

Hyperpigmentation is a medical term that refers to the darkening of skin areas due to an increase in melanin, the pigment that provides color to our skin. This condition can affect people of all races and ethnicities, but it's more noticeable in those with lighter skin tones.

Hyperpigmentation can be caused by various factors, including excessive sun exposure, hormonal changes (such as during pregnancy), inflammation, certain medications, and underlying medical conditions like Addison's disease or hemochromatosis. It can also result from skin injuries, such as cuts, burns, or acne, which leave dark spots known as post-inflammatory hyperpigmentation.

There are several types of hyperpigmentation, including:

1. Melasma: This is a common form of hyperpigmentation that typically appears as symmetrical, blotchy patches on the face, particularly the forehead, cheeks, and upper lip. It's often triggered by hormonal changes, such as those experienced during pregnancy or while taking birth control pills.
2. Solar lentigos (age spots or liver spots): These are small, darkened areas of skin that appear due to prolonged sun exposure over time. They typically occur on the face, hands, arms, and decolletage.
3. Post-inflammatory hyperpigmentation: This type of hyperpigmentation occurs when an injury or inflammation heals, leaving behind a darkened area of skin. It's more common in people with darker skin tones.

Treatment for hyperpigmentation depends on the underlying cause and may include topical creams, chemical peels, laser therapy, or microdermabrasion. Preventing further sun damage is crucial to managing hyperpigmentation, so wearing sunscreen with a high SPF and protective clothing is recommended.

Melanosis is a general term that refers to an increased deposit of melanin, the pigment responsible for coloring our skin, in the skin or other organs. It can occur in response to various factors such as sun exposure, aging, or certain medical conditions. There are several types of melanosis, including:

1. Epidermal melanosis: This type of melanosis is characterized by an increase in melanin within the epidermis, the outermost layer of the skin. It can result from sun exposure, hormonal changes, or inflammation.
2. Dermal melanosis: In this type of melanosis, there is an accumulation of melanin within the dermis, the middle layer of the skin. It can be caused by various conditions such as nevus of Ota, nevus of Ito, or melanoma metastasis.
3. Mucosal melanosis: This type of melanosis involves an increase in melanin within the mucous membranes, such as those lining the mouth, nose, and genitals. It can be a sign of systemic disorders like Addison's disease or Peutz-Jeghers syndrome.
4. Lentigo simplex: Also known as simple lentigines, these are small, benign spots that appear on sun-exposed skin. They result from an increase in melanocytes, the cells responsible for producing melanin.
5. Labial melanotic macule: This is a pigmented lesion found on the lips, typically the lower lip. It is more common in darker-skinned individuals and is usually benign but should be monitored for changes that may indicate malignancy.
6. Ocular melanosis: An increase in melanin within the eye can lead to various conditions such as ocular melanocytosis, oculodermal melanocytosis, or choroidal melanoma.

It is important to note that while some forms of melanosis are benign and harmless, others may indicate an underlying medical condition or even malignancy. Therefore, any new or changing pigmented lesions should be evaluated by a healthcare professional.

Skin pigmentation is the coloration of the skin that is primarily determined by two types of melanin pigments, eumelanin and pheomelanin. These pigments are produced by melanocytes, which are specialized cells located in the epidermis. Eumelanin is responsible for brown or black coloration, while pheomelanin produces a red or yellow hue.

The amount and distribution of melanin in the skin can vary depending on genetic factors, age, sun exposure, and various other influences. Increased production of melanin in response to UV radiation from the sun helps protect the skin from damage, leading to darkening or tanning of the skin. However, excessive sun exposure can also cause irregular pigmentation, such as sunspots or freckles.

Abnormalities in skin pigmentation can result from various medical conditions, including albinism (lack of melanin production), vitiligo (loss of melanocytes leading to white patches), and melasma (excessive pigmentation often caused by hormonal changes). These conditions may require medical treatment to manage or improve the pigmentation issues.

Pigmentation disorders are conditions that affect the production or distribution of melanin, the pigment responsible for the color of skin, hair, and eyes. These disorders can cause changes in the color of the skin, resulting in areas that are darker (hyperpigmentation) or lighter (hypopigmentation) than normal. Examples of pigmentation disorders include melasma, age spots, albinism, and vitiligo. The causes, symptoms, and treatments for these conditions can vary widely, so it is important to consult a healthcare provider for an accurate diagnosis and treatment plan.

A lentigo is a small, sharply defined, pigmented macule (flat spot) on the skin. It's usually tan, brown, or black and can appear on various parts of the body, particularly where the skin has been exposed to the sun. Lentigos are typically harmless and don't require treatment unless they're uncomfortable or for cosmetic reasons. However, some types of lentigines, such as lentigo maligna, can progress into melanoma, a type of skin cancer, so regular self-examinations and professional skin checks are important.

It is essential to differentiate between simple lentigos and lentigo maligna, which is a precancerous lesion. Lentigo maligna tends to occur in older individuals, often on the face, and can appear as a large, irregularly shaped, and darkly pigmented patch. A dermatologist should evaluate any suspicious or changing skin spots for proper diagnosis and treatment.

Melanin is a pigment that determines the color of skin, hair, and eyes in humans and animals. It is produced by melanocytes, which are specialized cells found in the epidermis (the outer layer of the skin) and the choroid (the vascular coat of the eye). There are two main types of melanin: eumelanin and pheomelanin. Eumelanin is a black or brown pigment, while pheomelanin is a red or yellow pigment. The amount and type of melanin produced by an individual can affect their skin and hair color, as well as their susceptibility to certain diseases, such as skin cancer.

Facial dermatoses refer to various skin conditions that affect the face. These can include a wide range of disorders, such as:

1. Acne vulgaris: A common skin condition characterized by the formation of comedones (blackheads and whiteheads) and inflammatory papules, pustules, and nodules. It primarily affects the face, neck, chest, and back.
2. Rosacea: A chronic skin condition that causes redness, flushing, and visible blood vessels on the face, along with bumps or pimples and sometimes eye irritation.
3. Seborrheic dermatitis: A common inflammatory skin disorder that causes a red, itchy, and flaky rash, often on the scalp, face, and eyebrows. It can also affect other oily areas of the body, like the sides of the nose and behind the ears.
4. Atopic dermatitis (eczema): A chronic inflammatory skin condition that causes red, itchy, and scaly patches on the skin. While it can occur anywhere on the body, it frequently affects the face, especially in infants and young children.
5. Psoriasis: An autoimmune disorder that results in thick, scaly, silvery, or red patches on the skin. It can affect any part of the body, including the face.
6. Contact dermatitis: A skin reaction caused by direct contact with an allergen or irritant, resulting in redness, itching, and inflammation. The face can be affected when allergens or irritants come into contact with the skin through cosmetics, skincare products, or other substances.
7. Lupus erythematosus: An autoimmune disorder that can cause a butterfly-shaped rash on the cheeks and nose, along with other symptoms like joint pain, fatigue, and photosensitivity.
8. Perioral dermatitis: A inflammatory skin condition that causes redness, small bumps, and dryness around the mouth, often mistaken for acne. It can also affect the skin around the nose and eyes.
9. Vitiligo: An autoimmune disorder that results in the loss of pigmentation in patches of skin, which can occur on the face and other parts of the body.
10. Tinea faciei: A fungal infection that affects the facial skin, causing red, scaly, or itchy patches. It is also known as ringworm of the face.

These are just a few examples of skin conditions that can affect the face. If you experience any unusual symptoms or changes in your skin, it's essential to consult a dermatologist for proper diagnosis and treatment.

Café-au-lait spots are light to dark brown, flat patches on the skin that are benign and usually harmless. The term "café-au-lait" means "coffee with milk," which describes the color of these spots. They can vary in size from a few millimeters to several centimeters in diameter and can appear anywhere on the body, although they are most commonly found on the trunk and buttocks.

While café-au-lait spots are common and can occur in up to 20% of the general population, having multiple (more than six) such spots, especially if they are large or present at birth, may be a sign of an underlying medical condition, such as neurofibromatosis type 1 (NF1), a genetic disorder that affects the growth and development of nerve tissue.

Therefore, it is essential to monitor café-au-lait spots and report any changes or concerns to a healthcare provider.

Bleaching agents are substances that are used to remove color or whiten a variety of materials, including teeth, hair, and fabrics. In the medical field, bleaching agents are often used in dermatology to lighten or eliminate unwanted pigmentation in the skin, such as age spots, sun damage, or melasma.

The most common type of bleaching agent used in dermatology is hydroquinone, which works by inhibiting the production of melanin, the pigment that gives skin its color. Other bleaching agents include retinoic acid, corticosteroids, and kojic acid.

It's important to note that while bleaching agents can be effective in reducing the appearance of unwanted pigmentation, they can also cause side effects such as skin irritation, redness, and dryness. Therefore, it's essential to follow the instructions carefully and consult with a healthcare professional before using any bleaching agent.

Tyrosinase, also known as monophenol monooxygenase, is an enzyme (EC 1.14.18.1) that catalyzes the ortho-hydroxylation of monophenols (like tyrosine) to o-diphenols (like L-DOPA) and the oxidation of o-diphenols to o-quinones. This enzyme plays a crucial role in melanin synthesis, which is responsible for the color of skin, hair, and eyes in humans and animals. Tyrosinase is found in various organisms, including plants, fungi, and animals. In humans, tyrosinase is primarily located in melanocytes, the cells that produce melanin. The enzyme's activity is regulated by several factors, such as pH, temperature, and metal ions like copper, which are essential for its catalytic function.

Melanocytes are specialized cells that produce, store, and transport melanin, the pigment responsible for coloring of the skin, hair, and eyes. They are located in the bottom layer of the epidermis (the outermost layer of the skin) and can also be found in the inner ear and the eye's retina. Melanocytes contain organelles called melanosomes, which produce and store melanin.

Melanin comes in two types: eumelanin (black or brown) and pheomelanin (red or yellow). The amount and type of melanin produced by melanocytes determine the color of a person's skin, hair, and eyes. Exposure to UV radiation from sunlight increases melanin production as a protective response, leading to skin tanning.

Melanocyte dysfunction or abnormalities can lead to various medical conditions, such as albinism (lack of melanin production), melasma (excessive pigmentation), and melanoma (cancerous growth of melanocytes).

Hypopigmentation is a medical term that refers to a condition where there is a decrease in the amount of pigment (melanin) in the skin, resulting in lighter patches or spots on the skin. This can occur due to various reasons such as skin injuries, certain skin disorders like vitiligo, fungal infections, burns, or as a side effect of some medical treatments like chemotherapy or radiation therapy. It is different from albinism, which is a genetic condition where the body is unable to produce melanin at all.

Erythema is a term used in medicine to describe redness of the skin, which occurs as a result of increased blood flow in the superficial capillaries. This redness can be caused by various factors such as inflammation, infection, trauma, or exposure to heat, cold, or ultraviolet radiation. In some cases, erythema may also be accompanied by other symptoms such as swelling, warmth, pain, or itching. It is a common finding in many medical conditions and can vary in severity from mild to severe.

Phototoxic dermatitis is a skin reaction that occurs when certain chemicals (known as photosensitizers) in a substance come into contact with the skin and then are exposed to sunlight or artificial UV light. This results in an exaggerated sunburn-like reaction, characterized by redness, swelling, itching, and sometimes blistering of the skin. The reaction usually occurs within a few hours to a couple of days after exposure to the offending agent and light. Common causes include certain medications, essential oils, fragrances, and plants like limes, celery, and parsley. Once the irritant is no longer in contact with the skin and sun exposure is avoided, the symptoms typically resolve within a week or two. Prevention includes avoiding the offending agent and protecting the skin from sunlight through the use of clothing, hats, and broad-spectrum sunscreens.

A Nevus of Ota, also known as an oculodermal melanocytosis, is a benign birthmark characterized by the presence of darkly pigmented (melanin-containing) cells called melanocytes in the skin and mucous membranes around the eye. These pigmented cells can also extend to the sclera (the white part of the eye), dura mater (the outer covering of the brain), and leptomeninges (the middle layer of the meninges, which cover the brain and spinal cord).

The Nevus of Ota typically presents as a unilateral (occurring on one side) bluish-gray or brown patch that follows the distribution of the ophthalmic and maxillary divisions of the trigeminal nerve. It usually affects the eye, forehead, temple, and cheek, but it can also involve other areas of the face, scalp, and neck.

While Nevi of Ota are generally harmless, they may be associated with an increased risk of developing melanoma (a type of skin cancer) in the affected area. Therefore, regular monitoring and evaluation by a healthcare professional is recommended.

Tinea versicolor is a superficial fungal infection of the skin, caused by the pathogen Malassezia furfur (previously known as Pityrosporum ovale). It is characterized by the appearance of multiple round or oval patches that are hypopigmented (lighter than the surrounding skin) or hyperpigmented (darker than the surrounding skin), scaly, and can be pruritic (itchy). The lesions typically appear on the trunk and proximal extremities, often in a symmetrical pattern. Tinea versicolor is more common in warm, humid climates and in individuals with oily skin or weakened immune systems. It is usually diagnosed based on the clinical presentation and can be confirmed by microscopic examination of skin scrapings or fungal cultures. Treatment typically involves topical antifungal medications, such as clotrimazole, miconazole, or selenium sulfide, but oral medication may be necessary for severe or widespread infections.

Acne vulgaris is a common skin condition characterized by the formation of various types of blemishes on the skin, such as blackheads, whiteheads, papules, pustules, and cysts or nodules. These lesions typically appear on areas of the body that have a high concentration of sebaceous glands, including the face, neck, chest, back, and shoulders.

Acne vulgaris occurs when hair follicles become clogged with dead skin cells and excess oil (sebum) produced by the sebaceous glands. This blockage provides an ideal environment for bacteria, particularly Propionibacterium acnes, to multiply, leading to inflammation and infection. The severity of acne vulgaris can range from mild with only a few scattered comedones (blackheads or whiteheads) to severe cystic acne, which can cause significant scarring and emotional distress.

The exact causes of acne vulgaris are not fully understood, but several factors contribute to its development, including:

1. Hormonal changes during puberty, menstruation, pregnancy, or due to conditions like polycystic ovary syndrome (PCOS)
2. Genetic predisposition
3. Use of certain medications, such as corticosteroids and lithium
4. Excessive production of sebum due to overactive sebaceous glands
5. Accumulation of dead skin cells that clog pores
6. Bacterial infection (particularly Propionibacterium acnes)
7. Inflammation caused by the body's immune response to bacterial infection and clogged pores

Treatment for acne vulgaris depends on its severity and can include over-the-counter or prescription topical treatments, oral medications, chemical peels, light therapies, or even hormonal therapies in some cases. It is essential to seek professional medical advice from a dermatologist or healthcare provider to determine the most appropriate treatment plan for individual needs.

Acanthosis nigricans is a medical condition characterized by the darkening and thickening of the skin in certain areas of the body. These areas typically include the back of the neck, armpits, groin, and skin folds. The skin becomes velvety to touch, and may have a "dirty" appearance.

The condition is often associated with insulin resistance, which can be a sign of type 2 diabetes or prediabetes. It can also be linked to obesity, hormonal imbalances, certain medications, and some rare genetic syndromes.

In addition to the changes in skin color and texture, people with acanthosis nigricans may also experience itching, odor, or discomfort in the affected areas. Treatment typically involves addressing the underlying cause of the condition, such as managing diabetes or losing weight. Topical treatments may also be used to improve the appearance of the skin.

Skin diseases, also known as dermatological conditions, refer to any medical condition that affects the skin, which is the largest organ of the human body. These diseases can affect the skin's function, appearance, or overall health. They can be caused by various factors, including genetics, infections, allergies, environmental factors, and aging.

Skin diseases can present in many different forms, such as rashes, blisters, sores, discolorations, growths, or changes in texture. Some common examples of skin diseases include acne, eczema, psoriasis, dermatitis, fungal infections, viral infections, bacterial infections, and skin cancer.

The symptoms and severity of skin diseases can vary widely depending on the specific condition and individual factors. Some skin diseases are mild and can be treated with over-the-counter medications or topical creams, while others may require more intensive treatments such as prescription medications, light therapy, or even surgery.

It is important to seek medical attention if you experience any unusual or persistent changes in your skin, as some skin diseases can be serious or indicative of other underlying health conditions. A dermatologist is a medical doctor who specializes in the diagnosis and treatment of skin diseases.

Flatfishes are a group of marine fish characterized by having both eyes on one side of their head, which is flattened laterally. This gives them a distinctive asymmetrical appearance. They belong to the order Pleuronectiformes and include various species such as halibut, flounder, sole, and plaice. Flatfishes start their life with eyes on both sides of their head, but during development, one eye migrates to the other side of the head, a process known as metamorphosis. They are bottom-dwelling predators that rely on their excellent camouflage abilities to ambush prey.

Photosensitivity disorders refer to conditions that cause an abnormal reaction to sunlight or artificial light. This reaction can take the form of various skin changes, such as rashes, inflammation, or pigmentation, and in some cases, it can also lead to systemic symptoms like fatigue, fever, or joint pain.

The two main types of photosensitivity disorders are:

1. Phototoxic reactions: These occur when a substance (such as certain medications, chemicals, or plants) absorbs light energy and transfers it to skin cells, causing damage and inflammation. The reaction typically appears within 24 hours of exposure to the light source and can resemble a sunburn.

2. Photoallergic reactions: These occur when the immune system responds to the combination of light and a particular substance, leading to an allergic response. The reaction may not appear until several days after initial exposure and can cause redness, itching, and blistering.

It is important for individuals with photosensitivity disorders to avoid excessive sun exposure, wear protective clothing, and use broad-spectrum sunscreens with a high SPF rating to minimize the risk of phototoxic or photoallergic reactions.

Hydroquinones are a type of chemical compound that belong to the group of phenols. In a medical context, hydroquinones are often used as topical agents for skin lightening and the treatment of hyperpigmentation disorders such as melasma, age spots, and freckles. They work by inhibiting the enzyme tyrosinase, which is necessary for the production of melanin, the pigment that gives skin its color.

It's important to note that hydroquinones can have side effects, including skin irritation, redness, and contact dermatitis. Prolonged use or high concentrations may also cause ochronosis, a condition characterized by blue-black discoloration of the skin. Therefore, they should be used under the supervision of a healthcare provider and for limited periods of time.

A "drug eruption" is a general term used to describe an adverse skin reaction that occurs as a result of taking a medication. These reactions can vary in severity and appearance, and may include symptoms such as rash, hives, itching, redness, blistering, or peeling of the skin. In some cases, drug eruptions can also cause systemic symptoms such as fever, fatigue, or joint pain.

The exact mechanism by which drugs cause eruptions is not fully understood, but it is thought to involve an abnormal immune response to the medication. There are many different types of drug eruptions, including morphilliform rashes, urticaria (hives), fixed drug eruptions, and Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), which is a severe and potentially life-threatening reaction.

If you suspect that you are experiencing a drug eruption, it is important to seek medical attention promptly. Your healthcare provider can help determine the cause of the reaction and recommend appropriate treatment. In some cases, it may be necessary to discontinue the medication causing the reaction and switch to an alternative therapy.

Dermatologic agents are medications, chemicals, or other substances that are applied to the skin (dermis) for therapeutic or cosmetic purposes. They can be used to treat various skin conditions such as acne, eczema, psoriasis, fungal infections, and wounds. Dermatologic agents include topical corticosteroids, antibiotics, antifungals, retinoids, benzoyl peroxide, salicylic acid, and many others. They can come in various forms such as creams, ointments, gels, lotions, solutions, and patches. It is important to follow the instructions for use carefully to ensure safety and effectiveness.

Agaricales is an order of fungi that includes mushrooms, toadstools, and other gilled fungi. These fungi are characterized by their distinctive fruiting bodies, which have a cap (pileus) and stem (stipe), and gills (lamellae) on the underside of the cap where the spores are produced. Agaricales contains many well-known and economically important genera, such as Agaricus (which includes the common button mushroom), Amanita (which includes the deadly "death cap" mushroom), and Coprinus (which includes the inky cap mushrooms). The order was established by the Swedish mycologist Elias Magnus Fries in 1821.

Neurofibromatoses are a group of genetic disorders that primarily affect the nervous system. The term "neurofibromatosis" is often used to refer to two specific conditions: neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2). These conditions are characterized by the growth of tumors on the nerves, called neurofibromas.

Neurofibromatosis type 1 (NF1): This is the most common form of neurofibromatosis, affecting about 1 in every 3,000 people worldwide. NF1 is caused by mutations in the NF1 gene and is characterized by the development of benign tumors on the nerves called neurofibromas. These tumors can develop anywhere on the body, including the skin, spinal cord, and brain. Other common features of NF1 include:

* Freckles in the underarms and groin area
* Lisch nodules (small, noncancerous growths) on the iris of the eye
* Bone abnormalities, such as scoliosis or bowing of the legs
* Learning disabilities or cognitive impairment

Neurofibromatosis type 2 (NF2): This form of neurofibromatosis is much rarer than NF1, affecting about 1 in every 30,000 people worldwide. NF2 is caused by mutations in the NF2 gene and is characterized by the development of benign tumors on the nerves that transmit sound from the inner ear to the brain (acoustic neuromas). These tumors can cause hearing loss, ringing in the ears, and balance problems. Other common features of NF2 include:

* Multiple schwannomas (tumors that develop on the protective covering of the nerves)
* Meningiomas (tumors that develop in the membranes surrounding the brain and spinal cord)
* Skin tumors called neurofibromas, although these are less common than in NF1

It is important to note that while neurofibromatoses can cause a range of symptoms and complications, most people with these conditions have a normal lifespan. With proper medical care and monitoring, it is possible to manage the symptoms and reduce the risk of complications.

Melanosomes are membrane-bound organelles found in melanocytes, the pigment-producing cells in the skin, hair, and eyes. They contain the pigment melanin, which is responsible for giving color to these tissues. Melanosomes are produced in the melanocyte and then transferred to surrounding keratinocytes in the epidermis via a process called cytocrinesis. There are four stages of melanosome development: stage I (immature), stage II (developing), stage III (mature), and stage IV (degrading). The amount and type of melanin in the melanosomes determine the color of an individual's skin, hair, and eyes. Mutations in genes involved in melanosome biogenesis or function can lead to various pigmentation disorders, such as albinism.

The Microphthalmia-Associated Transcription Factor (MITF) is a protein that functions as a transcription factor, which means it regulates the expression of specific genes. It belongs to the basic helix-loop-helix leucine zipper (bHLH-Zip) family of transcription factors and plays crucial roles in various biological processes such as cell growth, differentiation, and survival.

MITF is particularly well-known for its role in the development and function of melanocytes, the pigment-producing cells found in the skin, eyes, and inner ear. It regulates the expression of genes involved in melanin synthesis and thus influences hair and skin color. Mutations in the MITF gene have been associated with certain eye disorders, including microphthalmia (small or underdeveloped eyes), iris coloboma (a gap or hole in the iris), and Waardenburg syndrome type 2A (an inherited disorder characterized by hearing loss and pigmentation abnormalities).

In addition to its role in melanocytes, MITF also plays a part in the development and function of other cell types, including osteoclasts (cells involved in bone resorption), mast cells (immune cells involved in allergic reactions), and retinal pigment epithelial cells (a type of cell found in the eye).

Nail diseases, also known as onychopathies, refer to a group of medical conditions that affect the nail unit, which includes the nail plate, nail bed, lunula, and surrounding skin (nail fold). These diseases can be caused by various factors such as fungal infections, bacterial infections, viral infections, systemic diseases, trauma, and neoplasms.

Some common examples of nail diseases include:

1. Onychomycosis - a fungal infection that affects the nail plate and bed, causing discoloration, thickening, and crumbling of the nail.
2. Paronychia - an infection or inflammation of the nail fold, caused by bacteria or fungi, resulting in redness, swelling, and pain.
3. Ingrown toenails - a condition where the nail plate grows into the surrounding skin, causing pain, redness, and infection.
4. Onycholysis - a separation of the nail plate from the nail bed, often caused by trauma or underlying medical conditions.
5. Psoriasis - a systemic disease that can affect the nails, causing pitting, ridging, discoloration, and onycholysis.
6. Lichen planus - an inflammatory condition that can affect the skin and nails, causing nail thinning, ridging, and loss.
7. Melanonychia - a darkening of the nail plate due to pigmentation, which can be benign or malignant.
8. Brittle nails - a condition characterized by weak, thin, and fragile nails that easily break or split.
9. Subungual hematoma - a collection of blood under the nail plate, often caused by trauma, resulting in discoloration and pain.
10. Tumors - abnormal growths that can develop in or around the nail unit, ranging from benign to malignant.

Accurate diagnosis and treatment of nail diseases require a thorough examination and sometimes laboratory tests, such as fungal cultures or skin biopsies. Treatment options vary depending on the underlying cause and may include topical or oral medications, surgical intervention, or lifestyle modifications.

Addison disease, also known as primary adrenal insufficiency or hypocortisolism, is a rare endocrine disorder characterized by the dysfunction and underproduction of hormones produced by the adrenal glands, specifically cortisol and aldosterone. The adrenal glands are located on top of the kidneys and play a crucial role in regulating various bodily functions such as metabolism, blood pressure, stress response, and immune system function.

The primary cause of Addison disease is the destruction of more than 90% of the adrenal cortex, which is the outer layer of the adrenal glands responsible for hormone production. This damage can be due to an autoimmune disorder where the body's immune system mistakenly attacks and destroys the adrenal gland tissue, infections such as tuberculosis or HIV, cancer, genetic disorders, or certain medications.

The symptoms of Addison disease often develop gradually and may include fatigue, weakness, weight loss, decreased appetite, low blood pressure, darkening of the skin, and mood changes. In some cases, an acute crisis known as acute adrenal insufficiency or Addisonian crisis can occur, which is a medical emergency characterized by sudden and severe symptoms such as extreme weakness, confusion, dehydration, vomiting, diarrhea, low blood sugar, and coma.

Diagnosis of Addison disease typically involves blood tests to measure hormone levels, imaging studies such as CT scans or MRIs to assess the adrenal glands' size and structure, and stimulation tests to evaluate the adrenal glands' function. Treatment usually involves replacing the missing hormones with medications such as hydrocortisone, fludrocortisone, and sometimes mineralocorticoids. With proper treatment and management, individuals with Addison disease can lead normal and productive lives.

Intestinal polyposis is a condition characterized by the presence of multiple polyps in the inner lining (mucosa) of the intestines. These polyps are abnormal growths that protrude from the intestinal wall and can vary in size, number, and type. Some common types of polyps include adenomatous, hyperplastic, and inflammatory polyps.

Intestinal polyposis can occur throughout the gastrointestinal tract, including the stomach, small intestine, and large intestine (colon). The condition can be inherited or acquired, and it is often associated with various genetic syndromes such as familial adenomatous polyposis (FAP), Peutz-Jeghers syndrome, juvenile polyposis syndrome, and Lynch syndrome.

Depending on the type, size, and number of polyps, intestinal polyposis can increase the risk of developing colorectal cancer and other gastrointestinal malignancies. Regular surveillance, monitoring, and removal of polyps are essential for managing this condition and preventing complications.

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