A name applied to several itchy skin eruptions of unknown cause. The characteristic course is the formation of a dome-shaped papule with a small transient vesicle on top, followed by crusting over or lichenification. (From Dorland, 27th ed)

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.

An intense itching sensation that produces the urge to rub or scratch the skin to obtain relief.

'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.