Hidradenitis Suppurativa
A non-contagious skin disease

Mastocytosis
A disorder characterized by abnormal accumulations of mast cells in skin (urticaria pigmentosa), and in bone marrow, and internal organs such as the liver, spleen and lymph nodes (systemic mastocytosis).

Scleredema
Scleredema is a skin condition characterized by hardening of the skin with occasional redness. Its cause is unknown.

Sweets syndrome/neutrophilic dermatosis
Also known as acute febrile neutrophilic dermatosis, this syndrome is a hypersensitivity reaction which results in fever and raised painful plaques on the skin.

Urticaria
Itchy welts or wheals which usually appear suddenly as a result of exposure to food, infection, sunlight, water, pressure, and many other causes.

Xeroderma pigmentosum (XP)
Xeroderma pigmentosum is a rare genetic defect in ultraviolet radiation-induced DNA repair mechanisms. Find links to information and resources for the disorder.