Urticaria pigmentosa (also known as "Generalized eruption of cutaneous mastocytosis (childhood type)" ) is the most common form of cutaneous mastocytosis. It is a rare disease caused by excessive numbers of mast cells in the skin that produce hives or lesions on the skin when irritated.
Read more about Urticaria Pigmentosa: Signs and Symptoms, Cause, Diagnosis, Treatments, Epidemiology