a) papular urticaria _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯

b) follicular (papular) eczema _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯

c) urticaria pigmentosum _ _ _ _ _ _ _ _ _ _ Correct ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯

d) incontinentia pigmenti _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯

e) multiple leiomyomas _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯

Answer and Commentary _ _ _ _ _ _ _ _ _ _ Urticaria pigmentosum is an important disease of childhood. In the thumb-sized pigmented macules there is a dramatic increase in the number of mast cells. When rubbed the mast cells degranulate, releasing histamine and other potent mediators - and the lesion wheals. This form of mastocytosis is generally restricted to the skin and regularly clears at or before puberty. ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯