Criteria:
(1) typical skin lesions for
(1a) urticaria pigmentosa (UP) or maculopapular cutaneous mastocytosis (MPCM)
(1b) diffuse cutaneous mastocytosis (DCM)
(1c) solitary mastocytoma
(2) histologic examination of a skin biopsy shows an infiltrate of mast cells with a multi-focal or diffuse pattern
Features of urticaria pigmentosa:
(1) small, yellowish-tan to reddish-brown macules or slightly raised papules
(2) Darier's sign is present (mild trauma causes urtication and erythema about the lesions)
(3) pruritis may be present and can be exacerbated by certain triggers (change in environmental temperature, exposure to drugs or alcohol, eating hot or spicy food, skin friction)
Features of diffuse cutaneous mastocytosis:
(1) diffuse involvement of the skin without discrete lesions
(2) skin color ranges from normal to yellow-brown (in Caucasians)
(3) usually affects children < 3 years of age
