The case which is presented and review of the literature indicate that urticaria pigmentosa may be accompanied by mast cell infiltration of many tissues and viscera. No definite conclusions may be drawn regarding etiology, incidence, or prognosis of this disorder. The evidence indicates that both local and generalized symptoms occur which are principally related to the pathophysiologic changes resulting from mast cell activity, i.e., fibrous tissue proliferation, hyperemia and edema.
In the case reported herein there was no histologic evidence of fibrous tissue increase but it is postulated that the hepatosplenomegaly and the bone changes in roentgenograms may be in part due to such changes. The dermatographism, skin flushing, salivary gland swelling and gastrointestinal symptoms are probably due to the physiologic action of mast cell products, i.e., histamine and serotonin.
The diagnosis of generalized mast cell disease can be made in a patient who presents a chronic maculopapular skin rash, dermatographism, hepatosplenomegaly and mast cell infiltration of the bone marrow. Demonstration of mast cell infiltration in the skin and other tissues is confirmatory but not necessary.
An Electron Microscopic Study of the Degranulation of Mast Cell Granules in Urticaria Pigmentosa*
