Histaminuria in Mastocytosis

Mastocytosis, the abnormal proliferation of tissue mast cells, may occur in a cutaneous, systemic, splenic, or leukemic form. Of these, cutaneous mastocytosis is apparently the most prevalent, and in its commonest clinical form, urticaria pigmentosa, it appears as hyperpigmented macules of the trunk which become urticarial with mild trauma. The primary pathologic finding is a mast-cell infiltration of the upper corium. Riley1found that these mast cells contain large amounts of histamine. Increased urinary excretion of histamine by patients with urticaria pigmentosa was first demonstrated by Pernow and Waldenstrom.2 We have evaluated 19 patients with cutaneous mastocytosis, and histaminuria was observed in each case. A number of these patients have a "mastocytosis syndrome" characterized by episodic erythematous flushing, tachycardia and hypotension, headache, upper gastrointestinal distress, diarrhea, and pruritus. These symptoms are known effects of increased amounts of circulating histamine and in our patients were associated with increased urinary