Long-term treatment of systemic mastocytosis with histamine H2 receptor antagonists.

A patient with systemic mastocytosis, accompanied by gastric hypersecretion and duodenal ulcer, was treated with metiamide followed by daily cimetidine for 44 months. Treatment with cimetidine resulted in healing of the ulcer, without recurrence and marked amelioration of the cutaneous symptoms of mastocytosis. Complete suppression of basal gastric hypersecretion was documented after 33 months of treatment and cimetidine and Vitamin B12 absorption remained normal. Cimetidine reduced the patient's cutaneous response to intradermal histamine without affecting leucocyte histamine release. No cimetidine toxicity was observed. These results indicate that effective long-term control of histamine-induced gastric hypersecretion can be achieved with cimetidine. They suggest that some of the cutaneous symptoms of mastocytosis are mediated via histamine H2 receptors in the skin.