Shock in an infant with bullous mastocytosis.

A 6-month-old infant had bullous lesions on his posterior neck, upper trunk, and extremities for two months prior to admission for fever and shock. He had an elevated white blood cell count with left shift and normal platelet count, but abnormal coagulation studies. He was treated with intravenous antibiotics, crystalloids, fresh-frozen plasma, and pressor agents. A histamine H2 receptor antagonist was started for guaiac-positive nasogastric tube drainage. The patient recovered after four days of treatment. A skin biopsy confirmed mastocytosis. A week later the child passed grossly bloody stools with blood clots. No source of gastrointestinal bleeding was identified by extensive work-up. Blood histamine level measured one day before gastrointestinal bleeding was 16,400 pg/ml (normal 263 +/- 202 pg/ml). The bleeding resolved spontaneously. The patient was maintained on cimetidine. Results of a subsequent bone scan were normal. Shock or gastrointestinal bleeding associated with unusual skin lesions should alert the pediatrician to the possibility of mastocytosis.