Chronic intractable diarrhea caused by gastrointestinal mastocytosis

As mast cells have been highlighted in the pathogenesis of diarrhea-predominant irritable bowel syndrome, a new term "mastocytic enterocolitis" was suggested by Jakate and colleagues to describe an increase in mucosal mast cells in patients with chronic intractable diarrhea and favorable response to treatment with antihistamines. Although it is not an established disease entity, two cases have been reported in the English medical literature. Here, for the first time in Asia, we report another case of chronic intractable diarrhea caused by gastrointestinal mastocytosis. The patient was a 70-year-old male with chronic intractable diarrhea for 3 months; the cause of the diarrhea remained obscure even after exhaustive evaluation. However, biopsy specimens from the jejunum were found to have increased mast cell infiltration, and the patient was successfully treated with antihistamines.