Nodularity of the small intestine in a child with systemic mastocytosis associated with hyperimmunoglobulin M syndrome.

A 7-year-old boy with hyperimmunoglobulin M syndrome presented with intermittent bloody diarrhea since the age of 6 months. On physical examination he had hepatosplenomegaly, generalized lympadenopathy, and hyperpigmented papular/vesicular rash around the umbilicus. The growth parameters were normal. The skin biopsy wasconsistent withmastocytoma. Endoscopic evaluationrevealednodular smallintestinal mucosa. Themostprominent nodularity wasseen intheduodenum (Fig. 1), and less so in the terminal ileum. The histology revealed acute and chronic inflammation without architectural changes, and a high number of mastocytes, confirming systemic mastocytosis (Fig. 2). Treatment with monthly intravenous gamma globulin, antihistamines, ketotifen, and proton pump inhibitor resulted in almost complete resolution of gastrointestinal symptoms. Mastocytosisischaracterizedbyexcessiveproliferationofmastocytesinseveralorgans,mostfrequentlyskin,bones,lymphnodes,liver,spleen,andthegastrointestinaltract(1).Systemicmastocytosisisrareinchildren(2).Therapyisbasedonsymptomatictreatmentandavoidingtriggersofmastcellmediatorrelease.Long-termprognosisforpediatric-onsetdiseaseisbetterincontrasttoadult-onsetmastocytosis(3).HyperimmunoglobulinMalsocanbeassociatedwithchronicdiarrhea.Both Cryptosporidium and Giardia rarelycausenodularityofthesmallintestine(4);however,noetiologicmicroorganismwasidentifiedonstooltesting.Therefore,giventhe histologic picture a showing high number of mastocytes, we presume that the symptoms and the nodular mucosal changes were caused by systemic mastocytosis.