Gastrointestinal multicentric infantile myofibromatosis: characteristic histology on rectal biopsy.

A 10-wk-old girl with growth failure and increasingly severe watery diarrhea underwent rectal biopsy which revealed diffuse mucosal fibrosis. Subsequent histologic study of mediastinal and subcutaneous masses established the diagnosis of multicentric infantile myofibromatosis. The patient died at 16 wk of age with tumor nodules in several visceral and parietal structures. The small and large intestines contained continuous, diffuse and nodular, mucosal and submucosal fibrosis. Twelve previously reported cases of multicentric infantile myofibromatosis involved the gastrointestinal tract; four had prominent gastrointestinal clinical manifestations. In two, diarrhea was prominent. The present case demonstrates the potential value of rectal biopsy in the diagnosis of infantile myofibromatosis with gastrointestinal manifestations.