Extensive involvement of the gastrointestinal tract by a de novo presentation of the monoblastic type of myeloid sarcoma: a case report of a rare entity that is often misdiagnosed.

We present the first known case of the monoblastic type of myeloid sarcoma (also known as extramedullary myeloid tumor, chloroma, and granulocytic sarcoma) with diffuse involvement of the gastrointestinal tract. The patient originally presented with diarrhea and crampy abdominal discomfort. Endoscopically, the disease showed a diffuse inflammatory process mimicking a number of benign conditions, such as inflammatory bowel disease and autoimmune enteropathy. Sequential biopsies of the upper and lower gastrointestinal tract showed a diffuse infiltrate of increasingly atypical cells. The disease progressed to systemic involvement, including widespread lymphadenopathy, splenomegaly, and pulmonary deposits; the patient died 13 months after the development of initial symptoms. The immunohistochemical and histologic profiles of this case are diagnostic of the monoblastic type of myeloid sarcoma.