Extramedullary hematopoiesis involving the esophagus in myelofibrosis. In this report, we describe a case of myelofibrosis with myeloid metaplasia; a 53-yr-old man was splenectomized for a massively enlarged spleen in which multiple foci of myeloid metaplasia were histologically demonstrated. The patient was referred to us for endoscopic examination, following the repeated occurrence of melena. Upper gastrointestinal endoscopy revealed two active ulcerative lesions in the bulb, and only a moderate erythema in the lower third of the esophagus, which showed no varices. There was no endoscopic evidence of active or recent bleeding. Subsequent histologic examination of biopsies taken from the esophageal lesion surprisingly revealed the presence of hematopoietic tissue. 