An Unusual Cause for GI Bleed

Abstract

Purpose: Agnogenic myeloid metaplasia (AMM) is a rare myeloproliferative disorder characterized by bone marrow fibrosis, marked splenomegaly, and extramedullary hematopoeisis (EMH). EMH can occur in almost any organ, but clinically significant involvement of the gastrointestinal (GI) tract is very rare. Methods: A 62-year-old female with AMM with myelofibrosis was transferred to our institution for evaluation of overt gastrointestinal bleeding of obscure origin. She presented with a six-month history of recurrent hematochezia. Her extensive previous workup had included six negative upper endoscopies and three colonoscopies, which were unremarkable except for the presence of blood throughout the colon. Three nuclear medicine bleeding scans had also been performed, two of which showed active bleeding arising from the right lateral hemipelvis. Subsequent angiograms, however, were negative. The patient had received 17 units of PRBC over the two weeks prior to her transfer to our institution. Results: Physical exam revealed a chronically ill patient with marked hepatosplenomegaly. Laboratory data showed a hemoglobin of 7.9 mg/dL and platelet count of 46,000/uL. CT enterography demonstrated an abnormal focal accumulation of intravenous contrast in the wall or lumen of a loop of mid-to-distal ileum, without mass or abnormal wall thickening. Angiography was again negative, and retrograde double balloon enteroscopy was nondiagnostic. Video capsule endoscopy visualized a small, smooth, dome-like protuberance arising from otherwise normal appearing small bowel mucosa at 4 hours and 40 minutes. At the apex of the lesion, there appeared to be a small umbilication, and possibly an adjacent clot. Due to the severity of her bleeding, she underwent exploratory laparotomy with intraoperative enteroscopy. A lesion was palpated in the jejunum, and endoscopically identified as the same lesion seen on capsule study. This was resected, and on gross pathology was described as a 0.7-cm submucosal nodule with mild erythema and umbilication. Histology and immunoperoxidase studies revealed a cluster of erythroid cells, granulocytic and myeloid precursors, and megakaryocytes, consistent with focal EMH. Postoperatively, the patient had no further bleeding. Conclusion: EMH is common in patients with myelofibrosis, affecting organs containing tissue of mesenchymal origin. However, clinically significant GI tract involvement is very rare. GI bleeding from EMH in the esophagus, small bowel, and colon has been described in a small number of case reports. To our knowledge, this is the first case of GI bleeding arising from a single focus of small bowel EMH visualized on video capsule endoscopy.