1935 An Unusual Cause of Post-Polypectomy Bleeding

Abstract

INTRODUCTION: Myeloid sarcoma is a rare tumor characterized by a tissue mass of myeloid progenitor cells occurring outside of the bone marrow. Myeloid sarcoma can occur de novo or overlap with acute myeloid leukemia (AML). As with AML, myeloid sarcoma may also present as a blast transformation of myelodysplastic syndrome or neoplasm. CASE DESCRIPTION/METHODS: A 65-year-old male was transferred to our hospital for hematochezia after a cecal polypectomy. Two days prior to transfer, the patient underwent screening colonoscopy for colorectal cancer at an outside hospital. During the procedure, a large carpeted, sessile polyp was seen overlying the cecal fold. Endoscopic removal was attempted but was unsuccessful given the polyp’s location and size. Pathology from the partially removed polyp revealed a tubulovillous adenoma. His hemoglobin was 6.5 g/dL (13.0–17.0 g/dL) and white blood cell count was 70 M/μL (4.20–5.60 M/μL). Following blood transfusions and hemodynamic stabilization, repeat colonoscopy and bone marrow biopsy were performed. The polypectomy site revealed flat, polypoid ulcerated and friable tissue with multiple areas of bleeding and clot (Figure 1). Despite hemostatic clip placement and thermal therapy to treat areas of active oozing, the lesion continued to bleed. The surgical team was activated given known residual adenomatous tissue and the patient underwent a successful right hemicolectomy. Pathology of the surgical specimen showed a tubulovillous adenoma with focal high-grade dysplasia and central ulceration with fibrinous exudate and submucosal hemorrhage. In addition, there were immature myeloid cells infiltrating the submucosa underneath this polyp. Furthermore, sheets of myeloblasts, positive for CD34 and CD117, within the submucosa also formed a separate ulcerated, plaque-like, 1.0 cm mass distal to the polyp (Figure 2). Bone marrow biopsy showed a 70% cellular marrow with nearly 20% myeloblasts. The patient had both a tubulovillous adenoma with an infiltrating adjacent myeloid sarcoma. DISCUSSION: While myeloid sarcoma can affect any organ, they most commonly infiltrate the skin or gums. Colonic involvement is extremely rare. Treatment for myeloid sarcomas is identical to that of AML, even if there no evidence of bone marrow involvement.