S2991 Gastric Myeloid Sarcoma as a Presentation of Relapsed Acute Myelomonocytic Leukemia - A Case Report

Abstract

INTRODUCTION: Myeloid sarcoma is an extramedullary proliferation of myeloid blasts that may be associated with a concurrent myeloid neoplasm involving the bone marrow, but such an association is not required. In some cases, myeloid sarcoma may herald a relapse in a patient with previously treated disease. In others, it may be the first indication of acute leukemia. CASE DESCRIPTION/METHODS: A 48-year-old male presented with nausea, vomiting and epigastric pain. Physical examination showed tachycardia, and epigastric tenderness. Nine months earlier he was diagnosed with acute myelomonocytic leukemia; cytogenetics showed 47,XY,+8,t(9;11)(p21.3;q23.3). At that time, he was treated with standard induction therapy with the 7 + 3 regimen with Cytarabine and Daunorubicin followed by 3 cycles of High-Dose Cytarabine (HiDAC). Lab results showed pancytopenia including Leukopenia with 19% blasts. Peripheral blood flow cytometry showed 18% monoblasts. CT chest and abdomen revealed diffuse lobular thickening of the gastric wall, segmental thickening of the small bowel loops, and pancreatic, paraspinal, and infiltrative right ventricular wall masses. Upper GI endoscopy showed thickened gastric folds with a nodular mucosa. Gastric mucosal resection was performed, and biopsy showed abnormal blasts infiltrating through the mucosal glands, consistent with myeloid sarcoma. A bone marrow biopsy was consistent with relapsed AML. Urgent therapy was instituted however the patient suffered a cardiac arrest and resuscitation was unsuccessful. DISCUSSION: Myeloid sarcoma (aka granulocytic sarcoma, myeloblastoma, or chloroma) may present simultaneously with, or precede bone marrow disease and may be seen in relapse or as progression of a prior myeloproliferative neoplasm. The most common sites of isolated myeloid sarcoma are the skin, followed by mucous membranes, orbits, central nervous system, and other internal organs. Myeloid sarcoma is more common in pediatric AML, although the true incidence in adults is unknown. In adults, roughly one third of myeloid sarcomas present with concurrent myeloid disease, and one third have a history of a prior myeloid neoplasm. The presence of a myeloid sarcoma is diagnostic of AML, regardless of the bone marrow status, or blast count. The diagnosis of myeloid sarcoma should be restricted to tumors that form space-occupying lesions. The approach to treatment of patients with myeloid sarcoma without evidence of AML on bone marrow biopsy is similar to that for patients with overt AML.Figure 1.: CT Abdomen showing lobular thickening of the gastric wall.Figure 2.: Upper GI endoscopy showing thickened gastric folds with nodular mucosa in the gastric body. Findings are concerning of infiltrative malignancy.Figure 3.: High power (10x) view of Hematoxylin and Eosin stain of gastric body biopsy showing abnormal monoblasts infiltrating through the mucosal glands, consistent with myeloid sarcoma.