INTRODUCTION: Upper GI bleed is not uncommon in routine practice. Myeloid sarcoma (MS) or granulocytic sarcoma is an extramedullary proliferation of blasts of one of the myeloid lineages and commonly involves soft tissue, bone, skin, lymph nodes and the periosteum. MS of the GI tract is extremely uncommon, and involvement of the stomach is even rarer. We present a unique case of MS of the stomach. CASE DESCRIPTION/METHODS: 69 y/o male with PMH of hypertension, diabetes, CAD, and GERD presented with epigastric discomfort and 3 episodes of coffee-ground emesis for the past day. He had been experiencing intermittent non-radiating epigastric pain for the past 2 weeks, which was sharp and burning in nature. He was on aspirin but not on any NSAID. His last colonoscopy and endoscopy were done more than 10 years ago which showed gastritis. He smokes cigarettes 2 packs/day since the age of 12. He is an occasional drinker but denied any illicit drug abuse. FH is unremarkable for any cancer. On admission, he was hypotensive and tachycardic which improved after receiving fluids. Examination was benign. Labs showed HB of 8.3 (MCV 81), WBC 32 (Abs neutrophil 20.5; lymphocyte 3.2; monocyte 2.6; bands 3.5), platelets 189, BUN/Cr 34/1.5, LDH 663, and PT/aPTT was normal. EGD showed diffuse nodules 4-15 mm with volcano-like ulceration found in the gastric body, fundus, and proximal antrum. The largest ulceration was 10 mm with an adherent clot in the body of the stomach. The clot was removed and a clean based ulcer was found. Biopsies were taken and histopathology of the nodules showed multiple fragments of gastric mucosa with diffuse proliferation of monocytic appearing blast cells, and IHC was positive for CD33, CD45, CD43, muramidase, HLA-DR and thrombomodulin consistent with hematopoietic neoplasm, I.e., myeloid sarcoma of monocytic lineage. He was scheduled for bone marrow biopsy as an outpatient; however, he died before it could be performed. DISCUSSION: As per the literature, the incidence of MS is 2-9% of all acute myeloid leukemia (AML) cases, and only a handful cases of gastric MS are reported in the literature which makes this case extremely unusual. It can be diagnosed before, after, or at the time of presentation of AML. Therefore, clinical suspicion and biopsy are crucial to diagnosis. This case is compelling due to rarity of the disease, its presentation as upper GI bleed without a preceding diagnosis of any hematologic malignancy, and finding of diffuse nodules with volcano-like ulcers on endoscopy.Figure 1.: EGD showing multiple nodules in the stomach.Figure 2.: EGD showing nodule with volcano-like ulcer in the stomach.Figure 3.: EGD showing multiple nodules in the stomach.