A case report of multifocal gastrointestinal myeloid sarcoma without leukemic involvement: an unusual presentation...

Myeloid sarcoma is a rare hematologic malignancy defined by the extramedullary proliferation of myeloid blasts. It may occur without concurrent acute myeloid leukemia, creating a significant diagnostic challenge, particularly when it involves uncommon sites such as the gastrointestinal tract. We report the case of a 43-year-old woman with no relevant comorbidities who presented with a two-year history of epigastric pain and heartburn, later complicated by hematemesis. Imaging revealed a large gastric mass with associated hepatic focal lesions, initially raising suspicion for gastric adenocarcinoma with hepatic metastases. Histopathologic examination of the gastric biopsy showed malignant round cells consistent with a hematolymphoid neoplasm, and immunohistochemistry confirmed the diagnosis of myeloid sarcoma, with strong positivity for CD43 and myeloperoxidase and diffuse expression of CD56 and BCL2. Peripheral blood smear, complete blood count, and bone marrow aspirate showed no overt leukemic involvement. A biopsy from one of the hepatic lesions demonstrated similar histopathologic and immunohistochemical features, confirming multifocal disease. The patient was treated with standard induction chemotherapy using the "7 + 3″ regimen consisting of cytarabine and daunorubicin. During treatment, she developed fever, jaundice, and profound pancytopenia, and on day 12 she suffered sudden cardiorespiratory arrest and died. This case underscores the diagnostic complexity of gastrointestinal myeloid sarcoma, highlights the importance of immunohistochemistry in distinguishing it from other malignancies, and emphasizes the aggressive clinical course and poor prognosis that may occur even in non-leukemic presentations.