Marrow to Bowel or Bowel to Marrow: Intestinal Myeloid Sarcoma Presenting With Acute Obstruction.

Myeloid sarcoma (MS) is an extramedullary tumor composed of immature myeloid precursor cells and represents a tissue manifestation of acute myeloid leukemia (AML). It may occur concurrently with AML, precede marrow disease, or present at relapse. Gastrointestinal (GI) involvement is uncommon and frequently poses a diagnostic challenge due to morphological overlap with lymphoid and other GI malignancies. We report the case of a 38-year-old man presenting with acute intestinal obstruction secondary to a duodenal-jejunal mass. Histopathological examination demonstrated diffuse submucosal infiltration by monomorphic abnormal cells, initially raising a differential diagnosis of lymphoma or poorly differentiated malignancy, intestinal tuberculosis, or gastrointestinal stromal tumor. Immunohistochemistry revealed strong myeloperoxidase positivity, with negativity for epithelial, lymphoid, and neuroendocrine markers, supporting myeloid lineage. Peripheral blood examination showed leukocytosis with circulating blasts and monocytic precursors. Multiparametric flow cytometry was suggestive of AML with monocytic differentiation, establishing the diagnosis of intestinal MS with concurrent AML. The present case highlights the rarity of MS presenting as an acute abdomen and surgical emergency with diagnostic challenges to the surgeon. Accurate diagnosis relies on keeping a high index of clinical suspicion, along with a multidisciplinary approach. Early identification is critical, as MS requires prompt AML-directed systemic therapy rather than localized surgical treatment.