Myeloid sarcoma presenting as intestinal obstruction: A case report of the first presentation of acute myeloid leukemia.

Introduction And Importance: Myeloid sarcoma (MS), a rare extramedullary tumor composed of immature myeloid cells, most commonly affects the skin, lymph nodes, and gastrointestinal tract. Rarely, it presents in isolation or in pediatric patients. Misdiagnosis is frequent due to its morphological similarity to lymphomas and lack of clinical context. Early identification is crucial as MS often precedes or accompanies acute myeloid leukemia (AML) and requires immediate treatment.

Case Presentation: A two-and-a-half-year-old female presented with fever, oral ulcers, abdominal pain, and bleeding per rectum. Imaging revealed ileo-ileal intussusception, necessitating emergency surgery. Intraoperatively, a large lymph node and gangrenous bowel segment were resected. Histopathology showed diffuse infiltration by atypical mononuclear cells. Immunohistochemistry revealed positivity for LCA, MPO, CD13, CD33, BCL2, and CD56. A diagnosis of MS was confirmed. Subsequent hematological evaluation revealed AML-M5 with 90 % blasts, and a c-KIT exon 17 mutation. The patient responded well to induction chemotherapy (COG protocol) and remains in remission on consolidation therapy.

Clinical Discussion: Gastrointestinal MS is uncommon, especially in pediatric patients. AML-M5 with monocytic differentiation and CD56 expression is associated with increased risk of extramedullary involvement. The presence of c-KIT mutation may indicate aggressive disease and poor prognosis. Accurate diagnosis requires immunohistochemistry and molecular studies.

Conclusion: This case highlights the importance of considering MS in pediatric patients with intestinal masses. Timely diagnosis using a multimodal approach enables prompt initiation of therapy and may improve outcomes.