Myeloid Sarcoma of Appendix, Presenting as Acute Appendicitis: A Rare Case Presentation

Myeloid sarcoma is a malignant neoplasm, in which a tumor mass consisting of myeloid blasts with or without maturation occur at an anatomical site other than the bone marrow. Myeloid sarcoma is frequently, but not always, associated with acute myeloid leukemia, chronic myeloid leukemia, and other myelodysplastic disorders. Myeloid sarcomas involving the appendix are uncommon and myeloid sarcoma of the appendix presenting as acute appendicitis is rare. A 64-year-old Omani female presented to the emergency department with 1-day history of acute right lower abdominal pain. She was noted to have leukocytosis and thrombocytopenia in her pre-operative blood investigation, which prompted a 2-week prior history of a single episode of minor nosebleed. Abdominal imaging demonstrated findings suggestive of an acute appendicitis, with differential of mesenteric adenitis and/or focal fat infarction, for which she underwent laparoscopic appendectomy. Surgical pathology of the appendix showed myeloid sarcoma involving the entire appendix including the base. On further investigation, a peripheral blood smear revealed many circulating blasts. Patient was later diagnosed to have acute myeloid leukemia with inv (16) (p13.1 q22) genetic abnormality in a tertiary hospital. Acute appendicitis with leukemic infiltration in form of myeloid sarcoma as the initial manifestation of acute myeloid leukemia has been described in very few cases in the literature, and our case is the first case to be reported in Oman.