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Acute Myeloid Leukemia (AML) is a potentially fatal disease, more common in an elderly population. The American Cancer Society estimates 21,450 new cases of AML and 10,920 deaths from AML in the United States in 2019. This malignancy originating in the Bone Marrow (BM), usually presents with peripheral blood (PB) abnormalities. Rarely, AML, particularly monoblastic variants can present with extramedullary disease. Here we describe a case of AML presenting with diffuse lymphadenopathy and a biopsy revealing myeloid sarcoma. A 53 years old male developed diffuse lymphadenopathy. Failure of outpatient empiric antibiotic treatment prompted right cervical lymph node biopsy. Lymph node architecture was distorted by the presence of malignant monocytic myeloid cells. Both the peripheral blood and bone marrow were involved by AML with monocytic features. The monoblasts count was 14% in PB and 24% in BM and the promonocyte count was 12% in PB and 26% in BM. Complete Blood Count showed total white blood cell count of 31,700, hemoglobin 11.8, monocytes 22.5% and platelets 122,000. Flow cytometry of the bone marrow demonstrated a blast population with positive expression of cMPO, CD33, CD13, CD11b, HLA-DR, CD64, CD14 and CD4; and negative for CD34, CD117, nTdT, cCD3, cCD79a. Fluorescence in situ hybridization study was positive for MLL gene rearrangement. Molecular study was positive for IDH1 mutation, and negative for IDH2, RUNX1, FLT3 mutations. Further laboratory analysis was significant for lactate dehydrogenase 346, uric acid 8.6, prothrombin time 13.6, INR 1.2, partial thromboplastin time 33.5 and fibrinogen 293. Computed tomography of chest, abdomen, pelvis with contrast revealed extensive adenopathy with enlarged bilateral supraclavicular, bilateral axillary, mediastinal, bilateral hilar, upper abdominal, periaortic retroperitoneal, pelvic and inguinal lymph nodes. Hepatosplenomegaly was also reported. The term Myeloid Sarcoma (MS) is used when leukemic cells are present outside the bone marrow and peripheral blood. MS tends to oocur more commonly in middle aged males (male-to-female ratio, 2:1, median age, 56 years). The Mayo Clinic Experience of 96 cases demonstrated 27% of patients had no bone marrow involvement, and 69% of patients had primary bone marrow disease. Extramedullary involvement can occur prior to, simultaneously, or after bone marrow involvement. Just as in our case this is an important feature for clinicians to remember so that they may recognize this rare entity early. |
