ABSTRACT
Introduction: Myeloid sarcoma (MS) is a rare localized extramedullary tumor of myeloid precursor cells. Short clinical history: An 11-year-old male presented with nasal bleed, two days; breathlessness and loss of appetite, one month and bilateral nasal blockade for two months. There was no fever. On clinical examination, bilateral cervical lymphadenopathy and hepatosplenomegaly was found. On opening mouth, a pink mass hanging behind the soft palate was noted. Magnetic resonance imaging of head and neck revealed a nasopharyngeal mass in maxillo-ethmoidal sinus. Gross pathology: Excised mass was greenish pink, measuring 2 × 2 × 2 cm. Microscopic examination: Hemogram revealed total leukocyte count 1.2 lac/mm3, hemoglobin 10.1 g/dl, and platelet count 41,000/mm3. Differential count showed 24% blasts with marked left shift. Bone marrow aspirate revealed 27% blasts. No auer rod seen. Cytochemistry showed myeloperoxidase (MPO) positivity. Trephine biopsy showed myeloid hyperplasia with excess blasts. Histopathological examination of lymph nodes and soft tissues showed leukemic infiltration. Immunohistochemistry showed blasts positive for MPO and negative for CD3. On multicolor flow cytometry blasts were positive for MPO, CD34 and CD45, and negative for CD3 and CD79a. A diagnosis of MS with acute myeloid leukemia (AML) was made. Discussion: It is rare in children (1 month-89 years). Any site of body, most commonly skin, lymph node, bone, etc. are affected. Prediction of first appearance of MS or AML was difficult in this case. MS may progress to AML simultaneously or may remain localized, never progressing to AML. Conclusion: Any extramedullary tumor showing myeloid precursor cells, should be investigated for MS, easily misdiagnosed as solid tumors.