Myeloid Sarcoma of Prostate with Urinary Obstruction: An Unusual Presentation of Acute Myelogenous Leukemia in a Child

We describe here a case of myeloid sarcoma of prostate in an 8 year old child who presented with bladder outflow obstruction. Peripheral blood picture was normal and CECT of abdomen and pelvis showed a hypoechoic mass in prostate causing bilateral hydronephrosis. A diagnosis of rhabdomysarcoma of prostate was considered. Bone marrow examination done as a part of metastatic workup revealed 38% blasts which were positive for Sudan Black and myeloperoxidase (MPO) indicating a diagnos is of acute myeloid leukemia (AML) - (FAB M2 subtype). An ultrasound guided biopsy of the prostate mass showed myeloblasts in a stroma of spindle cells which on immunohistochemistry (IHC) were positive for MPO. Flowcytometry was positive for CD 33 and CD 34. This mass completely disappeared after a week of induction chemotherapy using cytosine arabinoside (Ara-C), daunorubicin and etoposide with complete resolution of symptoms. Granulocytic sarcomas are rare in prostate; only 9 cases reported in adults. We could not find similar report in children. Granulocytic sarcoma should be considered in differential diagnosis of mass in anuric children.