Granulocytic sarcoma of the urinary bladder in a pediatric patient.

Granulocytic sarcoma (GS) is a rare tumor consisting of immature cells of granulocytic lineage. It is also called chloroma, referring to the green color of the tumor caused by high levels of myeloperoxidase in the cells. GS is often associated with acute myeloblastic leukemia. We report the case of a 4-year-old boy with a diagnosis of acute myeloblastic leukemia. Abdominal ultrasonography demonstrated a solid, vascularized, heterogeneous, polypoid formation involving the posterior wall of the bladder. Further studies confirmed the etiology of the tumor. On control ultrasonography, a marked decrease in tumor size 15 days after treatment was revealed. We describe the imaging findings in this patient and review the literature about this infrequent entity. Although imaging findings are not specific and considering that extramedullary involvement in leukemia is very sensitive to treatment, inclusion of GS in the differential diagnosis and awareness of the possible sites of occurrence and imaging features is essential to avoid unnecessary therapeutic measures.