Myeloid sarcomas of the genitourinary tract: A multi-institutional study of sixteen tumors with review of literature.

Myeloid sarcoma (MS) is a rare extramedullary manifestation of acute myelogenous leukemia (AML). Leukemic involvement of the genitourinary (GU) tract is extremely rare with only 2-7 % of the reported MS cases involving the kidney or urinary system. Patients with urinary tract MS can present with signs and symptoms related to urinary tract obstruction, hematuria, or urinary retention. Despite its rarity, MS can be diagnosed correctly with the use of ancillary tests such as immunohistochemical (IHC), flow cytometry and/or molecular testing. Right diagnosis is essential for selection of appropriate therapy. We performed a retrospective multi-institution study of 16 cases of MS of GU tract reported between 2010 and 2024. Clinicopathological, IHC, flow cytometric and molecular data were analyzed. The average age of patients in our cohort was 38 years with a male: female ratio of 5.3:1. Most of the cases were in the bladder (13/16) followed by ureter (2/16) and kidney (1/16). All cases presented as a relapse of AML and hematuria was most common clinical presentation (60 % cases). The average size of tumor was 3.3 cm. Immunohistochemically, CD45, CD34, CD117, MPO were positive in all cases. FLT3- ITD and NRAS mutation was noted in 13.3 % respectively. 8/16 patients died of myeloid sarcoma. Our study provides a comprehensive largest-to-date case series of the extremely rare MS of the GU system. Most common location was bladder. All cases were correctly diagnosed using ancillary testing and showed poor prognosis with a high mortality rate (46.6 %).