Non-Hodgkin's primary lymphoma involving the genitourinary tract: histopathological experience from two tertiary hospitals, Western region, Saudi Arabia.

Background: Urinary tract and male genital organ lymphoid neoplasms are uncommon, accounting for less than 5% of all primary extranodal lymphomas. There have only been a few small case series and isolated case reports describing the primary sites and subtypes of these neoplasms. The aim of the study is to investigate the pathological characteristics of patients diagnosed with primary Genitourinary (GU) lymphoma in at two major hospitals.

Material and methods: We obtained cases that were diagnosed with primary GU lymphomas between 2005 and 2020. Pathology and immunohistochemistry slides were retrieved and reviewed, additional immunohistochemical markers were done on selected cases.

Result: Herein we present a study of 11 patients. The mean age at diagnosis time was 46 years (range 24-71 years). Among urinary bladder, and ureter lymphomas, a slight female predominance was noted (3:2). Pathologic lymphoma subtype observed in our study were diffuse large B-cell lymphoma (DLBCL) (36%); mucosa-associated lymphoid tissue (MALT) lymphoma (18%); acute lymphoblastic lymphoma (B-LBL) (9%); high-grade B-cell lymphomas (27%) one of them with histomorphology of Burkitt-like large cell type, and a case of high-grade lymphoma, unclassifiable (9%). At the initial time of presentation, patients were commonly presented with non-specific signs and symptoms.

Conclusion: Even though this study reaffirms the prevalence of DLBCL in GU system, it also sheds light on the variable range of lymphomas that can arise in these sites. The variety of subtypes highlights the significance of thoroughly characterizing lymphoma classifications through ancillary studies such as immunohistochemistry and other molecular/cytogenetic tests if needed, as they are crucial for achieving an accurate pathology diagnosis.