Exploring the genetic landscape of primary marginal zone lymphoma of the urinary bladder

Extranodal marginal zone B-cell lymphoma (MZL) of mucosa-associated lymphoid tissue is the most frequent primary lymphoma of the urinary bladder. To elucidate the disease etiology and correlation with MZLs arising at other anatomical sites, we examined 17 cases (11 female and 6 male) diagnosed with primary bladder MZL between 2005 and 2025. The cohort was characterized through immunohistochemistry (IHC) and fluorescence in-situ hybridization (FISH). High-throughput sequencing (HTS) was performed using a customized lymphoma panel targeting 172 genes, and the resulting data were compared with those from ten other MZL subtypes. Metagenomic whole-genome sequencing was employed to identify bacterial, fungal, parasitic—including protozoal—, and viral agents within the tumor biopsy samples.