Primary signet-ring carcinoma of the urinary bladder: A case report and mini review of literature.

Primary signet ring cell carcinoma (SRCC) of the urinary bladder is an exceptionally rare and aggressive malignancy. We report a case of a 60-year-old man presenting with painless gross hematuria, urinary frequency, and dysuria. Imaging and cystoscopy revealed a bladder lesion, while histopathology demonstrated diffuse signet ring cell infiltration with detrusor muscle invasion, confirming muscle-invasive disease. Extensive investigations, including upper and lower gastrointestinal endoscopy, chest radiography, and prostate biopsy, excluded secondary malignancies. Despite the lack of immunohistochemistry, diagnosis was established through clinicopathologic correlation. This case highlights the importance of thorough evaluation for accurate diagnosis and appropriate management.