Urachal Signet Ring Cell Carcinoma: A Clinicopathological Analysis of 28 Cases.

Background: Urachal carcinoma is a rare malignancy comprising less than 1% of all bladder cancers. The signet-ring cell subtype is particularly aggressive and poses significant diagnostic and therapeutic challenges. Methods: A retrospective review of urachal carcinoma cases from 1989 to 2023 was conducted using data from BC Cancer and MD Anderson Cancer Center. The study analyzed 75 patients, including 28 signet-ring cell carcinoma (SRCC) cases and a control group of 47 non-SRCC cases, to compare survival patterns, treatment outcomes, and histopathological features. Results: Clinically, the SRCC subtype was associated with advanced stage at presentation (pT3/pT4) and a higher recurrence rate (82% vs. 53%; p = 0.01). Survival analysis demonstrated worse outcomes for the SRCC cohort, with a five-year cancer-specific survival (CSS) of 39% compared to 64% in the non-signet group (p = 0.053). Partial cystectomy remained the primary surgical approach for both cohorts. Adjuvant chemotherapy was administered more often in SRCC cases (86% vs. 47%). Conclusions: By providing a comprehensive multi-institutional analysis, this study establishes urachal SRCC as a distinct clinical entity with a strong independent prognostic significance. Despite aggressive multimodal management, it carries a poorer prognosis compared to urachal non-SRCC, emphasizing the need for subtype-specific therapeutic guidelines.