Primary Versus Secondary Non-Urothelial Tumors Involving the Bladder: A 10-Year Analysis of Clinicopathologic Profiles and Adverse Feature Burden

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BACKGROUND AND OBJECTIVES: Non-urothelial bladder tumors and secondary bladder involvement from extravesical primaries are uncommon but clinically challenging. We compared clinicopathologic patterns between primary non-urothelial tumors and secondaries, and explored correlates of adverse pathologic features to inform diagnostic triage and surgical planning. METHODS: We performed a single-center retrospective cohort (2014-2024) of consecutive bladder lesions meeting WHO 2022 criteria and AJCC 8th staging. Eligible cases were primary non-urothelial malignancies (squamous cell carcinoma (SCC), adenocarcinoma (ADK), small-cell/neuroendocrine (NEC), sarcomatoid) or secondary bladder involvement (colorectal, prostate, cervix, ovary, uterus, breast). Outcomes included advanced pT (≥pT3), lympho-vascular invasion (LVI), perineural invasion (PNI), nodal metastasis, margin status, and composite adverse events. RESULTS: ): secondaries were ADK-dominant (59.1%), whereas primaries were enriched for SCC (38.5%), sarcomatoid (28.8%), and NEC (21.2%). Among secondaries, prostate origin showed the most ominous profile (advanced pT 97.5%, PNI 77.5%, positive margins 64.7%); colorectal cases combined high advanced pT (70.2%) with lower margin positivity (27.6%). Adverse-feature count correlated with pT (ρ = 0.586). CONCLUSIONS: Secondary bladder involvement carries substantially higher adverse-pathology rates than primary non-urothelial tumors, with origin-specific risk gradients (prostate > colorectal ≳ cervix). Rigorous origin adjudication and a margin-focused, anatomy-adapted surgical strategy may improve outcomes; prospective outcome-linked validation is warranted.