This paper aims to discuss and highlight imaging findings of non-urothelial bladder tumors (NUBT) and how they differ from the imaging findings of typical urothelial carcinomas by presenting cases of our institution, alerting radiologists to consider these differential diagnoses in case of atypical imaging findings.

Urothelial carcinoma is the most frequent bladder cancer, accounting for about 95% of cases. Primary non-urothelial bladder tumors are rare, representing around 5% of all bladder lesions combined, and markedly differ from urothelial carcinoma in terms of diagnosis, management, treatment, and prognosis. However, the symptoms of these rarer tumors often overlap with those of urothelial tumors. In this context, imaging plays an essential role in indicating the non-urothelial nature of these lesions.

Among these rare lesions, adenocarcinoma, squamous cell carcinoma, and small cell carcinoma have a more aggressive biological behavior and are often found in advanced stages at diagnosis. Despite having a better prognosis, other even rarer lesions, such as paraganglioma, lymphoma, and myxofibrosarcoma, also require early diagnosis, impacting patients'...

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As the systematic investigation of most non-urothelial bladder tumors is limited by the rarity of these lesions, it is essential that the radiologist is familiar with some of the rarer differential diagnoses, allowing more agility in the diagnosis, clinical management and follow-up of these patients.