Cannonball metastases as an initial presentation of urothelial bladder carcinoma: a case report and literature review

Urothelial carcinoma is the most common bladder cancer; although pulmonary spread occurs, cannonball metastases are rare and classically linked to germ cell and renal cell tumors. Bladder cancer typically presents with painless hematuria, so respiratory-only presentations can delay diagnosis. We report a 42-year-old man with progressive dyspnea and innumerable bilateral cannonball lesions as the initial manifestation of muscle-invasive urothelial carcinoma, without hematuria. To our knowledge, this is the first such initial presentation reported. This case underscore including urothelial carcinoma in the differential for pulmonary cannonball lesions and pursuing early biopsy and cystoscopic evaluation even in the absence of urinary symptoms.