A Rare Case of Sensory Neuropathy Associated with Transitional Cell Carcinoma of the Bladder.

Malignancies can trigger an autoimmune response against the nervous system and manifest as paraneoplastic neurological syndromes (PNS). Initial symptoms of PNS may develop up to 5 years prior to the diagnosis of the underlying malignancy. We report a rare case of PNS associated with transitional cell carcinoma of the bladder in a 70-year-old male with a 6-month history of rapidly progressive symmetric sensory neuropathy. Peripheral neuropathy serological workup was unremarkable. A paraneoplastic neuropathy panel revealed anti-Hu autoantibodies. Further evaluation with a whole-body PET scan could not identify the primary malignancy, but it showed hypermetabolic hilar lymph nodes. An endobronchial ultrasound biopsy of the hilar lymph nodes was negative for cancer. The patient developed painless hematuria 2.5 years after the onset of the sensory neuropathy. Cystoscopy with biopsy revealed non-muscle-invasive transitional cell carcinoma of the bladder. Progression of the sensory neuropathy stopped after tumor resection. This case highlights the importance of a diligent and systematic approach to diagnose PNS. A relentless search is often required to detect PNS-associated occult malignancies.