Asymptomatic Metastasis to Thyroid Cartilage Detected by 18F-Choline and 64Cu-PSMA PET/CT as a Single Site of Disease Relapse in a Patient With Castration-Resistant Prostate Carcinoma.

Metastatic involvement of the larynx is rare due to the absence of vessels within the cartilaginous tissue. The probability of metastatic spread increases with aging as a result of larynx ossification. The secondary involvement of larynx is more frequently associated with melanoma and renal cell carcinoma. Few observations have been reported also in prostate cancer patients, usually associated with advanced disease and diffuse metastatic bone involvement. We report a case of an 83-year-old man with castration-resistant prostate cancer in whom a metastasis to the thyroid cartilage was the only site of relapse.