Testicular and Bladder Metastases From Prostate Adenocarcinoma 18 Years After Definitive Treatment Despite Undetectable Prostate-Specific Antigen and Negative Prostate-Specific Membrane Antigen Positron Emission Tomography

Secondary tumors of the prostate commonly metastasize to the lymph nodes, bones, and lungs.While the prostate is the most frequent primary source of secondary testicular malignancies, the latter occurs rarely and is usually detected as a mass on examination or ultrasonography.We describe an instance of a 71-year-old patient with a history of T4bN1 Gleason 8 prostatic adenocarcinoma treated with a radical prostatectomy followed by adjuvant radiotherapy, and androgen deprivation therapy (ADT), who remained disease free on follow-up studies for a period of 18 years, until he was evaluated in June of 2024 with right sided orchialgia.His workup, including multiple testicular ultrasounds, was benign, and the patient ultimately underwent a radical orchiectomy for unrelenting pain.Pathologic staining was positive for AE1/AE3 and strongly positive for NKX3.1, with focal CA9 and scant CDX2 positivity without any positivity of placental alkaline phosphatase (PLAP), overall suggestive of metastatic carcinoma of prostatic origin.10 months later, the patient presented with recurrent urinary tract infections (UTIs) and hematuria in association with abnormal cytology and positive fluorescence in situ hybridization (FISH) testing.Initial cystoscopy and bladder biopsies were benign.Surveillance imaging demonstrated asymmetrical thickening of the inferior left bladder wall, and repeat cystoscopy revealed a 3 cm calcified mass at the bladder neck.Tumor pathology demonstrated poorly differentiated adenocarcinoma with focal nuclear staining of NKX3.1, once again consistent with metastatic prostatic carcinoma.This is a rare example of metachronous metastasis to unusual genitourinary structures in a patient with prostate adenocarcinoma 18 years after primary treatment despite a low to undetectable prostate-specific antigen (PSA) and negative surveillance prostate-specific membrane antigen (PSMA) positron emission tomography (PET) imaging.