Left testicular and pulmonary metastases of mucinous adenocarcinoma of the prostate after robot‐assisted radical prostatectomy

INTRODUCTION: We present a case of mucinous adenocarcinoma of the prostate with testicular and lung metastases following robot‐assisted radical prostatectomy, androgen deprivation therapy, and radiotherapy. CASE PRESENTATION: A 73‐year‐old man with a prostate‐specific antigen level of 4.3 ng/mL was diagnosed with prostate cancer. Following the robot‐assisted radical prostatectomy, the pathological diagnosis was mucinous adenocarcinoma of the prostate (pT3bpN0, Gleason score of 4 + 4). Salvage hormonal therapy and irradiation were performed after the prostatectomy. Enlargement of the left testis was noted, and 28 months after prostatectomy, computed tomography detected a left testicular tumor and nodular lesions in the bilateral lungs. The histopathological diagnosis of left high orchiectomy was metastasis of a mucinous adenocarcinoma of the prostate. Chemotherapy with docetaxel followed by cabazitaxel was initiated. CONCLUSION: Mucinous prostate adenocarcinoma with distal metastases following prostatectomy has been managed for longer than 3 years with multiple treatments.