Metastatic prostate cancer presenting as a retroperitoneal mass: a case report and review of literature.

Prostate cancer (PCa) is the second most common cancer diagnosed in men globally, after lung cancer. Many patients with PCa are asymptomatic until the tumor has progressed. The prognosis of PCa mainly depends on the presence of metastatic spread. It usually metastasizes to the bone, lung, and liver. Retroperitoneum is an exceedingly rare site for metastatic PCa to occur. We describe a case of a 68-year-old male patient presented for left flank pain and lower limb edema. A retroperitoneal mass was identified on imagery. This mass was found to be due to metastatic prostate adenocarcinoma based on immunohistochemical studies. Knowledge of this atypical presentation of metastatic PCa will reduce the diagnostic delay and allow the appropriate timely treatment.