68Ga‑PSMA PET/CT Facilitates Identification of a Rare Rectal Metastasis From Prostate Cancer

An 86-year-old man underwent radical prostatectomy for prostate adenocarcinoma (T3aN0M0) 5 years ago. He presented with recurrent constipation for 5 months. Pelvic MRI raised suspicion of rectal cancer. Serum prostate specific antigen (PSA) was mildly elevated (9.610 ng/mL). PET/CT revealed thickened rectal walls with no significant hypermetabolism on 18 F‑FDG imaging, but marked radiotracer uptake on 68 Ga‑PSMA imaging (SUVmax = 22.4). Final pathology confirmed metastatic prostate cancer to the rectum. For patients with a history of prostate cancer presenting with rectal occupying lesions, metastatic disease should be included in the differential diagnosis.