Evidence of anorectal involvement by prostate cancer on GA-68-PSMA-11 PET/CT portends inguinal nodal metastasis

Biochemical recurrence was detected in a 68-year-old diagnosed with prostate adenocarcinoma 6 years previously (Gleason 4+4=8, grade group 4, T1bN0M0) status post radiation therapy and 2 years of androgen-deprivation therapy. The patient underwent transurethral resection of the prostate (TURP) for urinary retention with histology demonstrating recurrent prostate adenocarcinoma (Gleason 4+5=9, grade group 5). PSA was 22.95 ng/mL. 68 Ga-PSMA-11 PET/CT subsequently detected an isolated inguinal lymph node metastasis, hypothesized to have occurred via rectotumoral fistulation in the setting of prior pelvic radiation. This case highlights PSMA-targeted PET radiotracers as an essential tool in staging recurrent/metastatic prostate cancer, facilitating identification of atypical sites of metastatic disease.