18F-DCFPyL Uptake in an Incidentally Detected Follicular Lymphoma by PET/CT Performed for Biochemically Recurrent Prostate Cancer.

A 75-year-old man, treated with curative intent for histopathologically proven prostate cancer (initial prostate-specific antigen, 27 ng/mL; Gleason 4 + 5 = 9) through external beam radiation therapy in 2010 in combination with 3 years of androgen deprivation therapy (leuprorelin), underwent F-DCFPyL PET/CT for biochemical recurrence with a prostate-specific antigen of 4.1 ng/mL in February 2019. Multiple pelvic and some para-aortic lymph nodes showed highly increased F-DCFPyL uptake, suspicious for metastases. Incidentally, a solid mesenteric mass and mesenteric lymph nodes with moderately increased F-DCFPyL uptake were found. Upon histopathological evaluation, this proved to be a low-grade follicular lymphoma.