Primary follicular lymphoma of the prostate co-existing with grade group 5 prostatic adenocarcinoma and presenting as a PI-RADS lesion 4 on mpMRI.

Primary prostatic lymphoma is an exceedingly rare entity comprising less than 0.09% of all prostatic cancers with follicular lymphoma making up only 12% as a subset. To our knowledge, primary follicular lymphoma co-existing with high grade prostatic adenocarcinoma presenting as a PI-RADS lesion 4 on mpMRI has not been previously described. We report the case of a 73-year-old male who presented with mildly elevated PSA and lower urinary tract symptoms. Prostate needle biopsy revealed low grade follicular lymphoma juxtaposed with high grade prostatic adenocarcinoma. The patient has been treated with radiation therapy for adenocarcinoma and is under observation for lymphoma progression.