Small lymphocytic lymphoma of the prostate mimicking a PIRADS 5 lesion that resolved after systemic treatment

Prostatic PIRADS 4 and 5 lesions on multiparametric MRI typically represent adenocarcinoma with small lymphocytic lymphoma being a rare pathological finding. We report a case of small lymphocytic lymphoma masquerading as PIRADS 4 and 5 lesions with associated lymphadenopathy in a 69-year-old male on active surveillance for low-risk prostate cancer that was subsequently confirmed on targeted and systematic prostate biopsy. Following treatment of lymphoma with ibrutinib, there was complete resolution of the PIRADS lesions on follow-up mpMRI.