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

Abstract

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.

Keywords: CLL, chronic lymphocytic leukemia; Chronic lymphocytic leukemia; GGG, Gleason grade group; Magnetic resonance imaging; PIRADS, prostate imaging reporting and data system; PSA, prostate specific antigen; Prostatic lymphoma; SLL, small lymphocytic lymphoma; Small lymphocytic leukemia; mpMRI, multiparametric magnetic resonance imaging.

Fig. 1

Multiparametric MRI prostate before treatment with ibrutinib (A = T2W, B = DWI). Post-treatment (C = T2W, D = DWI) demonstrates resolution of PIRADS 5 lesions (red arrow) and inguinal lymph nodes (white arrow). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 2

T2W axial MRI pre-post-treatment with ibrutinib demonstrating resolution of a large left pelvic lymph node (white arrow).

Fig. 3

(A) H and E staining of prostatic biopsy showing diffuse moderate lymphoid aggregate consisting of monotonous small and mature lymphocytes. Immunohistochemistry staining positive (B) CD 5 and (C) CD 19, confirming the diagnosis of prostatic lymphoma.