A Case of Primary Malignant Lymphoma of the Prostate Gland Presenting as Right Lower Back Pain and Dysuria

Abstract

A 73-year-old man presented with right lower back pain and dysuria. Right hydronephrosis and a large pelvic large mass were seen on computed tomography (CT). Although his prostate-specific antigen (PSA) was 0.5 ng/mL, an irregularly enlarged, stony, hard prostate was palpable on digital rectal examination. A prostate tumor was suspected, and a transrectal prostate biopsy and right transurethral ureteral stent placement were performed. Histological and immunohistochemical studies revealed diffuse large B-cell lymphoma. Positron emission tomography-computed tomography showed abnormal uptake in the stomach, cecum, right obturator lymph nodes, para-aortic lymph nodes, and dorsal left kidney. No abnormal findings were seen on bone marrow histology. Clinical stage IVA was confirmed according to Ann Arbor criteria. The patient achieved a complete response after 8 cycles of combination chemotherapy with rituximab, pirarubicin, cyclophosphamide, vincristine, and prednisolone. (J Nippon Med Sch 2018; 85: 236 240)

An uncommon diagnosis of non-Hodgkin lymphoma on prostatic biopsy

“…In the past decade, there have been only a few reported cases. 6–8 However, in 2005, Chu et al 2 demonstrated that 29 (0.6%) of 4831 prostatectomy specimens examined had foci of lymphoma within either the prostate or lymph nodes. For this patient, there was diagnostic uncertainty as the initial CT and mpMRI scan suggested likely metastatic prostate cancer, but the PSA level and examination findings did not correlate.…”

Differential diagnosis of uncommon prostate diseases: combining mpMRI and clinical information

“…The prostate gland is the site of 0.1% of non-Hodgkin lymphomas (NHLs) and 0.9% of extranodal lymphomas. Primary malignant lymphoma involving the prostate, which is located in the prostate without evidence of systemic lymph node invasion by lymphoma cells, accounts for 0.09% of all prostatic malignancies [ 60 ], and is less common than secondary lymphoma. The serum PSA level of prostatic lymphoma is usually less than 4 ng/mL.…”