Prostate lymphoma is one of the rare malignant tumors of the prostate, accounting for less than 0.1% of all prostate malignancies. Primary prostate lymphoma is extremely rare; the majority of cases represent secondary involvement by systemic non-Hodgkin lymphoma (especially diffuse large B-cell lymphoma — DLBCL). It typically occurs in men aged 60-80 and may present with lower urinary tract symptoms mimicking BPH. Unlike adenocarcinoma, prostate lymphoma generally does not elevate PSA levels; this is an important differential diagnostic clue. On mpMRI, it shows diffuse or focal T2 hypointense signal, marked diffusion restriction, and homogeneous enhancement. Calcification, necrosis, or cystic degeneration are typically absent; this characteristic distinguishes prostate lymphoma from other aggressive tumors. Diagnosis is usually established by TRUS-guided biopsy, and treatment is systemic chemotherapy (such as R-CHOP); surgical intervention is rarely required.
Age Range
50-80
Peak Age
65
Gender
Male predominant
Prevalence
Rare
Prostate lymphoma develops through two distinct mechanisms: primary prostate lymphoma (arising de novo from lymphoid tissue in the prostatic stroma, extremely rare) and secondary prostatic involvement (hematogenous or direct spread of systemic lymphoma). DLBCL is the most common histological subtype, accounting for 70-80% of all prostate lymphomas. Lymphoma cells diffusely infiltrate the prostatic stroma; this infiltration disrupts the normal glandular architecture of the prostate gland but does not directly destroy glandular epithelium — consequently, PSA levels typically remain normal. Diffuse stromal infiltration produces homogeneous hypointense signal on T2-weighted MRI because the dense cellular infiltration reduces free water content, shortening T2 relaxation time. The same dense cellularity (high nucleus-to-cytoplasm ratio, tightly packed cells) restricts Brownian motion of intracellular and extracellular water molecules, producing marked diffusion restriction and low ADC values on DWI. Since lymphoma grows by utilizing existing vascular structures rather than neoangiogenesis, neovascularity is limited — this explains the homogeneous enhancement and absence of necrosis.
Diffuse T2 hypointense signal, marked diffusion restriction, and homogeneous enhancement with prostate enlargement combined with normal PSA level — the absence of PSA elevation unlike adenocarcinoma is the most critical clinico-radiological distinguishing feature of lymphoma. This combination allows differentiation from high-grade adenocarcinoma and prostatitis-related PSA elevation.
Diffuse or focal homogeneous hypointense signal in the prostate parenchyma on T2-weighted images. The lesion may involve the peripheral zone, transitional zone, or both zones. Unlike adenocarcinoma, heterogeneity, calcification, or necrosis are typically absent. In the diffuse form, widespread T2 signal loss is observed throughout the entire prostate gland with obliteration of zonal anatomy. In the focal form, a well-circumscribed, round or lobulated homogeneous hypointense mass is seen.
Report Sentence
Diffuse/focal homogeneous hypointense signal is observed in the prostate parenchyma on T2-weighted images; no necrosis or calcification is identified, and zonal anatomy is obliterated — prostate lymphoma should be the leading consideration.
Markedly hyperintense signal on DWI (at high b values, b=1000-1500 s/mm²) and markedly hypointense signal on ADC map (low ADC values, typically <700 x 10⁻⁶ mm²/s). Diffusion restriction is the most prominent MR finding of lymphoma and is more homogeneous and more pronounced compared to prostate adenocarcinoma. Signal preservation at high b values combined with very low ADC values strongly supports lymphoma.
Report Sentence
Marked homogeneous diffusion restriction is seen on DWI with low ADC values (< 700 x 10⁻⁶ mm²/s) on the ADC map, consistent with dense cellularity; prostate lymphoma should be considered.
Homogeneous and moderate enhancement on dynamic contrast-enhanced MRI (DCE). Unlike the early intense enhancement of adenocarcinoma, lymphoma demonstrates a more balanced and homogeneous enhancement pattern. Necrosis or non-enhancing areas are typically absent. On PI-RADS v2.1, this may be assessed as DCE positive, but the homogeneous enhancement pattern is a distinguishing feature from adenocarcinoma.
Report Sentence
Homogeneous moderate enhancement is observed in the lesion on dynamic contrast-enhanced series; no necrosis or non-enhancing areas are identified — consistent with lymphoma.
Diffuse enlargement of the prostate gland and homogeneous soft tissue density mass on CT. On contrast-enhanced CT, it shows homogeneous enhancement; necrosis, calcification, or cystic components are typically absent. Pelvic and retroperitoneal lymphadenopathy may accompany. Although CT does not provide characterization as detailed as mpMRI, it is valuable for systemic staging.
Report Sentence
On CT, diffuse enlargement of the prostate gland with a homogeneously enhancing soft tissue density mass is observed; no calcification, necrosis, or cystic component is present — consistent with lymphoma.
Diffuse or focal hypoechoic area in the prostate gland on TRUS. The lesion typically appears homogeneously hypoechoic and may have indistinct margins. Calcification or cystic components are typically absent. Doppler may show increased vascularity but without prominent hypervascularity. TRUS findings are nonspecific; they may be indistinguishable from prostatitis or adenocarcinoma. TRUS-guided biopsy is critical for diagnosis.
Report Sentence
A diffuse hypoechoic area is observed in the prostate on TRUS without calcification or cystic component; lymphoma should be considered in conjunction with clinical and laboratory findings.
Markedly increased FDG uptake in the prostate on FDG PET-CT (high SUVmax). As lymphoma is a tumor with high metabolic activity, FDG uptake is prominent and generally more intense than adenocarcinoma. Concurrent pelvic, retroperitoneal, or distant lymph node involvement is consistent with secondary lymphoma. PET-CT is the gold standard for staging and treatment response evaluation.
Report Sentence
Markedly increased FDG uptake is observed in the prostate on FDG PET-CT, consistent with lymphoma in conjunction with concurrent lymphadenopathies.
Criteria
Most common subtype (70-80%). Aggressive clinical course, rapid growth. Diffuse proliferation of large atypical B lymphocytes. CD20 positive, Ki-67 high.
Distinct Features
Diffuse or focal prostate involvement. Marked diffusion restriction and T2 hypointensity on MRI. Good response to R-CHOP chemotherapy.
Criteria
Rare subtype. Indolent clinical course, slow growth. May develop on a background of chronic prostatitis. Small-to-medium lymphocytes, monoclonal B cell proliferation.
Distinct Features
More focal and slowly growing lesion. Diffusion restriction less pronounced than DLBCL. Local treatment (radiotherapy) may be sufficient.
Criteria
Most commonly encountered form. Known history of systemic lymphoma. Concurrent multiple organ and lymph node involvement. Much more common than primary lymphoma.
Distinct Features
Accompanied by widespread lymphadenopathy and extranodal organ involvement. FDG uptake in multiple regions on PET-CT. Prostate lesion regresses with systemic chemotherapy response.
Criteria
Rare. Indolent low-grade B-cell lymphoma. Usually involves the prostate as part of systemic disease. BCL-2 positive.
Distinct Features
Slower growth, less aggressive MR findings compared to DLBCL. Moderate diffusion restriction. Surveillance or rituximab-based treatment.
Distinguishing Feature
Adenocarcinoma typically shows focal, heterogeneous T2 hypointensity with elevated PSA. Lymphoma shows diffuse, homogeneous T2 hypointensity with normal PSA. In PI-RADS v2.1, adenocarcinoma in PZ is assessed by T2 hypointense focal lesion + DWI restriction; lymphoma shows diffuse involvement obliterating zonal anatomy.
Distinguishing Feature
Granulomatous prostatitis can similarly show T2 hypointensity and diffusion restriction, but there is usually a history of BCG treatment or tuberculosis. Peripheral band-like enhancement is more typical in granulomatous prostatitis; lymphoma shows homogeneous enhancement. PSA may be mildly elevated in granulomatous prostatitis.
Distinguishing Feature
Small cell carcinoma may also show diffusion restriction and low PSA but is distinguished by aggressive growth, necrosis, and heterogeneous enhancement pattern. Small cell carcinoma typically forms a large, invasive mass while lymphoma shows more homogeneous and diffuse involvement.
Distinguishing Feature
Acute/chronic prostatitis may show T2 hypointensity and diffusion restriction but typically demonstrates a wedge-shaped or segmental involvement pattern, periprostatic inflammatory changes, and clinical findings such as fever/dysuria. Prostatitis resolves after treatment; lymphoma shows progression.
Urgency
urgentManagement
medicalBiopsy
NeededFollow-up
specialist-referralWhen prostate lymphoma is diagnosed, hematology/oncology consultation is urgently required. Diagnosis must be confirmed by TRUS-guided biopsy; immunohistochemical workup (CD20, CD3, Ki-67) is mandatory. Systemic staging (whole-body PET-CT, bone marrow biopsy) should be performed. Treatment is determined by histological subtype: R-CHOP chemotherapy for DLBCL, local radiotherapy or rituximab for MALT lymphoma. Surgery (radical prostatectomy) is not indicated in lymphoma. Treatment response is assessed by PET-CT (Deauville criteria). Prognosis is acceptable with 60-70% complete remission rate in DLBCL; better prognosis in MALT lymphoma.
Prostatic lymphoma is rare but may have good response to treatment (chemotherapy). Normal PSA is important for differentiation from adenocarcinoma. Secondary involvement (prostatic spread of systemic lymphoma) is much more common than primary lymphoma. Diagnosis is confirmed by biopsy. Staging is done with PET-CT.