Bladder lymphoma is a rare tumor originating from lymphoid tissue in the bladder wall. Primary bladder lymphoma accounts for <1% of all bladder tumors; secondary (bladder involvement of systemic lymphoma) is more common. The most common histological type is MALT (mucosa-associated lymphoid tissue) lymphoma. It occurs 3-4 times more frequently in women than men; this is explained by higher frequency of chronic cystitis in women and the role of chronic inflammation in MALT lymphoma development. Clinically may present with hematuria, dysuria, and urinary frequency. On imaging, it appears as diffuse or focal bladder wall thickening, submucosal mass, or rarely polypoid lesion. In lymphoma, the bladder mucosa is usually intact (unlike urothelial carcinoma) — this feature is demonstrated on MRI as subepithelial location and intact mucosa.
Age Range
50-80
Peak Age
65
Gender
Equal
Prevalence
Rare
Primary bladder lymphoma most commonly develops as MALT lymphoma. MALT lymphoma pathogenesis is related to chronic antigenic stimulation — chronic cystitis (especially recurrent UTI) triggers organized lymphoid tissue (MALT) formation in the bladder mucosa. Organized lymphoid tissue is normally absent in the bladder mucosa; it is acquired through chronic inflammation. Chronic antigenic stimulation → monoclonal B cell proliferation → low-grade MALT lymphoma. This mechanism is the bladder counterpart of gastric MALT lymphoma (H. pylori-associated). On imaging, lymphoma appears as a homogeneous soft tissue mass because the tumor consists of monotonous small lymphocyte population — homogeneous density and enhancement on CT, homogeneous signal characteristics on MRI reflect this histological homogeneity. Lymphoma grows in the submucosal layer of the bladder wall and elevates the mucosa but usually does not invade it — seen as intact mucosal line on MRI. Prominent diffusion restriction on DWI is due to high nuclear-cytoplasmic ratio and tight cell packing of lymphoid cells.
Submucosal mass showing marked diffusion restriction (ADC <0.7) with preserved intact mucosal line in the bladder wall is highly characteristic of bladder lymphoma. Urothelial carcinoma invades mucosa and disrupts the mucosal line; in lymphoma, mucosa is elevated but preserved due to submucosal growth.
Diffuse or focal homogeneous thickening of the bladder wall in portal venous phase. Thickening may be symmetric or asymmetric. Density is at soft tissue value (35-55 HU) and homogeneous. Shows moderate homogeneous enhancement after contrast. Unlike urothelial carcinoma, mucosal irregularity or polypoid structure is minimal. Pelvic and retroperitoneal lymphadenopathy may accompany.
Report Sentence
Homogeneous diffuse thickening of the bladder wall with moderate enhancement is observed; lymphoma should be considered in the differential diagnosis.
Lymphoma in the bladder wall appears as homogeneous mass with intermediate-low signal intensity on T2-weighted images — near muscle signal or mildly hyperintense. Homogeneous signal reflects monotonous cellular structure of tumor. Necrosis or cystic change is rare. Mucosal line is usually preserved — submucosal growth pattern.
Report Sentence
Homogeneous submucosal mass with intermediate signal intensity in the bladder wall on T2-weighted images; intact mucosal line is preserved.
Lymphoma in the bladder wall shows marked diffusion restriction on DWI — high signal intensity with very low values on ADC map (0.5-0.7 × 10⁻³ mm²/s). This is due to high cellularity and tight packing of lymphoid cells. Diffusion restriction is the most sensitive MRI finding of lymphoma and enables detection of even small lesions.
Report Sentence
The mass in the bladder wall shows marked diffusion restriction on DWI with very low ADC values; lymphoma diagnosis should be strongly considered.
Lymphoma shows homogeneous, moderate enhancement on contrast-enhanced MRI. Enhancement pattern is homogeneous — necrosis, cystic change, or ring enhancement pattern is not expected. This homogeneous enhancement pattern distinguishes from heterogeneous enhancement of urothelial carcinoma and rim enhancement of inflammatory pathologies.
Report Sentence
The mass in the bladder wall shows homogeneous moderate enhancement on contrast-enhanced images; homogeneous enhancement pattern is consistent with lymphoma.
Hypoechoic, homogeneous submucosal mass in the bladder wall on B-mode ultrasonography. Mucosa overlying the mass is thin and smooth. Mass margins may be smooth or lobulated. Shows minimal to moderate vascularity on Doppler. US sensitivity is lower than MRI but may be the initial detection tool.
Report Sentence
Hypoechoic homogeneous submucosal mass in the bladder wall with intact mucosal covering on ultrasonography; lymphoma should be considered in differential and MRI recommended.
Accompanying pelvic, retroperitoneal, and/or other regional lymphadenopathy in secondary bladder lymphoma — seen as low-density homogeneous nodes. Splenomegaly and hepatomegaly may accompany. When systemic lymphoma involvement is considered, staging with whole-body CT or PET-CT is required.
Report Sentence
Pelvic and retroperitoneal lymphadenopathy accompanying bladder wall thickening is observed; systemic lymphoma involvement should be investigated.
Criteria
Most common primary bladder lymphoma type. Low-grade B-cell lymphoma. Develops on background of chronic cystitis.
Distinct Features
Indolent course, tendency to remain localized, good prognosis. Treatment with surgery, radiotherapy, or chemotherapy.
Criteria
Aggressive lymphoma. Primary or secondary bladder involvement. Rapid growth.
Distinct Features
Larger mass, may be heterogeneous, may contain necrosis. More aggressive enhancement. Requires systemic chemotherapy (R-CHOP).
Criteria
Bladder involvement of systemic lymphoma. More common than primary bladder lymphoma.
Distinct Features
Widespread lymphadenopathy, splenomegaly, other organ involvement accompany. Requires PET-CT staging. Systemic chemotherapy is primary treatment.
Distinguishing Feature
Urothelial carcinoma invades mucosa showing polypoid mass or mucosal irregularity; in lymphoma mucosa is intact. Stalk sign and early enhancement characteristic of urothelial carcinoma. Both show diffusion restriction on DWI but ADC is lower in lymphoma.
Distinguishing Feature
Cystitis may show diffuse wall thickening but no focal mass. Diffusion restriction less prominent than lymphoma on DWI (ADC >1.0). Clinically dysuria and fever predominate. Resolution with antibiotic therapy is distinguishing.
Distinguishing Feature
Leiomyoma appears as markedly T2-hypointense solid mass; lymphoma has intermediate-low T2 signal. Diffusion restriction is mild in leiomyoma on DWI; prominent in lymphoma. Both may show submucosal growth but ADC values are distinguishing.
Distinguishing Feature
Metastasis in setting of known primary malignancy, usually multiple and heterogeneous. Homogeneous structure and intact mucosa characteristic of lymphoma. Necrosis and heterogeneous enhancement more common in metastasis.
Urgency
urgentManagement
medicalBiopsy
NeededFollow-up
specialist-referralBladder lymphoma diagnosis must be confirmed by biopsy. MALT lymphoma treatment options include surgery (TUR or partial cystectomy), radiotherapy, or chemotherapy — prognosis is good due to indolent course (5-year survival >85%). R-CHOP chemotherapy is standard for DLBCL treatment. Systemic treatment applied for secondary lymphoma. PET-CT used for staging and treatment response evaluation.
Bladder lymphoma diagnosis is confirmed by biopsy. Primary MALT lymphoma is an indolent disease with good prognosis — treated with local radiotherapy or chemotherapy. Secondary bladder involvement requires systemic chemotherapy. Surgical treatment is usually not necessary (good response to chemotherapy). Five-year survival for primary bladder lymphoma is >80%.