Primary cardiac lymphoma (PCL) is a rare extranodal non-Hodgkin lymphoma confined to or predominantly located in the heart, constituting 1-2% of all primary cardiac tumors. The vast majority of patients have diffuse large B-cell lymphoma (DLBCL, 80%). Incidence is markedly increased in immunosuppressed individuals (HIV/AIDS, organ transplant, chronic immunosuppressive therapy). The right atrium is the most commonly involved chamber, but the tendency to infiltrate multiple cardiac chambers is strong — this multiple chamber involvement is the most distinguishing feature of lymphoma. On MR, it appears as an isointense-to-slightly hyperintense, homogeneous mass on T2 with diffusion restriction. Coronary artery encasement without occlusion is a pathognomonic finding. Pericardial effusion is common. Chemotherapy is the primary treatment with good response rates.
Age Range
40-80
Peak Age
60
Gender
Equal
Prevalence
Rare
Primary cardiac lymphoma develops from malignant proliferation of lymphocytes in the heart, which normally does not contain lymphoid tissue. Despite the absence of organized lymphoid tissue in the heart, the existence of cardiac-associated lymphoid tissue (CALT) has been postulated. DLBCL arises from malignant transformation of B-lymphocytes at the germinal center or post-germinal center stage. Immunosuppression, particularly HIV/AIDS and EBV coinfection, plays a critical role in lymphoma development — EBV viral oncoproteins (LMP1) promote B-cell proliferation and activate the NF-kB pathway. Tumor cells spread infiltratively through the myocardium — creating myocyte damage and functional impairment. Lymphoma cells encasing coronary vessels without occluding them indicates that the tumor grows from the perivascular space infiltrating the adventitia but preserving the endothelial barrier. Low T2 signal on MR results from the high nuclear/cytoplasmic ratio of lymphoma cells and limited extracellular water content. Diffusion restriction reflects high cellularity and tight cellular packing restricting movement of intracellular water molecules.
Cardiac lymphoma encasing coronary arteries without occlusion is a pathognomonic finding. Lymphoma cells grow from the perivascular space infiltrating the adventitia of coronary arteries but preserve the intima and media, so the lumen remains patent. This finding reflects lymphoma's infiltrative but non-destructive growth pattern. Angiosarcoma and metastases can invade coronary arteries causing occlusion or create stenosis from compression. On CT angiography, visualization of contrast-filled patent coronary lumen within the tumor mass most reliably demonstrates this finding. Clinically, the absence of acute coronary syndrome despite expected coronary occlusion supports this mechanism.
On T2-weighted sequences, cardiac lymphoma shows isointense or slightly hyperintense homogeneous signal relative to myocardium — does NOT demonstrate marked T2 hyperintensity ('light bulb') like hemangioma. This low-to-intermediate T2 signal reflects the high cellularity and limited extracellular water content of lymphoma. Its homogeneous texture differs from the heterogeneous T2 pattern of angiosarcoma (hemorrhagic areas). In multiple chamber involvement, all lesions show similar T2 signal characteristics — homogeneous infiltrative growth pattern. As necrosis is rare, signal heterogeneity is minimal.
Report Sentence
Isointense-to-slightly hyperintense homogeneous signal in the mass infiltrating multiple cardiac chambers on T2-weighted sequences, consistent with lymphoma.
On diffusion-weighted imaging (DWI), cardiac lymphoma shows marked diffusion restriction — hyperintense signal at high b-values (b=800-1000 s/mm²) and low signal on ADC map (low ADC value, typically <1.0 × 10⁻³ mm²/s). This finding reflects the high cellularity and tight cellular packing of lymphoma. Diffusion restriction is distinctly different from other cardiac masses (hemangioma, lipoma, myxoma) and is a strong clue in differential diagnosis. In treatment response assessment, increase in ADC values indicates favorable response (cell death → increased free water → ADC increase).
Report Sentence
Marked diffusion restriction in the mass on DWI (ADC: X × 10⁻³ mm²/s), consistent with high cellularity, lymphoma should be primarily considered.
On contrast-enhanced MR, cardiac lymphoma shows homogeneous to mildly heterogeneous enhancement. Enhancement degree is moderate — different from the intense heterogeneous enhancement of angiosarcoma and the progressive fill-in pattern of hemangioma. In large tumors, minimal central necrosis areas may appear as non-enhancing low signal regions but are not as prominent as in angiosarcoma since hemorrhagic necrosis is rare. Pericardial involvement — diffuse or nodular thickening and enhancement — should be assessed. Coronary artery encasement by the tumor is best demonstrated on contrast-enhanced imaging.
Report Sentence
Homogeneous to mildly heterogeneous moderate enhancement in the mass on contrast-enhanced imaging, consistent with lymphoma.
On contrast-enhanced CT, cardiac lymphoma appears as a soft-tissue density, homogeneous to mildly heterogeneous enhancing, infiltrative mass involving multiple chambers. The most characteristic CT finding is coronary artery encasement by the tumor without occlusion — this finding reflects lymphoma's perivascular growth pattern and is pathognomonic. Pericardial effusion and pericardial thickening frequently accompany. CT angiography can clearly assess the course of coronary arteries within the tumor and lumen patency. Mediastinal lymphadenopathy and pleural effusion may accompany.
Report Sentence
Infiltrative mass involving multiple cardiac chambers on contrast-enhanced CT encasing coronary arteries without occlusion — pathognomonic finding for lymphoma.
On FDG PET-CT, cardiac lymphoma shows intense and homogeneous FDG uptake (SUVmax usually >10-15). The aggressive metabolic nature of DLBCL causes high glycolytic activity. Unlike angiosarcoma, uptake is homogeneous — since necrotic/hemorrhagic areas are rare, homogeneous distribution is expected. PET-CT is critical for staging and treatment response assessment: extracardiac disease screening (lymph nodes, bone marrow), post-chemotherapy PET negativity (Deauville score) indicates complete response. Myocardial suppression protocol (18-hour fasting + high-fat diet) is mandatory to minimize physiological myocardial uptake.
Report Sentence
Intense homogeneous FDG uptake (SUVmax: XX) in the mass involving multiple cardiac chambers on FDG PET-CT, consistent with lymphoma.
Criteria
80% of cases; large, pleomorphic B-lymphocytes; CD20+, CD79a+; high Ki-67 proliferation index (>40%); aggressive clinical course
Distinct Features
Most common subtype. Can respond well to R-CHOP chemotherapy (50-60% response rate). May be EBV-associated in immunosuppressed patients (especially HIV). CD20 positivity enables rituximab targeted therapy. Germinal center B-cell (GCB) subtype has better prognosis than non-GCB.
Criteria
Small-to-medium, uniform B-lymphocytes; starry-sky pattern (tingible body macrophages); c-MYC translocation; Ki-67 ~100%; very rapid growth
Distinct Features
Rare cardiac subtype. Strong association with HIV/AIDS. One of the fastest growing human tumors (doubling time <24 hours). High risk of tumor lysis syndrome — pre-treatment preparation critical. Requires intensive chemotherapy (DA-EPOCH-R, HyperCVAD). Prognosis worse than DLBCL.
Criteria
Small, cleaved B-lymphocytes; follicular pattern; BCL2 translocation; low Ki-67 (<30%); indolent course
Distinct Features
Very rare in cardiac location. Diagnosis may be delayed due to slow growth. Watch-and-wait or rituximab monotherapy may be sufficient. Risk of transformation to DLBCL exists (2-3%/year). FDG PET uptake may be lower than DLBCL. Prognosis better than DLBCL.
Distinguishing Feature
Angiosarcoma is right atrium dominant (80%), T1 hyperintense (hemorrhage), heterogeneously enhancing, aggressive tumor with pericardial invasion. Lymphoma shows multiple chamber involvement, T1 isointense (hemorrhage rare), homogeneous enhancement, and diffusion restriction. Angiosarcoma invades and may occlude coronary arteries; lymphoma encases coronary arteries without occlusion.
Distinguishing Feature
Cardiac metastasis occurs with known primary malignancy, usually with pericardial dominant involvement. Primary cardiac lymphoma presents without known extracardiac lymphoma history (if known lymphoma exists, classified as 'secondary cardiac involvement'). Metastasis typically shows heterogeneous enhancement and diffusion restriction is variable. Coronary encasement is not expected in metastasis.
Distinguishing Feature
Rhabdomyosarcoma is a rare primary cardiac sarcoma typically seen in children and young adults. More common in left heart chambers. May be hyperintense on T2 but diffusion restriction is less pronounced. Multiple chamber involvement and coronary encasement are findings specific to lymphoma. Biopsy and immunohistochemistry (desmin, myogenin positive vs CD20, CD79a positive) provide definitive differentiation.
Urgency
highManagement
chemotherapyBiopsy
NeededFollow-up
Kemoterapi sonrası interim ve end-of-treatment PET-BT (Deauville skoru). Tam yanıt sonrası 3-6 aylık aralıklarla MR takibi 2 yıl. HIV+ hastalarda HAART ile birlikte.Primary cardiac lymphoma is a rare malignant tumor treated with chemotherapy — surgery is not indicated as primary treatment (unlike angiosarcoma). Histopathological diagnosis is critical: endomyocardial biopsy (EMB) or pericardial fluid cytology is preferred; flow cytometry and immunohistochemistry (CD20, CD79a, Ki-67) are mandatory for subtyping. Standard treatment for DLBCL is R-CHOP (rituximab + cyclophosphamide, doxorubicin, vincristine, prednisone) chemotherapy. Chemotherapy response rates are 50-80% and complete remission is possible. Radiotherapy may be considered for consolidation. Pericardial tamponade requires emergent pericardial drainage. In immunosuppressed patients (HIV), initiation of HAART and immune reconstitution is critical. Surgery is performed only for diagnostic biopsy or hemodynamic emergency (obstruction). Median survival with treatment is 12-24 months; 5-year survival can reach 30-40% in cases achieving complete remission.
Cardiac lymphoma, while rare in primary form, has increased risk in immunosuppressed patients (HIV/AIDS, post-organ transplantation). Secondary cardiac involvement is seen in 20-25% of disseminated lymphoma. Surgical resection is generally not performed; chemotherapy (such as R-CHOP) is the primary treatment and good response can be achieved — this distinguishes it from other cardiac malignancies. Diffusion restriction and T2 hypointensity on MRI are key diagnostic findings. Coronary artery encasement without occlusion is nearly pathognomonic. Histopathological confirmation via pericardiocentesis cytology and/or endomyocardial biopsy is required. FDG PET/CT is important for staging and treatment response assessment.