European Journal of Cardiovascular Medicine

Primary cardiac tumors are exceedingly rare, with a reported incidence of 0.001–0.03% in autopsy studies¹. Among malignant cardiac tumors, sarcomas are most common, while primary cardiac lymphomas (PCL) constitute only 1–2% of all cardiac tumors and <0.5% of extranodal lymphomas². PCL is most frequently of the diffuse large B-cell lymphoma (DLBCL) subtype³.

Clinical presentation depends on tumor location, size, and degree of obstruction. The right atrium is the most commonly affected site due to its rich lymphatic drainage and venous inflow pattern⁴. Symptoms often mimic pulmonary or cardiac emergencies such as pulmonary embolism, cardiac tamponade, arrhythmias, or intracardiac thrombus⁵.

In this case, the patient presented with a clinical picture strongly suggestive of pulmonary embolism — acute dyspnea, tachycardia, hypotension, and suspicion of clot-in-transit. As per the discharge summary, the patient was initially thrombolysed with alteplase for presumed massive PE before imaging revealed a mass occupying the RA cavity.

Echocardiography is the first diagnostic modality but has limitations in distinguishing thrombus from tumor⁶. CT angiography improves anatomical definition and identifies extracardiac involvement, although differentiation between thrombus and lymphoma remains challenging⁷. In this case, CT showed a non-enhancing lobular lesion involving the right atrium and extending towards the RV inflow, raising suspicion of tumor.

Given the hemodynamic compromise, large size, and high embolic potential, the patient underwent urgent surgical excision. Histopathology is the gold standard for confirmation⁸. Management includes combination chemotherapy (e.g., R-CHOP), though surgery is essential in obstructive cases⁹.

This report presents one of the few documented Indian cases of RA DLBCL presenting as a false PE diagnosis and successfully managed through surgical excision followed by oncology referral.

Clinical Evaluation

• Symptoms: Dyspnea (15 days), fatigue, presyncope

• Vitals: Tachycardia (sinus rhythm), stable hemodynamics on admission

• Examination: Mild pedal edema; RA bruit; no significant murmurs

Initial working diagnosis: massive pulmonary embolism → thrombolysis with alteplase initiated.

Diagnostic Work-up

1. Laboratory Tests

• CBC, KFT, LFT

• PT/INR, APTT

• D-dimer

• Troponin I

• NT-proBNP

  All results contributed to ruling out myocardial infarction and supporting the suspicion of PE vs intracardiac mass.

2. Echocardiography (22 Feb 2025)

• Large RA mass protruding into RV, obstructing tricuspid valve inflow

• Mean gradient: 9 mmHg

• Mild-moderate pericardial effusion (1–1.5 cm)

• LVEF 60%

• No LV, RV dilation; no tamponade

• No segmental wall motion abnormalities

• No tricuspid/mital/aortic regurgitation

3. CT Coronary + Pulmonary Angiography (22 Feb 2025)

• Coronary stents patent

• Lobular RA lesion, non-enhancing, compromising the lumen

• No pulmonary artery thrombus

• No IVC/pelvic vein thrombosis

• Impression: Soft tissue tumor vs thrombus-in-transit

4. Lower Limb Venous Doppler

• No evidence of DVT

5. Holter Monitoring (28 Feb 2025)

• Sinus tachycardia

• Postoperative intermittent atrial fibrillation

Surgical Indications

• Large obstructive RA mass.

• High embolic risk

• Diagnostic uncertainty (clot vs tumor)

• Worsening symptoms

• Prior ineffective thrombolysis

Surgical Procedure

• Midline sternotomy

• Aorto-bicaval cannulation

• Cardioplegia: St. Thomas solution

• RA opened → mass excised completely

• Multiple lobulated, rubbery, vascular mass, attached near tricuspid valve

• Tricuspid valve preserved

• Pericardial drain placed

Histopathology & Immunohistochemistry

• Diffuse large B-cell lymphoma (DLBCL)

• Markers:

  • CD20+, BCL6+, Ki-67 ~70%

  • CD3–, CD10–

Postoperative Management

• 1 day ventilator support

• 1 unit PRBC transfused

• Managed postoperative atrial fibrillation

• Anticoagulation:

  • Apixaban 2.5 mg twice daily

  • Deplatt 75 mg twice daily

• Oncology reference initiated

• Stable discharge on Day 10

Initial clinical evaluation revealed that the patient, a 69-year-old male with prior coronary artery disease and previous thromboembolic events, presented with progressively worsening dyspnea, fatigue, and presyncope. His hemodynamic status on admission suggested a possible pulmonary embolic event, especially in view of his prior DVT/PE history, prompting immediate thrombolysis. However, the lack of clinical improvement led to further imaging, which provided crucial diagnostic clarity.

Echocardiography demonstrated a large, well-defined right atrial mass measuring approximately 4×3×5 cm, which was prolapsing into the right ventricle and significantly obstructing tricuspid inflow. This obstruction produced a mean trans-tricuspid gradient of 9 mmHg, indicating substantial mechanical impedance to diastolic filling. The left ventricular systolic function remained preserved with an ejection fraction of 60%, while a moderate pericardial effusion (1–1.5 cm) was also noted. Importantly, there was no evidence of tamponade physiology, valvular regurgitation, or segmental wall motion abnormality, shifting the differential diagnosis from embolic to mass-related pathology.

CT pulmonary angiography further clarified the anatomical and structural characteristics of the intracardiac mass. The imaging revealed a non-enhancing lobulated lesion occupying the right atrium, without evidence of pulmonary artery thromboembolism. Coronary stents from previous percutaneous coronary intervention were patent, and there was no thrombosis in the inferior vena cava, iliac veins, or pelvic venous system. These findings confirmed the absence of acute PE and highlighted a high-risk intracardiac lesion responsible for the patient’s clinical deterioration.

Given the obstructive nature of the mass and the uncertainty between thrombus versus neoplasm, urgent surgical exploration was performed. Intra-operatively, the lesion appeared multilobulated, rubbery, and highly vascular, arising from the anterior wall of the right atrium near the tricuspid annulus. The mass was excised completely without compromising the tricuspid valve, and no residual lesion was visualized on inspection. The gross morphology strongly suggested a malignant tumor rather than an organized thrombus.

The postoperative period was notable for transient atrial fibrillation, which required antiarrhythmic management but stabilized within 48 hours. Hemodynamic recovery was otherwise smooth, and the patient required only one unit of packed red blood cells. No significant postoperative complications such as low-output syndrome, recurrent effusion, or conduction abnormalities were observed. The patient was started on dual therapy (Apixaban and Deplatt) due to his combined profile of prior PCI, new-onset atrial fibrillation, and postoperative risk.

Histopathological examination confirmed the diagnosis of diffuse large B-cell lymphoma (DLBCL), with strong positivity for CD20 and BCL6, and a high proliferative index (Ki-67 ≈ 70%), consistent with an aggressive subtype of primary cardiac lymphoma. The patient showed good postoperative recovery and was discharged in stable condition on the tenth day, with oncology referral for systemic therapy

Primary cardiac lymphoma is a rare disease with variable presentation. Patients commonly present with dyspnea, chest discomfort, arrhythmias, or signs of superior vena cava obstruction. In our case, the symptoms closely mimicked pulmonary embolism — a diagnosis initially reinforced by patient’s past history and clinical instability.

The discharge summary highlights an important learning point: even after thrombolysis, the patient did not improve, prompting reevaluation. Echocardiography revealed a large RA mass causing obstruction. CT angiography further confirmed the presence of a non-enhancing lobular lesion without pulmonary artery thrombus. This underscores the importance of multimodal imaging for differentiating between thrombus and tumor.

The mass caused significant hemodynamic compromise by obstructing tricuspid inflow. Literature indicates that obstructive RA masses — whether thrombus or tumor — require urgent intervention due to risk of sudden cardiac death¹⁷. In this scenario, surgical excision was mandated.

Histopathology confirmed DLBCL, the most frequent variant of PCL. B-cell markers (CD20+, BCL6+) with high proliferation index (Ki-67 70%) indicated aggressive behavior. Early surgical removal allowed rapid stabilization and timely referral to oncology.

Postoperative atrial fibrillation, a known complication after cardiac surgery, was successfully managed. The patient was discharged stable with dual antiplatelet and anticoagulant therapy due to prior PCI and postoperative AF.

This case illustrates the complexity of diagnosing intracardiac tumors, especially in patients with previous thromboembolic disease. RA lymphoma should be considered when large intracavitary masses fail to respond to anticoagulation or thrombolysis.

Right atrial lymphoma is an exceptionally rare and life-threatening condition that can mimic pulmonary embolism. Early diagnosis using multimodal imaging, prompt surgical excision in obstructive cases, and definitive histopathology are crucial. Multidisciplinary care involving cardiology, cardiac surgery, oncology, and imaging specialists is essential for improving survival.

1. Maleszewski JJ. Cardiac tumors: pathology and classification. Cardiol Clin. 2019;37(4):525-37.
2. Petrich A, Cho SI, Billett H. Primary cardiac lymphoma: an analysis of presentation, treatment, and outcome patterns. Cancer. 2017;123(5):898-906.
3. Carras S, Berger F, Chalabreysse L, Callet-Bauchu E, Cordier JF, Salles G, et al. Primary cardiac lymphoma: diagnosis, treatment and outcome in a contemporary series. Haematologica. 2016;101(8):1043-50.
4. Jeudy J, Kirsch J, Mohammed TL, Arbab-Zadeh A, Brown K, Chung JH, et al. Cardiac masses: CT and MRI evaluation. Radiographics. 2017;37(7):1933-52.
5. Motwani M, Kidambi A, Herzog BA, Uddin A, Greenwood JP, Plein S. MR imaging of cardiac tumors and masses. JACC Cardiovasc Imaging. 2017;10(9):1041-55.
6. Hoey ETD, Shahid M, Ganeshan A, Baijal S, Simpson H, Watkin RW. Cardiac tumors: echo and multimodality imaging. Clin Radiol. 2017;72(4):326-38.
7. O’Donnell J, Mooney J, Walsh K. Clot-in-transit mimicking intracardiac tumor. J Thromb Haemost. 2018;16(9):1981-4.
8. Agha A, Parwani P, Shirani J. Right atrial masses: differential diagnosis and imaging approach. Curr Probl Cardiol. 2018;43(9):315-50.
9. Randhawa VK, Jassal DS. Primary cardiac tumors: echocardiographic evaluation. Echocardiography. 2016;33(5):781-90.
10. Chen Y, He Y, Cai Z, Fan X. Non-Hodgkin lymphoma involving the heart: single-center experience. Radiol Oncol. 2018;52(1):35-42.
11. Basso C, Rizzo S, Valente M, Thiene G. Cardiac masses and tumors. Cardiovasc Pathol. 2016;25(5):426-35.
12. Aquaro GD, Todiere G, Barison A, et al. CMR in cardiac tumors: value and limitations. Eur Heart J Cardiovasc Imaging. 2018;19(2):139-48.
13. Mahmood SS, Fradley MG, Cohen JV, et al. Anticoagulation and arrhythmia management in cardiac tumors. J Card Surg. 2020;35(1):145-52.
14. Bussani R, De-Giorgio F, Abbate A, Silvestri F. Cardiac tumors: autopsy findings in contemporary practice. Virchows Arch. 2019;475(5):641-50.
15. Burazor I, Franco OH, Talker M, et al. Cardiac lymphoma: clinical manifestations and therapy. Int J Cardiol. 2016;203:410-15.
16. Chen W, Blais N, Patel A, et al. Cardiac involvement in diffuse large B-cell lymphoma. Clin Lymphoma Myeloma Leuk. 2020;20(4):e154-60.
17. Rahouma M, Arisha MJ, Elmously A, et al. Surgical resection of cardiac tumors: outcomes and indications. J Thorac Cardiovasc Surg. 2019;157(6):2289-99.
18. Aref S, Osman H, Hafez M, et al. Primary cardiac lymphoma presenting as acute heart failure. Echocardiography. 2019;36(9):1761-5.
19. Poterucha TJ, Kochav J, O’Connor DS, Rosner GF. Cardiac tumors: clinical presentation and management. Curr Treat Options Oncol. 2019;20(8):66.
20. Khariton Y, Krishnan B, Nair V, et al. Non-Hodgkin lymphoma of the right heart: a masquerader. Cardiol J. 2017;24(3):341-4.
21. Kumar N, Agarwal S, Rangappa P. Right atrial mass mimicking thrombus. Indian Heart J. 2018;70(2):300-3.
22. Kothari J, Patel R, Shah A. Cardiac lymphoma mimicking pulmonary embolism. Clin Case Rep. 2017;5(8):1292-5.
23. Li Y, Wei X, Zhang L, et al. CT characterization of cardiac masses. Clin Imaging. 2019;57:54-60.
24. Dinesh Kumar R, Gupta S, Singh A. Primary cardiac lymphoma: Indian experience. Indian J Hematol Blood Transfus. 2021;37(2):345-51.
25. Talwar KK, Kumar AS, Saxena A. Right atrial tumors: Indian case series and management outcomes. Indian Heart J. 2017;69(4):500-6.