This case represent a rare presentation of DLBL, as mass inside the right atrium was the first presentation. Initial clinical picture before CT scan was going with many differential diagnosis. It includes atrial myxoma as our initial thought, rhabdomyosarcoma, atrial thrombus, and lymphoma. Clinical presentations of intracardiac mass are not specific, it includes dyspnea, lower limb swelling, signs of superior vena cava syndrome, intra-cardiac thrombus, peripheral embolization, valvular heart disease, and pericardial effusion (7, 8). Other signs and symptoms suggestive of malignancy like weight loss, night sweats, and fever could be presented. However, it was absent in this case which guided us to think of a benign tumor rather than malignancy.
According to the clinical presentation and initial trans-thoracic echocardiography of pending cardiac tamponade and hemodynamic instability, our first decision was to stabilize the patient by removing pericardial and pleural fluid. Trans-esophageal echocardiography was done for better visualization, extension and attachment of the atrial mass. It’s well known that transesophageal echo give better information of intracardiac masses than transthoracic echo (2). However, it failed to reveal the origin of the mass. For which CT was done to detect if there is any outside malignancies invading the heart. CT scan found to have effective modality to demonstrate the extension of the mass and the primary lesion (7). Imaging investigations confirmed primary mediastinal mass invading the heart forming intracardiac mass in the right atrium. Direct extension and infiltration of the mass from the mediastinum to the heart is a well known mechanism (9).
Tissue biopsy was the core element in the diagnosis of this patient, thoracotomy was done previously for this purpose. However, less invasive procedures like percutaneous or fluoroscopy guided biopsy are preferred for pathological examination (7). In our case, there was no accessible lymph nodes were seen by CT scan, pericardial and pleural fluid were negative for malignant cells. As the patient is hemodynamic unstable which was mainly from mass obstructing tricuspid valve. After multidisciplinary team discussion, we decided to go for open heart surgery to stabilize her hemodynamic state by relieving the obstruction and also to get biopsy. Intra-operatively, it was unresectable tumor, and biopsy was taken. Histopathology was consistent with primary mediastinal DLBL.
Cardiac involvement by NHL is rare, and to be presented as intracardiac mass is extremely rare. It could be a primary cardiac lymphoma or mediastinal mass with direct extension and infiltration into the right atrium giving a picture of intracardiac mass (3-6). The prognosis of both subtypes are poor due to rapid progression and invasion of the disease with detection usually in the late stage of the disease (10, 11).
The treatment of DLBL with cardiac involvement is based primarily on chemotherapy. First line treatment regimen with R-CHOP has shown a good response rate (12, 13). Other option was R-EPOCH chemotherapy (14). However, as she was symptomatic and after discussion with the patient and family about the side effects and expected outcome. The decision was to start with R-CHOP chemotherapy. Surgery is usually indicated for a patient who is hemodynamically unstable by improving blood flow to the lungs in case of right ventricle outflow obstruction as chemotherapy takes time to give benefit (15).
Regarding the pelvic mass which was seen by CT scan. Ideally, the biopsy should be taken from the mass. However, as we started the patient on urgent chemotherapy as she was severely symptomatic, we deferred further investigation until follow-up. The mass completely resolved by chemotherapy which confirms histopathology of the mediastinal mass.
DLBCL with heart involvement has a very poor prognosis, it has a 10 % survival rate of 9-12 months if not treated (8). Although it has a high mortality rate, it could be cured with intense chemotherapy (16). Post treatment Surveillance should include PET/CT to confirm response and further follow-up imaging as clinically indicated (17). Early relapse or refractory disease managed by further chemotherapy and allogeneic stem cell transplantation (2). Last guidelines recommended routine follow-up for up to 2 years after treatment. If there is no evidence of relapse, life expectancy is similar to the general population (2).