Diagnosis and treatment of Primary Cardiac Lymphoma: A Case Report

Background: Primary cardiac lymphoma (PCL) is an extremely rare cardiac tumor and progresses rapidly, which often has short median survival time and poor prognosis unless diagnosed and treated in time. Case presentation: A 61-year-old man was admitted to hospital with repeated chest tightness and pain for 3 days and the right atrial mass by ultrasonography in the other hospital for 1 day. The echocardiography revealed an irregular hyperechoic mass in the right atrium with the size of the mass is about 5.3cm*4.3cm. Partial resection of right atrial tumor under general anesthesia and cardiopulmonary bypass was performed. After operation, enhanced chest computed tomography (CT) showed a mild enhancement mass in the right atrium. The histopathological examination revealed diffuse large B cell lymphoma. After careful examination, PCL was diagnosed and chemotherapy of low dose R-CHOP for 6 courses were used. After the last course, enhanced CT examination showed that the tumor almost disappeared and the patient's symptoms improved signicantly. Conclusion: PCL is a extraordinarily rare disease with poor prognosis, and it is necessary to improve the awareness of this disease.Prompt diagnosis and timely chemotherapy in combination with surgery could lead to excellent clinical outcomes of the patient with PCL.


Background
Primary cardiac lymphoma (PCL) is an extremely uncommon cardiac tumor, which accounting for only 1.3% of all cardiac tumors and only 0.5% of all extranodal lymphomas [1,2]. The incidence of PCL is low, but once the disease starts, it will progress rapidly and the median survival time is only about 12 months, so timely diagnosis and treatment are extremely important [3].

Case Presentation
Herein we present a case of a 61-year-old man who was referred to our hospital. The patients had a history of repeated chest tightness and pain for 3 days and found a right atrial mass by ultrasonography in the other hospital for 1 day. The patient had no complaints of the B symptoms (night sweats, body temperature above 38 degree centigrade or weight loss of more than 10% of body within six month). The echocardiography revealed an irregular hyperechoic mass in the right atrium with the size of the mass is about 5.3cm*4.3cm, which is connected to the lateral wall of the right atrium without obvious movement ( Fig. 1). After admission, partial resection of right atrial tumor under general anesthesia and cardiopulmonary bypass was performed. During the operation, we can see the mass in the right atrium with a diameter of about 6cm, fused with the myocardium and presented invasive growth. The mass has a jelly sh-like texture, protruding from the right atrial and blocking the opening and closing of the tricuspid valve. The mass was partial excised along the edge of the tumor for biopsy, and also can relieve the effect of the mass on the activity of the tricuspid valve. After the surgery, careful examinations were performed, including enhanced CT and positron emission tomography-computed tomography (PET-CT).
The patient was started chemotherapy with low dose of R-CHOP for 6 courses. The symptoms of panic and chest distress gradually disappeared as the chemotherapy treatment continued and the mass gradually smaller. After 7 months, the treatment continued for ve cycles and at the last chemotherapy, the patient underwent another enhanced CT examination, which showed the tumor almost disappeared (Fig. 5). The symptoms of patient disappeared completely after 6 courses of chemotherapy.

Discussion
PCL is de ned as extranodal lymphoma that occurs only in the heart and pericardium. On the other hand, when there is extranodal lymphoma in the heart with asymptomatic extracardiac localized lesions can also be diagnosed as PCL [4]. PCL belongs to non-hodgkin's lymphoma, and its main pathological type is diffuse large B cell lymphoma. The most common site of PCL is right atrium, followed by right ventricle, left ventricle, left atrium and atrial septum. Our patient was diagnosed as PCL, because there was no evidence of lymphoma present in any other organ of him and his histological exams consistent with diffuse large B cell lymphomas. Symptoms of PCL are usually nonspeci c and associated with the extension of the tumor, differing from lymphoma located in other organs, PCL often causes cardiovascular events, such as heart failure, dyspnea, arrhythmia and pericardial effusion.
Although de nitive diagnosis is con rmed by pathology, multimodality imaging optimizes the diagnostic evaluation. Echocardiography is often the preferred imaging method, but CT imaging can provide preferable soft tissue contrast and anatomic information. On CT image, PCL is usually presented as a single or multiple iso-density or low-density mass which in ltrating into the myocardium, with slight enhancement on contrast-enhanced scans. Meanwhile, coronary artery can be seen oating in the mass, which is a typical imaging manifestation of lymphoma called vascular oating sign [5,6]. Nuclear medicine imaging (PET-CT) may assist in differentiate from other more common cardiac tumors, high uptake is the speci c manifestation of PCL [7]. Previous study has shown that SUV values of PCL patients was signi cantly higher than those of patients with other cardiac malignancies (such as metastatic tumors, sarcomas) and benign tumors [8].
The main treatment of PCL is the combination of surgery and chemotherapy [9]. It is almost impossible to remove the tumor by single surgery, the purpose of surgery is to alleviate clinical symptoms, remove mechanical obstruction when hemodynamics is disturbed, and provide basis for chemotherapy. It also provides pathology information which could make us determine the pathological type of the tumor by biopsy [10]. Chemotherapy is currently described as the most effective treatment for PCL, and it has been reported in the literature that 61% of patients can get remission from chemotherapy alone [11].
Chemotherapy with CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) is a classic treatment for Hodgkin's lymphoma and it's also used for the treatment of PCL. In this case, the tumor hindered the normal opening and closing of the tricuspid valve, resulting in the interference of venous blood ow to the pulmonary artery. Therefore, partial tumor resection was performed to remove the effect of the tumor on the tricuspid valve activity and correct hemodynamics. After R-CHOP treatment for 6 courses, the tumor was signi cantly smaller and the patient had an excellent clinical outcomes.
The prognosis for patients with PCL is usually poor, and the median survival is only about 12 months. Benign tumors such as cardiac myxoma account for a high proportion of primary cardiac tumors, while PCL account for only 1.3% of primary cardiac tumors. Due to the rarity of PCL and atypical radiologic, people usually cannot get a complete recognition of it, which maybe the reason of unable to diagnose in time. PCL is also considered as an acute tumor because of the severe in ltration of the myocardium and the rapid progression of the tumor. Late diagnosis and rapid evolution of the tumor are major factors causing the poor prognosis.

Conclusion
PCL is a very rare disease with poor prognosis. This case provides an example of a patient with prompt diagnosis and appropriate chemotherapy in combination with surgery, which lead to excellent clinical outcomes. It is necessary to diagnose PCL as early as possible and it should be kept in mind in the antidiastole of cardiac tumors. At the moment, chemotherapy is an effective treatment and can improve the prognosis.

Declarations
Ethics approval and consent to participate This study was approved by the ethics committee of Nanjing Medical University.

Consent for publication
This manuscript and accompanying images were published with the patient's written informed consent.
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