PCL is defined 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 . 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 nonspecific 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 definitive diagnosis is confirmed 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 infiltrating into the myocardium, with slight enhancement on contrast-enhanced scans. Meanwhile, coronary artery can be seen floating in the mass, which is a typical imaging manifestation of lymphoma called vascular floating sign [5, 6]. Nuclear medicine imaging (PET-CT) may assist in differentiate from other more common cardiac tumors, high uptake is the specific manifestation of PCL . Previous study has shown that SUV values of PCL patients was significantly higher than those of patients with other cardiac malignancies (such as metastatic tumors, sarcomas) and benign tumors .
The main treatment of PCL is the combination of surgery and chemotherapy . 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 . 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 . 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 flow 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 significantly 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 infiltration 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.