3. Discussion
3.1 Clinical manifestations of PPM
The incidence of PPM is extremely low, with multiple occurrences in middle-aged men and an unknown etiology 3.PPM has no characteristic clinical manifestations, and the main symptoms are dyspnea, chest tightness, chest pain, cough, sputum, fever, and night sweats. The main signs of PPM include enlargement of the heart, distant heart sounds, pericardial percussion, and various signs of systemic congestion. PPM is often misdiagnosed as tuberculous pericarditis and constrictive pericarditis4. There was no history of asbestos exposure in this case. The patient had no obvious abnormalities in liver function 1 year ago, and long-term alcohol consumption led to alcoholic cirrhosis. Pericardial disease led to right heart failure, which accelerated the process of liver failure.
3.2 Imaging diagnosis of PPM
Echocardiography is the most frequently used method of evaluation of PPM and can identify the location and morphology of a tumor and assess the effect of the tumor on cardiac hemodynamics and determine the hypocardial function5. However, PPM lacks characteristic echocardiographic imaging changes, and its diagnosis is influenced by the experience and subjectivity of the ultrasound physician. Cardiac CT is better than echocardiography for observing pericardial changes, and enhanced scans can determine the condition of the large blood vessels of the heart. Studies have shown that low-density areas suddenly appear within the thickened pericardium, which may be associated with necrosis inside the tumor6. In the current case, cardiac CT showed marked pericardial diffuse thickening with nodular changes and decreased density of the heart chambers and large blood vessels, consistent with these studies. CMR can identify the surrounding soft tissue invasion and allows a reliable judgment on the nature of the pericardial tumor, the degree of myocardial infiltration, and the location7. PET-CT provides detailed molecular information about the function and metabolism of lesions, allowing for the early detection of pericardial tumors, and can determine benign and malignant nature and metastasis8. In summary, imaging data is conservative regarding the diagnosis of PPM, and generally prioritizes pericarditis in terms of imaging performance. Even with optimal cardiac CMR and PET-CT, there are often no characteristic changes and lesions are rarely considered as pericardial tumors, which is the main cause of preoperative misdiagnosis or missed diagnosis.
3.3 Pathological results and immunohistochemical analysis of PPM
Postoperative pathology combined with immunohistochemical analysis is the gold standard for diagnosis of PPM9.The anatomical typing of PPM includes diffuse and focal types, with diffuse types being more common. Histological classifications are epithelial, sarcoma, and bipolar, with epithelial being the most common10. Currently, combined immunohistochemistry showing negative expression of CKp (AE1/AE3), CK5/6, CK18/19, EMA, MC, wave protein (vimentin), calretinin, carcinoembryonic antigen (CEA), and thyroid transcription factor is recommended for PPM2,9-14.The immunohistochemical expression signature of PPM is mostly the permutation and combination of the above antibodies. This case also confirmed the results of the above pathological typing and immunohistochemical analysis, consistent with the diagnosis of PPM.
3.4 Treatment and prognosis of PPM
Surgery is the main treatment for primary cardiac malignancy, which not only removes tumor tissue and obtains material for the pathological diagnosis, but also relieves clinical symptoms caused by tumor blockage15. Because PPM is rare, a unified treatment specification has not been determined clinically. However, in PPM treatment, surgery is critical for solving pericardial thickening, adhesions, and restoring cardiac contractile function16. When the patient has life-threatening comorbidities, surgery can relieve pericardial compression, prolong survival time, and improve quality of life. In the current case, the surgical effect was remarkable, successfully relieving the pericardium from extensive thickening and adhesions. The patient was alive at follow-up at 3 months postoperatively. Postoperative combination of chemotherapy and radiation therapy may improve prognosis, but long-term efficacy remains poor. However, chemotherapy after cardiac malignancy resection should be beneficial 17. PPM treatment is trending towards a combination of surgery, radiotherapy, chemotherapy, and other comprehensive treatment measures.
PPM has extremely low incidence, atypical clinical manifestations, difficult early diagnosis, and poor prognosis. Nevertheless, clinicians should extend their understanding of the disease and strive to achieve early diagnosis, early intervention, and improve prognosis to enhance patient survival.
ACKNOWLEDGMENTS
We thank H. Nikki March, PhD, from Liwen Bianji (Edanz) (www.liwenbianji.cn/), for editing the English text of a draft of this manuscript.
CONFLICT OF INTERESTS
The authors declare no conflict of interest.
ETHICS AND LEGAL
IRB approval, clinical trial statement, and registration details are N/A. Informed consent was obtained from both the patient and their legal guardian for this case report.
AUTHOR CONTRIBUTIONS
Qiansu chen – Concept/Design, critical review of draft, case analysis, and interpretation.
Nailin Gong and Lude Liu have equal contributions to this article. – Case analysis and interpretation, report drafting, and revisions.