Primary malignant pericardial mesothelioma with difficult antemortem diagnosis: A case report

BACKGROUND: Primary malignant pericardial mesothelioma (PMPM) is an extremely rare malignant tumor, and it is difficult to diagnose definitively before death. We present a case in which PMPM was diagnosed at autopsy. We consider this case to be highly suggestive and report it here. CASE SUMMARY: A 78-year-old male presented with transient loss of consciousness and falls. The transient loss of consciousness was considered to result from complications of diastolic dysfunction due to pericardial disease, fever with dehydration, and paroxysmal atrial fibrillation. Ultrasound cardiography (UCG) and computed tomography showed cardiac enlargement and high-density pericardial effusion. We considered pericardial disease to be the main pathogenesis of this case. Cardiac magnetic resonance imaging and gadolinium contrast-enhanced T1-weighted images showed thick staining inside and outside the pericardium. Pericardial biopsy was considered to establish a definitive diagnosis, but the patient and his family refused further treatment and examinations, and the patient was followed conservatively. We noticed a thickening of the pericardium and massive changes in the pericardium on UCG over time. We performed an autopsy 60 h after the patient died of pneumonia. Giemsa staining of the autopsy tissue showed an epithelial-like arrangement in the pericardial tumor, and immunostaining showed positive and negative factors for the diagnosis of PMPM. Based on these findings, the final diagnosis of PMPM was made. CONCLUSION: PMPM has a poor prognosis, and early diagnosis and treatment are important. The temporal echocardiographic findings may provide a clue for the diagnosis of PMPM.