A Rare Case of Multilocular Mesothelial Inclusion Cysts of the Pericardium: Diagnosis, Treatment, Follow Up, with Comprehensive Review of the Literature

BACKGROUND: Multilocular mesothelial inclusion cysts-also known as benign multicystic mesothelioma (BMM)-are rare, typically arising in the peritoneal cavity. Pericardial involvement is extremely uncommon and can pose diagnostic and therapeutic challenges due to their recurrent and infiltrative nature. Accurate diagnosis and surgical strategy are critical for management and recurrence prevention. METHODS: We present the case of a 36-year-old woman with a prior history of malignant melanoma who developed recurrent multilocular cystic masses of the pericardium. Initial imaging with echocardiography, cardiac magnetic resonance (CMR), and computed tomography (CT) revealed multilocular pericardial cysts. Surgical resection was performed under cardiopulmonary bypass (CPB), but complete excision was limited due to epicardial infiltration. Histopathology confirmed a benign mesothelial origin. One year later, recurrence prompted a second surgical intervention with total pericardiectomy and Gore-Tex patch reconstruction. RESULTS: Postoperative recovery was uneventful in both instances. Follow-up imaging at 6 and 12 months demonstrated no significant recurrence. Histological analysis confirmed benign cysts lined with mesothelial cells, positive for calretinin and WT-1. This represents one of the first documented living cases of pericardial BMM managed with staged surgery and total pericardiectomy. CONCLUSIONS: Pericardial BMM is a rare, benign, but potentially recurrent lesion. In cases of extensive or recurrent disease, total pericardiectomy may offer definitive treatment. Multimodal imaging, histopathological evaluation, and personalized surgical planning are essential for effective management.