An Autopsy Case of Mesenteric Panniculitis with Massive Pleural Effusions

BACKGROUND Mesenteric panniculitis (MP) is an idiopathic chronic inflammatory condition of the mesentery. The main symptoms include abdominal pain, abdominal distention, weight loss, fever, nausea, and vomiting. The patients also present with chylous ascites in 14% of the cases and chylous pleural effusion (CPE) in very rare occasions. Despite the previous view of excellent prognosis of MP, two recent papers reported several fatal cases. However, there are still only a few autopsy case reports that describe the macroscopic and histological details of MP cases. CASE REPORT The patient was an 81-year-old Japanese woman. She complained of edema of her lower legs and face, general fatigue, and dyspnea. She was overweight and had type 2 diabetes (T2D). Computerized tomography (CT) demonstrated massive bilateral pleural effusions, with mild pericardial effusion and mild ascites. There was no pulmonary, cardiac or hepatic condition to explain the effusions. However, MP was suspected based on her CT. She gradually deteriorated into respiratory failure. The autopsy revealed CPEs (left 1,300 mL, right 1,400 mL) and MP in the mesentery of the small intestine. Neither neoplasia nor inflammatory conditions other than MP were detected. CONCLUSIONS In rare occasions, patients with MP present with CPE or chylothorax. We thought that a possible mechanism of the CPEs was a diaphragmatic defect. We suspected that being overweight and T2D had an etiological relationship with MP in our patient's case. Adipose tissue of the mesentery is the main focus of MP. We believed that MP would be the best umbrella term of the many synonyms.