Pseudo-Meigs'syndrome mimicking malignant pleural mesothelioma: a case report and diagnostic pitfall analysis

To investigate the clinical characteristics, misdiagnosis causes, and preventive strategies of pseudo-Meigs' syndrome, and to improve clinicians' awareness of pelvic tumors presenting with pleural effusion and ascites.

A 45-year-old woman presented with a 2-month history of dyspnea and a large right-sided pleural effusion with markedly elevated CYFRA 21-1 (>500 ng/mL). Thoracoscopic pleural biopsy showed atypical cells with positive Calretinin, leading to a pathology report of "suspicious for mesothelioma." The patient was diagnosed with malignant pleural mesothelioma and received two cycles of pemetrexed plus carboplatin chemotherapy. When symptoms did not improve and ascites developed, pelvic CT revealed a 7.0 × 5.5 cm ovarian mass.

Postoperative pathology confirmed bilateral ovarian borderline serous cystadenoma with focal low-grade serous carcinoma-pseudo-Meigs' syndrome. After tumor resection, the pleural effusion and ascites resolved completely, and the patient remained disease-free at 4-year follow-up.

Pseudo-Meigs' syndrome can closely mimic malignant pleural mesothelioma. For any woman with unexplained pleural effusion, pelvic imaging should be performed before invasive thoracic procedures to avoid catastrophic misdiagnosis.