Docetaxel-Induced Serositis Mimicking Malignant Pleural Effusion

Pleural effusions are common in patients with cancer. Although their development may signal progressive malignant disease, drug-induced effusions are a rare and often overlooked cause of exudative pleural effusions. We describe a 50-year-old woman with recurrent granulosa cell tumor of the ovary who developed bilateral pleural and pericardial effusions after 10 cycles of docetaxel and bevacizumab. Imaging showed stable pelvic disease without thoracic metastases. Pleural fluid analysis revealed exudates with negative cytology and cultures. Pleuroscopy demonstrated normal pleura, and biopsies confirmed reactive mesothelial hyperplasia without malignancy. Bilateral indwelling pleural catheters were placed. After discontinuation of docetaxel, effusions resolved, and indwelling pleural catheters were removed. Docetaxel causes fluid retention, typically generalized, but isolated serositis is uncommon. In our case, the temporal association with docetaxel, absence of malignant pleural involvement, and resolution after drug cessation support a diagnosis of docetaxel-induced serositis. This highlights the importance of considering non-malignant etiologies in patients with cancer with new effusions. Further multidisciplinary evaluation in these cases is paramount. Drug-induced serositis should be considered in patients receiving docetaxel who develop pleural effusions, particularly when imaging shows stable disease and cytology is negative.