C43-42 From Pelvic to Pleura: An Unusual Diagnostic Journey to Gynecologic Malignancy

Abstract Introduction Pleural effusions secondary to gynecologic malignancies are uncommon presentations and may mask the underlying primary source. Low grade serous carcinoma (LGSC) of ovarian origin is a rare epithelial ovarian cancer subtype characterized by indolent growth but frequent presentation at advanced stages. Case report A 56 year female with no significant past medical history and without previous malignancy screening, presented with progressive shortness of breath and a productive cough. Initial imaging demonstrated a large right sided pleural effusion causing respiratory compromise. Diagnostic thoracentesis yielded exudative fluid positive for malignant cells consistent with secondary malignancy. Subsequent cross sectional imaging identified a complex adnexal mass without ascites. Image guided biopsy of the adnexal lesion revealed low grade serous adenocarcinoma, establishing the ovaries as the primary site. Discussion This case highlights an atypical initial manifestation of LGSC presenting with respiratory symptoms due to malignant pleural effusion without ascites. Identifying the primary tumor in patients with malignant pleural effusion is critical for prognosis and treatment planning. LGSC often presents with widespread peritoneal involvement but may also manifest with thoracic disease, underscoring the need for a thorough diagnostic evaluation. Conclusion Low-grade serous ovarian carcinoma, though uncommon, should be considered in the differential diagnosis of malignant pleural effusions in women without known malignancy. Early recognition facilitates appropriate oncologic referral and management. This abstract is funded by: none