A Rare Presentation of Dedifferentiated Liposarcoma as Recurrent Pleural Effusion

Document Type

Conference Proceeding

Publication Date

5-2026

Publication Title

American Journal of Respiratory and Critical Care Medicine

Abstract

Introduction: Dedifferentiated liposarcoma (DDLPS) is de fined as the transition from well-differentiated liposarcoma/atypical lipomatous tumor to non-lipogenic sarcoma. DDLPS arises mostly in the retroperitoneum or deep soft tissue of upper extremities, involvement of the pleura is rare. Here, we present a case of DDLPS with primary involvement of the pleura. Case-Presentation: A 59-year-old male with prior history of hypertension was hospitalized for shortness of breath, thought to be secondary to hypertensive urgency and right pleural effusion. He was a never smoker, had an office job with no occupational exposure. He reported intentional weight loss with diet and exercise, he was an avid biker. He denied any fever. He underwent right thoracentesis with removal of 1550 ml of bloody fluid. Pleural fluid studies were consistent with exudative effusion with LDH level of 1168 U/L. Cytology was negative for malignancy, flow cytometry was positive for CD5+ monotypic B-cell (< 1%). The pleural fluid reaccumulated few weeks later. Repeat right thoracentesis with removal of 1750 ml of bloody fluid showed exudative effusion with LDH level of 1473 U/L. Repeat cytology was negative and concurrent flow cytometry again showed CD5+ monotypic B cells population (< 1%). CT Chest, Abdomen and Pelvis with contrast was done for further evaluation with findings of large multiloculated right loculated pleural effusion with associated pleural thickening. Patient subsequently underwent right video-assisted thoracoscopic surgery (VATS), drainage of effusion and pleural biopsy. The biopsy result revealed DDLPS and patient was referred to Oncology for further management. Discussion: Primary pleural involvement with DDLPS is rare, but has been reported. Our patient had exudative pleural effusion during thoracentesis with negative cytology on two occasions. Subsequent VATS with pleural biopsy showed a high-grade sarcomatoid neoplasm with immunostaining positive for MDM2 suggestive for DDLPS. Pathology was reviewed at a specialized center where fluorescence in situ hybridization (FISH) study were positive for MDM2 gene amplification with confirmation of DDLPS. Given that DDLPS is a rare tumor, referral to a Sarcoma Center with DDLPS expertise has been proposed for pathology review for confirmation of diagnosis and discussion at an experienced multidisciplinary tumor board for management. Surgery remains the only potentially curative option, but the feasibility of this differs based on anatomic location and the extent of the disease, highlighting the importance of multidisciplinary teams with disease-specific expertise for individualized management plans.

Volume

212

Issue

S1

First Page

S4491

Last Page

S4491

Comments

American Thoracic Society International Conference, May 15-20, 2026, Orlando, FL

DOI

10.1093/ajrccm/aamag162.6021

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