Intrathoracic Extrapulmonary Pleomorphic Liposarcoma: A Rare Presentation.

Liposarcoma (LPS) is a malignant mesenchymal neoplasm originating from adipocytes. LPS comprises several histological variants, among which pleomorphic liposarcoma (PL) constitutes a rare and highly aggressive subtype. PL is most commonly found in the extremities and presents primarily in individuals aged 50 and above. Primary thoracic presentations of PL are exceedingly rare, particularly in young adults, and are often associated with metastases to the lungs. This case reports a 28-year-old white male with no significant past medical history presenting with shortness of breath, left posterior thoracic pain, and a dry cough. Imaging revealed a large intrathoracic, extrapulmonary mass arising in the left pleura with compression of the heart and ipsilateral lung, resulting in atelectasis, but without evidence of chest wall or pulmonary invasion. Hemothorax, empyema, or pleural effusion were among the differentials initially suspected due to the location and density of the abnormality; however, drainage only yielded scant fluid. Thoracotomy for pleural decortication later revealed a solid mass with local pleural adherence. Histopathology of tissue biopsies confirmed a high-grade pleomorphic liposarcoma with extensive necrosis and pleomorphic lipoblasts. The patient was started on the AIM (adriamycin/doxorubicin, ifosfamide, mesna) regimen, and care was transferred for further oncologic management. Many features of this rare liposarcoma subtype were highly unusual, including the age of presentation, tumor location, lack of extensive lung invasion or metastasis, and absence of known genetic or environmental risk factors. Given the poor prognosis associated with PL, as well as its highly aggressive nature, treatment generally requires multimodal management that often challenges existing treatment frameworks. This is in part due to the relative deficit of literature regarding PL compared to other LPS subtypes. This case not only demonstrates an unlikely sarcoma presentation but also emphasizes the therapeutic limitations in managing pleomorphic liposarcoma and the necessity for further research into subtype-specific treatment strategies.