Calcified Pleural Dissemination and Malignant Pleural Effusion in Dedifferentiated Chondrosarcoma: A Case Report with an Institutional Review

This is the authors' abstract. We don't add key points for this paper.

Dedifferentiated chondrosarcoma (DDCS) rarely presents with pleural dissemination or malignant pleural effusion. A 62-year-old man developed massive left pleural effusion with diffuse calcified pleural thickening and nodular lesions. Pleural fluid cell block immunohistochemistry showed cytokeratin AE1/AE3 negativity and SATB2 positivity, suggesting a mesenchymal tumor. Pelvic imaging suggested a chondroid matrix, while a biopsy revealed a high-grade osteoid-producing component with an IDH1 p.R132C mutation. Integrated pleural fluid, imaging, histopathological, and molecular findings supported the diagnosis of DDCS. An institutional review provided descriptive context but could not estimate the DDCS-specific frequency. This case highlights an uncommon pleural presentation and the adjunctive value of a pleural fluid cell block analysis.