Primary pulmonary myxoid sarcoma: A case report

Pulmonary myxoid sarcoma is an rare and poorly understood malignant neoplasm that primarily arises within the pulmonary tissue. Characterized by its distinctive histological features of myxoid stroma and spindle-shaped cells, this neoplasm poses significant diagnostic and therapeutic challenges due to its rarity and the non-specific nature of its clinical presentation. Current knowledge regarding the pathogenesis, optimal therapeutic strategies and prognostic factors for pulmonary myxoid sarcoma remains limited, primarily due to the scarcity of reported cases and comprehensive studies. The present study reports a case of pulmonary myxoid sarcoma. A 41-year-old male was admitted to the Jeonbuk National University Hospital due to a pulmonary mass in the left lower lobe discovered during a routine health check-up. A CT scan performed at our hospital revealed a nodule ~1 cm in size in the mediobasal segment of the left lower lobe, with relatively well-defined margins and significant enhancement. A wedge resection was performed for diagnosis and treatment, and frozen section examination showed a high likelihood of pleomorphic adenoma. The histological findings of the permanent section examination revealed an abundant myxoid matrix with embedded spindle, stellate and rounded/epithelioid cells arranged in a reticular pattern. The tumor cells exhibited mild to moderate cellular atypia, with rare mitotic figures. Immunohistochemistry showed positive staining for vimentin and negative findings for myoepithelial cell markers such as calponin, high-molecular weight cytokeratin and p63. The presence of the EWSR1-CREB1 fusion was confirmed through fluorescence in situ hybridization and reverse transcription-PCR analyses. Based on these findings, the nodule was diagnosed as pulmonary myxoid sarcoma.