Primary tracheal hyalinizing clear cell carcinoma with EWSR1 rearrangement: A case report.

Hyalinizing clear cell carcinoma (HCCC) is a rare, low-grade epithelial tumor predominantly found in the salivary glands, with tracheal involvement being particularly uncommon. The present study details a case of primary tracheal HCCC and its clinical presentation, diagnostic challenges and the therapeutic approach used. A 34-year-old female patient presented with a 1-month history of intermittent dyspnea. Enhanced chest computed tomography demonstrated a hypervascular nodule occupying two-thirds of the tracheal lumen. Bronchoscopy results showed a mass with significant luminal obstruction. The initial biopsy revealed a poorly differentiated squamous cell carcinoma. The patient underwent surgical resection via a median sternotomy. Histopathology results showed a tumor characterized by trabecular, cord-like and nest-like arrangements within a hyalinized stroma. Immunohistochemistry was positive for carcinoembryonic antigen, cytokeratin (CK)7, CK5/6, pan-CK, epithelial membrane antigen, p40, p63 and p53, with a low Ki-67 index. Fluorescence hybridization analysis confirmed Ewing sarcoma RNA binding protein 1 gene rearrangement, leading to a definitive diagnosis of tracheal HCCC. Primary tracheal HCCC is a particularly rare neoplasm with distinct pathological features. The present case highlights the importance of considering HCCC in the differential diagnosis of tracheal tumors, and emphasizes the critical role of comprehensive histopathological and molecular analysis in achieving an accurate diagnosis and guiding treatment.