A Case of Hyalinizing Clear-cell Carcinoma With EWSR1-ATF1 Fusion Gene Arising From the Minor Salivary Gland of the Tongue.

BACKGROUND/AIM: Hyalinizing clear-cell carcinoma (HCCC) is a rare malignant tumor of the minor salivary glands characterized by nests of clear cells within a hyalinized stroma. Its diagnosis remains challenging due to its histological similarity to other neoplasms, and the recent recognition of distinct molecular features, such as Ewing sarcoma breakpoint region 1 (EWSR1)-activating transcription factor 1 (ATF1) fusion. This report describes a rare case of HCCC arising from the tongue with confirmed EWSR1-ATF1 fusion.

CASE REPORT: A 54-year-old man presented with a painless mass on the right lateral border of the tongue. Clinical examination revealed an elastic hard tumor measuring 18×15×8 mm. Biopsy under local anesthesia revealed a malignant clear-cell neoplasm. The lesion was completely excised under general anesthesia 2 weeks later. Histopathology showed nests of clear cells with polygonal nuclei in a hyalinized stroma. Immunohistochemistry demonstrated positivity for cytokeratin AE1/AE3, p63 protein and cytokeratin 7, and negativity for cytokeratin 20, α-smooth muscle actin, S-100 protein, vimentin, and cluster of differentiation 10. Periodic acid-Schiff staining was positive, with no diastase sensitivity. Fluorescence in situ hybridization revealed EWSR1 rearrangement, confirmed by reverse transcription-polymerase chain reaction as an EWSR1-ATF1 fusion. Perifocal stroma showed marked hyalinization. These findings support a diagnosis of HCCC with hyalinization. The patient remained disease-free 5 years after surgery.

CONCLUSION

This case highlights the diagnostic importance of integrating histopathology, immunoprofiling, and molecular analysis in patients with rare salivary gland tumors and underscores the favorable outcomes of complete surgical resection for HCCC of the tongue.