Reappraising hyalinizing clear cell carcinoma: A population-based study with molecular confirmation.

BACKGROUND: Hyalinizing clear cell carcinoma (HCCC) is a rare malignancy, characterized by EWSR1-ATF1 gene fusion, whose behavior is poorly understood, as it was for many years considered a diagnosis of exclusion. METHODS: All available salivary gland carcinomas (n = 594) from our institution were reviewed. Diagnosis of HCCC was confirmed by fluorescence in situ hybridization (FISH) for EWSR1. Literature review was performed. RESULTS: We found 15 patients with HCCCs (10 women, 5 men), 13 with EWSR1 rearrangement. Median age at diagnosis was 57 years (range, 31-87 years). Oral cavity (n = 9) and base of tongue (n = 4) were the most frequent primary sites. Combining our cases with those identified in literature review, the 10-year risk of local recurrence and locoregional nodal metastasis were 49% and 15%, respectively. CONCLUSION: Molecularly confirmed HCCC accounted for 2.5% of salivary gland malignancies at our institution. HCCCs are indolent tumors with a propensity for locoregional recurrence. © 2016 Wiley Periodicals, Inc. Head Neck 39: 503-511, 2017.