Hyalinizing clear cell carcinoma of salivary gland origin in the head and neck: clinical and histopathological analysis.

Hyalinizing clear cell carcinoma (HCCC) is an extremely rare neoplasm of salivary gland origin with a low-grade indolent nature. It is difficult to distinguish from other malignant salivary gland tumours. Clinical outcomes following surgery are generally reported as good. The aim of this study was to further determine the features of HCCC. This study was approved by Medical ethics review of affiliated hospital of jiangsu university. Fourteen new cases of HCCC are reported. The clinical and histopathological data of these 14 cases were analysed alongside those of 141 cases identified in a systematic review of the literature (up to 2016). Demographic data, histopathological findings, clinical presentation, primary treatment, and outcomes were extracted. Histologically, HCCC tumour cells had a clear cell morphology with hyalinized stroma. Immunohistochemical results were positive for cytokeratins and EMA, but negative for SMA, S100, vimentin, and calponin. Twelve of the 14 patients showed EWSR1 translocation. Local nodal metastasis on presentation was present in 17.3% and the overall recurrence rate was 17.7% in the total population (N=155), compared with 35.7% and 21.4%, respectively, in the new cases alone. Focal necrosis and local metastasis were identified as possibly associated with recurrence. The overall prognosis was good: only 3.8% of patients died of the disease. HCCC is less indolent than was previously thought, but overall the prognosis is good. Risk factors for recurrence may include focal necrosis and local metastasis at presentation. The best treatment for patients with HCCC is wide local excision combined with regional lymph node dissection.