Recurrent pleomorphic adenoma of the parotid gland: A population-based study with emphasis on re-recurrence and malignant transformation.

BACKGROUND: This study aimed to analyze the prognostic determinants for re-recurrence and malignant transformation of parotid recurrent pleomorphic adenoma (RPA). METHODS: Between January 2011 and December 2020, all the cases of RPA of the parotid gland at our single institution were reviewed. RESULTS: A total of 168 patients were included in this study, with a median age of 41.5 years, and 20 (11.9%) patients developed re-recurrence during follow-up. It has been evidenced that recurrence times (single or multiple) was an independent prognostic factor for recurrence-free survival (p = 0.0264). A total of 26 (15.48%) patients experienced malignant transformation of parotid RPA, and older age (>45 year old), male sex, and higher clinical tumor staging (T3-T4) were significantly associated with malignant transformation of parotid RPA. CONCLUSIONS: Recurrence times was an independent prognostic factor for re-recurrence of parotid RPA, and older male with high T-stage may more easily develop malignant transformation.