Prognostic factors for secondary recurrence of pleomorphic adenoma: a 20-year, retrospective study.

Purpose: To evaluate the results of treatment of parotid pleomorphic adenoma, and the risk factors for secondary recurrence.
Materials and Methods: Single-centre, retrospective study of 32 patients with pleomorphic adenoma recurrence managed between 1988 and 2008.
Results: The mean age at diagnosis of primary pleomorphic adenoma recurrence was 43.4 years. Twenty-eight per cent of patients had secondary recurrence; 32 per cent had undergone two or more surgical resections and external adjuvant radiotherapy. An age of less than 25 years was significantly associated with an earlier primary recurrence (p = 0.008). The most significant histopathological risk factor for secondary recurrence was the presence of a multifocal tumour (p = 0.019). Other histopathological criteria (i.e. cellularity and capsule rupture) were not significant. Radiotherapy was not associated with a decrease in recurrence. Nine per cent of patients progressed to malignancy. The main surgical complication was definitive facial palsy (14 per cent).
Conclusion: Pleomorphic adenoma recurrence requires surgery, with greatly increased risk to the facial nerve. Resection with clear surgical margins is required, especially in young patients with multifocal tumours. Radiotherapy may delay second recurrence in cases of multifocal tumour.