Clinical manifestations of recurrent parotid pleomorphic adenoma

Abstract

Objectives: This study was undertaken to confirm the clinical characteristics of recurrent pleomorphic adenoma (RPA), and to identify those factors that affect the development of malignant transformation (MT) from RPA.

Methods: The medical records of 270 patients, who were operated upon for parotid PA, were retrospectively reviewed. The pathologic specimens of a selected series of 23 patients were reviewed for histologic subtype and microscopic multi-nodularity.

Results: Mean age of initial operation in RPA without MT (RPA(-MT)) group was significantly lower than that of primary PA group. Mean age of the revision operation in RPA with MT (RPA(+MT)) group was significantly greater than that of RPA(-MT) group. Mean interval from operation to recurrence shortened after each revision operation. The risk of MT and additional recurrence increased significantly with recurrence. In RPA(-MT) group tumor recurrence occurred in 21.4% of patients despite a clear resection margin.

Conclusion: The risk factors for MT may be an age of over 45 yr and multiple recurrences. However, younger patients are more at risk of recurrence. A clear resection margin cannot guarantee a cure in RPA, and it seems that parotid pleomorphic adenomas slowly gain malignant characteristics after repeated recurrences.

Keywords: Parotid glancl; Pleomorphic adenoma; Recurrence; Risk factor.

Fig. 1

Progressive changes in clinical manifestations after multiple recurrences. Duration between revision operations and subsequent recurrences tended to shorten as the number of previous revisions increased (P=0.06). The percentage of patients with a malignant tumor at revision surgery was higher than at initial operation (P=0.04). The general trend toward an increased risk of further recurrence after repeated surgery was significant (P<0.01), despite our finding of a lower risk at the third than at the second operation.