Pleomorphic adenoma of the parotid gland 1985-2010: A Danish nationwide study of incidence, recurrence rate, and malignant transformation.

BACKGROUND

Pleomorphic adenoma is the most frequent salivary gland tumor and is known for its tendency to recur and for its ability to transform to carcinoma ex pleomorphic adenoma (Ca-ex-PA). Along with pleomorphic adenoma demographics, we present the first nationwide study with long-term follow-up on these topics.

METHODS

The Danish Pathology Data Bank was searched for parotid pleomorphic adenoma and Ca-ex-PA in the period 1985 to 2010 and all pathology descriptions were reviewed. Ca-ex-PA specimens were reviewed by a pathologist.

RESULTS

A total of 5.497 patients were identified and 2.86% had at least one recurrence. An incidence of 4.29/100,000/year was found. The rate of malignant transformation in recurrent pleomorphic adenoma was 3.3%.

CONCLUSION

We report an up-to-date assessment of the epidemiology of pleomorphic adenoma. We found an increasing incidence and low recurrence rate compared with previous studies. The risk of Ca-ex-PA for patients with recurrent pleomorphic adenoma was low compared to the literature. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1364-E1369, 2016.