Metastasizing pleomorphic adenoma: a report of three cases.

Three cases of metastasizing pleomorphic adenoma are described. All three had a history of incomplete surgery of the primary tumour and several surgical procedures for local recurrences before systemic metastases became apparent. The histology of the primary tumour, recurrences and metastases were typical of pleomorphic adenoma. In view of the lack of information in the literature, it is concluded that inadequate surgical procedures, such as incomplete surgery or enucleation, leading to multiple recurrences, appear to be a prerequisite for the development of systemic disease.