Metastasis of a pleomorphic adenoma

OBSERVATION: A 53-year-old man underwent a right parotidectomy in 1993 for a pleomorphic adenoma. The tumor relapsed locally, three years later, imposing a reoperation. The histology was unchanged. Two years later, the excision of a new local recurrence revealed a histological evolution with intravascular emboli, some cellular atypia and some mitoses. One year later, in a context of cephalgia and amaurosis, metastases were discovered on the calvarial skull. These were treated by radiotherapy. The patient died of a cerebral hemorrhage related to a history of familial autoimmune thrombocytopenia. DISCUSSION: Regional and systemic metastases of pleomorphic adenomas are exceptional. The local recurrence is characteristic of metastatic forms of pleomorphic adenomas; it occurs in 90% of the cases. No clinical or histological criterion allows distinguishing between recurrent metastatic forms and non-recurrent metastatic pleomorphic adenomas. The metastatic mechanism is not clearly elucidated yet. The best treatment for metastases of a pleomorphic adenoma is surgical excision. The recurrence after a complete surgical excision is rare and the prognosis excellent.