Pleomorphic Adenoma Metastasizing to Mandible and Scalp: Presentation of Two Unique Cases

Abstract

Abstract Metastasizing pleomorphic adenoma (MPA) is a rare salivary tumor that retains benign histopathology despite giving rise to metastases. The typical history of MPA is one of multiple local recurrences prior to developing metastasis. We present clinicoradiological and pathology data of two patients with MPA involving mandible and scalp and report their clinical course and surgical outcomes. Additionally, we review the literature on MPA affecting mandible and scalp subsites. One patient developed metastases 23 years after primary parotidectomy, without intervening recurrences. The other patient developed their first local recurrence 16 years after primary parotid resection. Later, developing multiple regional metastases to the scalp and mandible. Literature review revealed four prior reports of solitary mandibular MPA and five cases of MPA involving the scalp. MPA still represents a rare entity. It cannot be predicted as to which rare pleomorphic adenomas go on to develop metastases. Mandibular involvement might be misconstrued as local recurrence, but does represent a known site for “benign” metastases.