Pleomorphic Adenoma of the Submandibular Gland with Skull Metastasis: A Case Report.

Metastasizing pleomorphic adenoma is a rare entity that has the propensity for distant metastasis despite being histologically benign. We report the case of a 56-year-old woman with a long-standing right upper neck swelling and a recent-onset swelling over the left side of the scalp. Clinical workup did not reveal any other tumor deposits in the body. Complete excision of the right submandibular gland and the scalp swelling was performed. The case was diagnosed as metastasizing pleomorphic adenoma. The exact cause of the malignant manifestation of this histologically benign entity is unclear. The time of appearance of a metastatic deposit is highly variable and is usually preceded by a local recurrence. Further research on the malignant behavior of this entity is warranted.