An Ectopic Pleomorphic Adenoma in the Superficial Subcutaneous Layer of the Preauricular Area

ABSTRACT

Pleomorphic adenoma is a benign tumor originated from the mature salivary tissue. Ectopic pleomorphic adenoma is defined as an unusual presentation of pleomphic adenoma in other sites except the major salivary gland and the minor salivary gland. Ectopic pleomorphic adenoma was found in the soft tissue of the neck, in the skin of the external auditory canal, in the subcutaneous layer of the nose, and in the lymph node of the mediastinum. Ectopic pleomphic adenoma could appear due to the metastasis, the neoplastic degeneration of the ectopic salivary tissue, or the implantation after the surgery of a salivary gland tumor. We present a case of pleomorphic adenoma found in the superficial subcutaneous layer above the superficial musculoaponeurotic system(SMAS) of the preauricular area. The patient had no history of the surgery of the salivary tumor and no specific physical finding. We discussed the previous cases of ectopic salivary tissues and ectopic pleomorphic adenomas. No case of the ectopic salivary tissue nor ectopic pleomorphic adenoma in the superficial subcutaneous layer of the preauricular area has been reported. This case could be a rare presentation of the ectopic pleomorphic adenoma from the ectopic salivary tissue arising from the division of the parotid gland in early embryonic period.