Iatrogenic epidermal inclusion cyst of the parapharyngeal space: unusual complication of ear surgery.

A 46-year-old man presented with a 12-month history of a slow-growing mass at the right anterior temporal and superior parotid region. He had a history of chronic otitis media and had undergone a modified radical mastoidectomy for cholesteatoma 5 years earlier. Physical examination revealed a sinus tract and diffuse soft tissue mass measuring 4 cm in diameter spread throughout the region of the right anterior temporal and superior parotid areas. Magnetic resonance imaging (MRI) showed three separate masses, including contrast material in the right superior parotid region and lateral skull base. The patient underwent a preauricular infratemporal approach. Six months later, a sinus tract recurred at the inferior border of the right zygomatic arch. MRI showed multiple masses in the right prestyloid parapharyngeal space, which were resected through a transparotid approach. The histopathologic diagnosis was an epidermal inclusion cyst (EIC). One year after the operation the patient was in good health and there was no sign of disease. EICs are rare tumors that are seen when epidermal elements are included in the dermis, which can follow trauma. EICs are unusual in the parapharyngeal space. Thus, until they become clinically observable, primary benign growths may not be recognized in this region. EICs must be considered in the differential diagnosis of growths in the parapharyngeal space, particularly among patients with a prior history of tympanomastoid surgery on the tumor side.