Pleomorphic adenoma of the accessory parotid gland misdiagnosed as glomus tumour

A 56-year-old man presented to the outpatient clinic of a tertiary referral center with a painless mass in the left midcheek region. The patient reported that the mass appeared two years earlier with gradually increasing size. He had visited a general surgeon 14 months earlier and an open biopsy of the neoplasm had been performed. In the medical report, the histopathological diagnosis of a glomus tumour was made. Past medical history was unremarkable. The mass was lying subcutaneously in the left cheek, was hard on palpation and non-adherent to the surrounding tissues. Ipsilateral facial nerve function was normal. Magnetic resonance imaging of the facial skull with gadolinium contrast revealed a well-defined, oval-shaped mass in the anterior border of the left masseter muscle (Figure 1). The tumour demonstrated high intensity signal in T2-weighted images and was markedly enhanced by contrast material. Maximum diameter of the neoplasm was 2.8 cm. Surgical removal of the tumour was decided. A fusiform incision that included the previous scar of the cheek was performed. Intraoperatively, the tumourwas found to originate from the accessory parotid gland. Thus, both were dissected free of the surrounding tissues and removed. The buccal and zygomatic branches of the facial nerve were recognized and preserved with the use of nerve monitoring (Figure 2). Stensen’s duct was also identified and secondary ducts running to the accessory gland were ligated. Histopathological examination of the tumour demonstrated pleomorphic adenoma of the accessory parotid gland, without any evidence of glomus tumour. Facial nerve function was normal postoperatively and the patient was discharged two days after surgery. No signs of recurrence have been noted 15 months postoperatively.