Granular cell tumor of the trunk of the facial nerve: A case report.

Rationale: Granular cell tumor (GCT) is a relatively uncommon, usually benign lesion that often presents as a solitary, painless cutaneous or submucosal nodule. GCTs of the head and neck are not uncommon; however, involvement of the trunk of the facial nerve is rare.

Patient Concerns: A 55-year-old woman presented a lesion at the posterior border of the left parotid gland. Doppler ultrasound revealed a hypoechoic mass and magnetic resonance imaging disclosed an irregularly shaped lesion with unsharp borders in the posterior aspect of the left parotid gland that was hyperintense on T2-weighted images and enhancing with contrast on T1-weighted images. The remainder of the parotid gland was normal.

Diagnosis: Following excision of the mass, diagnosis of a GCT was established and confirmed by immunohistochemistry.

Interventions: The patient underwent surgical excision of the lesion.

Outcomes: The patient is currently asymptomatic and without recurrence after 10 months follow-up.

Lessons: GCT involvement of the trunk of the facial nerve is rare. Immunohistochemical staining is helpful for its diagnosis.