Granular cell tumor of the parotid gland presenting as a radiologically suspicious lesion: a case report

Abstract

Granular cell tumors (GCTs) are uncommon, typically benign neoplasms often linked to a Schwann cell origin, with parotid localization being exceptionally rare. This report details a rare case of a benign granular cell tumor (historically known as Abrikossoff’s tumor) originating in the parotid gland of a 35-year-old woman. The patient presented with a one-year history of a slowly enlarging, painless left pre-tragal mass. Imaging revealed a heterogeneous, poorly defined lesion with calcifications. The patient underwent a total parotidectomy with facial nerve preservation. Histopathological examination revealed tumor cells with abundant granular cytoplasm and absent cytonuclear atypia. Histological analysis confirmed a complete surgical excision with clear, negative margins (R0 resection). The diagnosis was confirmed by immunohistochemistry, which showed strong positivity for S100 protein, SOX10, and CD68, and negativity for DOG1 and mammaglobin. Although complete surgical excision with negative margins remains the primary treatment, long-term recurrence cannot be definitively excluded based on a 6-month follow-up period alone. This case underscores the importance of immunohistochemistry in diagnosing this rare entity and highlights the role of thorough preoperative evaluation to avoid potential overtreatment.