A Large Facial Nerve Schwannoma Presenting as a Swelling in Parotid Region-A Rare Case Report

Abstract

Extratemporal facial nerve schwannomas are rare entity. Pre-operative assessment is mostly inconclusive with differential diagnosis of parotid tumors. We hereby report a case of 28 years female who presented with painless swelling in right parotid region with normal facial nerve function. Ultrasonography was suggestive well circumscribed and homogenous mass arising from the deep lobe of parotid gland. The Fine-needle aspiration cytology came out to be inconclusive. For further characterization of the tumor contrast enhanced MR imaging was performed. The MR imaging revealed well-defined cystic, heterogeneous, pear-shaped mass lesion situated near the stylomastoid foramen. Post operatively the mass came out to be schwannoma on histopathological examination.

Keywords: Extratemporal; Facial nerve; Histopathological examination; Schwannoma.

Fig. 1

Preoperative House-Brackmann Grade 1 facial nerve function

Fig. 2

CE-MRI of the neck revealing a tumour well-defined cystic, heterogeneous, pear-shaped mass lesion arising from the facial canal on right side extending extracranial from the stylomastoid and lying in the right parotid region in close proximity to its deep lobe

Fig. 3

Diagram depicting site of lesion

Fig. 4

Thin sheath of nerve fibers covering the tumor

Fig. 5

Well encapsulated with normal adjoining parotid tissue and was removed in toto

Fig. 6

Histology Antoni A (×100) Antoni B (×100)

Fig. 7

Immunohistochemistry S-100 POSITIVE