Abstract
Introduction Schwannoma of the olfactory groove is an extremely rare tumor that can share a differential
diagnosis with meningioma or neuroblastoma.
Objectives The authors present a case of giant schwannoma involving the anterior cranial fossa
and ethmoid sinuses.
Case Report The patient presented with a 30-month history of left nasal obstruction, anosmia,
and sporadic ipsilateral bleeding. Computed tomography of the paranasal sinuses revealed
expansive lesion on the left nasal cavity extending to nasopharynx up to ethmoid and
sphenoid sinuses bilaterally with intraorbital and parasellar extension to the skull
base. Magnetic resonance imaging scan confirmed the expansive tumor without dural
penetration. Biopsy revealed no evidence of malignancy and probable neural cell. Bifrontal
craniotomy was performed combined with lateral rhinotomy (Weber-Ferguson approach),
and the lesion was totally removed. The tumor measured 8.0 × 4.3 × 3.7 cm and microscopically
appeared as a schwannoma composed of interwoven bundles of elongated cells (Antoni
A regions) mixed with less cellular regions (Antoni B). Immunohistochemical study
stained intensively for vimentin and S-100.
Conclusion Schwannomas of the olfactory groove are extremely rare, and the findings of origin
of this tumor is still uncertain but recent studies point most probably to the meningeal
branches of trigeminal nerve or anterior ethmoidal nerves.
Keywords
paranasal sinuses - skull base - neurilemmoma - olfactory nerve - head and neck neoplasms
- neoplasms - nerve tissue
