title: Isolated schwannoma of the olfactory groove: a case report.
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.
authors.affiliation: Division of Skull Base Surgery, Department of Otolaryngology-Head and Neck Surgery, Universidade Federal de São Paulo, São Paulo/SP, Brazil.
authors.forename: Luiz Augusto
authors.initials: LA
authors.lastname: Nascimento
authors.affiliation: Division of Skull Base Surgery, Department of Otolaryngology-Head and Neck Surgery, Universidade Federal de São Paulo, São Paulo/SP, Brazil.
authors.forename: Flávio Aurélio Parente
authors.initials: FA
authors.lastname: Settanni
authors.affiliation: Department of Head and Neck Surgery, Instituto do Cancêr Arnaldo Vieira de Carvalho, São Paulo/SP, Brazil.
authors.forename: José Franscisco de Góis
authors.initials: JF
authors.lastname: Filho
authors.affiliation: Department of Oncology, Universidade Federal de São Paulo, São Paulo/SP, Brazil.
authors.forename: Isabela Naria Dias
authors.initials: IN
authors.lastname: Sanchez
authors.affiliation: Department of Head and Neck Surgery, Universidade de Brasília, Brasília/DF, Brazil.
authors.forename: Bruna Barros
authors.initials: BB
authors.lastname: Cavalcante
authors.affiliation: Department of Pathology, Universidade Federal de São Paulo, São Paulo/SP, Brazil.
authors.forename: João Noberto
authors.initials: JN
authors.lastname: Stávale
keywords: head and neck neoplasms; neoplasms; nerve tissue; neurilemmoma; olfactory nerve; paranasal sinuses; skull base