Endoscopic Endonasal Resection of a Schwannoma of the Anterior Cranial Fossa

Abstract

A 75-year-old male with a 2-year history of anosmia, nasal obstruction, and headaches visited at the Otolaryngology Unit of Villa Sofia-Cervello Hospital in January 2017. In the beginning, anosmia was the only symptom, but over time, the patient reported difficulty in breathing through the nose and frequent headaches. Endoscopic examination showed a large mass involving the right nasal cavity (Figure 1A). Computed tomography (CT) scan was performed at the Radiological Unit, showing a lesion arising from the right anterior olfactory cleft extending throughout the whole right nasal fossa and a reactive ethmoid–maxillary sinusitis (Figure 2A). An endoscopic preoperative biopsy, performed under local anesthesia, lead to the diagnosis of Schwannoma of the olfactory nerve. Then the patient underwent transnasal endoscopic removal of the mass. Firstly, the surgeon debulked the neoformation starting from the right nasal fossa; afterward, right middle turbinectomy and progressive cauterization up to the olfactory fissure were performed (Figure 1B and C). The Schwannoma was completely removed, including the dural component, determining cerebrospinal fluid (CSF) leak, closed by a triple-layer fascia lata interposition (intracranial intradural, intracranial extradural, extracranial) and Autologous Fibrin Glue (AFG), placed in drops to fix the graft. The closure was completed with a free flap of the nasal mucosa with adipose tissue and more AFG sprayed over the closure region. The patient was then transferred to the intensive care unit and remained in anti-Trendelenburg position for 48 hours. Afterward, a nasal endoscopy showed no more evidence of CSF leaks. No complications (local toxicity, allergy reactions, infections) were observed. After 30 days, the patient underwent follow-up magnetic resonance imaging (MRI; Figure 2B and C) and endoscopy. Definitive histological examination showed a spindle cell proliferation with hemorrhagic and pseudocystic areas (Figure 3A). Furthermore, the diagnosis of Schwannoma with low expression of Ki-67 (Figure 3B), S100 (Figure 3), and Leu7/ CD57 positive with degenerative changes was confirmed by immunohistochemical analysis.