 British Journal of Neurosurgery, April 2014; 28(2): 281–283 © 2014 The Neurosurgical Foundation ISSN: 0268-8697 print / ISSN 1360-046X online DOI: 10.3109/02688697.2013.835377 Trigeminal schwannoma of the sphenoid sinus – report of a rare entity Sudheer Kumar Gundamaneni, Manish Singh, Venkatesh Shankar Madhugiri, Roopesh Kumar Vadivel Rathakrishnan & Gopalakrishnan Madhavan Sasidharan Department of Neurosurgery, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry, India Correspondence: Gopalakrishnan Madhavan Sasidharan, Department of Neurosurgery, Jawaharlal institute of post graduate medical education and research (JIPMER), Pondicherry 605006, India. Mobile: + 919345141431. Tel: + 0413–2297301 (Ofce). E-mail: gopalakrishnanms@yahoo.com Received for publication 2 March 2013; accepted 11 August 2013 Introduction Schwannomas are benign tumors which arise from the peripheral nerve sheath. Sinonasal schwannomas are uncommon. Sphenoid sinus schwannomas are even rarer and only a few cases have been reported in the literature. A high degree of suspicion is required to diagnose these uncommon benign tumors. Te surgical options for a sphenoid sinus schwannoma include endoscopic excision but decompression followed by a radiosurgery is also an acceptable option if there is extension of the tumor into the cavernous sinus or para cavernous sinus areas. Case report A 32-year-old man presented with several episodes of severe headache and right nasal blockade since the past 3 years. He had undergone septoplasty for deviated nasal septum but had no resolution of headache, although his nasal blockade was relieved. Later, a CT scan and MRI revealed a mass in the sphenoid sinus and nasopharynx. A biopsy and an attempt at excision were done by an ENT surgeon. Histopathology examination revealed that the lesion was a schwannoma. Post-biopsy MRI showed a large residual tumor. On exami- nation, olfaction was preserved. Contrast-enhanced CT scan showed an isodense lesion in the sphenoid sinus which enhanced homogenously. MRI demonstrated the sphenoid sinus lesion prolapsing into the nasopharynx. Te lesion was isointense on T1-weighted images (T1WI) and heterointense on T2-weighted images (T2WI) and showed non-uniform enhancement on gado- linium (Gd) contrast administration (Fig. 1). He under- went sublabial rhinoseptal trans-sphenoidal excision of the tumor. Te tumor was predominantly fbrous and very vascular. Tere was a small area of dural breach but there was no CSF leak. Post-operative MRI showed residual lesion for which a redo procedure via trans-ethmosphenoidal approach is planned. Discussion Schwannomas were frst described by Virchow in 1908. Schwannoma is a benign slow-growing tumor which arises from Schwann cells that are derived from the neuroecto- derm. About 25–45% of all schwannomas arise in the head and neck region. Only 4% of schwannomas of the head and neck region occur in the paranasal sinuses. Te most com- monly involved sinus is the nasal ethmoid sinus followed by the maxillary sinus. 1 Sphenoid sinus is a very rare location for these tumors. It was hypothesized that schwannomas occur more frequently in the nasal cavity and ethmoid sinus than in other paranasal sinuses because of relatively more abun- dant and complex nerve innervations. 2 Te origin of schwannomas arising from these sinuses are presumed to be from the peripheral nerve sheaths of the branches of the ophthalmic and maxillary divisions of the trigeminal nerves and their ganglion and lack of any other nerve divisions near these sinuses. 1 It is probable that the schwannomas arising from the sphenoid sinus are variants of trigeminal schwan- nomas except that they arise from peripheral extra-cranial nerve sheaths. It remains to be seen if these uncommon tumors can be studied in more detail in their earlier stages of development where the tumors are small and if with the developing radiological techniques like high-tesla MRI SHORT REPORT Abstract Schwannomas are common slow growing benign tumors. About 25–45% of all schwannomas arise in the head and neck region. Less than 4% of these tumors are found in sinonasal regions and usually afect nasal ethmoid. There are very few case reports of a schwannoma arising from the sphenoid sinus. We report a case of sphenoid sinus schwannoma treated by microscopic decompression and review the relevant literature. Keywords: paranasal; sinonasal; trigeminal sphenoid sinus schwannoma