| Nasal Schwannoma A schwannoma is a tumor arising from the Schwann cells. It was first described as a distinct pathological entity by Vérocay in 1908. He was actually a pathologist from Uruguay. In Italy, in 1920, Antoni described two distinct histological patterns for the lesion. The first description of a schwannoma in the nasal cavity dates back to 1926; this was in Germany. The term "schwannoma" was proposed by del Río Ortega in 1942, as well as several other authors during that period of time. Previously used terms for schwannoma—there are a lot of them and it makes the medical searches difficult—but neuronoma, perineural fibroblastoma, peripheral glioma, and schwannoglioma are just a few to name. These have fallen out of favor because they really indicate that the lesions contain all elements of the nerve, when the schwannoma really comes from the Schwann cell itself. Schwannomas may develop virtually anywhere in the body. They arise from the myelin sheath to peripheral motor, sensory, sympathetic, or cranial nerves. It is the peripheral nervous system that we will be concerned with today, really the cranial nerves of the sinonasal area. But again, they can come from either somatic or autonomic functional classes of other peripheral nerves. Schwann cells are neuroectodermal cells which sheath the axons and form the perineurium of these peripheral nerves. Here is an H&E slide showing the Schwann cell, as well as an electron micrograph showing the Schwann cell, and here is the peripheral sheath of myelin with the axoplasm of the axon. The central nervous system in contrast to the peripheral nervous system is myelinated by the glia cell. Again, today we are going to be concentrating on the peripheral nerves; and this is a picture depicting the axon of the peripheral nerve as well as the nucleus and the Schwann cell itself. The olfactory and optic nerves are essentially extensions of the central nervous system. They are encased by glia cells. They lack the sheath that contains Schwann cells, and they do not give rise to schwannomas in the head and neck region. Structures of origin in this region include sympathetic nerves to the sinonasal blood vessels. Here are sympathetic nerves to the sinonasal mucus glands and sensory nerves to the sinonasal mucosa. The schwannomas arise from either the ophthalmic or the maxillary branches of the trigeminal nerve and both sympathetic fibers from the cephalic ganglion and/or parasympathetic fibers from the sphenopalatine ganglion are also found in the nasal mucosa. Here is a picture depicting the nasal palatine and greater palatine nerve. Between 25% and 45% of all schwannomas have been observed in the head and neck region. This is the highest incidence when compared to anywhere else in the body. The vestibular nerve is the most frequent site of origin, but the scalp, face, oral cavity, tongue, soft palate, pharynx, larynx, trachea, parotid, middle ear, internal and external auditory meatus, and the neck are also less frequently involved but still sites of origin. Only 4% of these schwannomas, though, originate in the sinonasal tract. It is very rare. Higo in Japan in 1993 reviewed the world literature and collected 160 cases of schwannoma of the paranasal and nasal sinuses. He found an age distribution between 6 years and 78 years, with most patients presenting between their second and fifth decades of life. There was no prevalence for race or sex. The ethmoid and really the nasoethmoidal region was most frequently involved, followed by the maxillary sinus, the nasal cavity, and then the sphenoid sinus. There were no cases arising solely from the frontal sinuses, and the lesions were almost always solitary. This is a table from that report. Again, if you take the ethmoid and the nasoethmoidal region, that is the most frequently involved, followed by the maxillary sinuses and the nasal cavity and the sphenoid sinuses. There were four reports of frontal sinus involvement, but they were always in conjunction with the ethmoid sinuses, and they were thus excluded from the total. Nasal and paranasal schwannomas are accompanied by signs or symptoms, and they usually relate to the anatomic side of involvement of the lesion, the nerve of origin, and compression of adjacent structures. The most common symptoms your patients will have will be unilateral nasal obstruction, epistaxis, mucopurulent rhinorrhea, anosmia, or pain. Less frequently observed are exophthalmus, facial swelling, and epiphora, and these are really when the lesions are more advanced. Extensions to the sphenoid sinus can lead to diplopia with cranial nerve III, IV, or VI palsy; deep retroorbital pain; occipital, frontal or bitemporal headaches; or hypopituitarism in very advanced cases. Nasal schwannomas usually take a benign course, but intracranial extension has also been reported in the literature. The schwannomas commonly display a polypoid appearance without any distinctive features; and the differential diagnosis, therefore, is very broad and includes a spectrum of lesions ranging from angiomas and polyps to malignant tumors, such as melanoma or olfactory neuroblastoma. This is basically a chart of a unilateral nasal mass showing the broad range of differential diagnoses, and the schwannoma is on that list. CT scan clearly depicts the relationship of the lesions to the surrounding bony structures. The lesions usually have a mottled appearance with peripheral intensification on contrast-enhanced CT scans. Heterogenous appearance is sometimes seen as related to the areas of increased vascularity, with adjacent non-enhancing or cystic necrotic degeneration. This is our actual patient again. You can see the capsule of the lesion, and it does not show up very well here, but there are some heterogenous changes in the center of the lesion and calcification. Magnetic resonance imaging is superior to CAT scan in differentiating the tumor from inflammatory changes. It is also very useful in evaluating intracranial extension. Sinonasal schwannomas usually have an intermediate intensity on T1-weighted images and the T2-weighted signal varies from intermediate to high, depending on the cellularity of the lesion and the cystic characteristics of the lesion. But you typically, like any other schwannoma, get a more uniform enhancement pattern after gadolinium administration. This is again our patient, and this is pre-contrast—and you can see the mottling of the lesion and the heterogenous appearance—and this is post contrast, and you can see that it is a lot cleaner and enhancing more evenly across the field. Macroscopically, once removed the schwannomas appear as gelatinous or cystic long encapsulated masses. They are oval, round, or fusiform in shape. The enlargement of the lesion can lead to areas of cystic degeneration as the tumor outgrows its blood supply. Other aggressive changes found are necrosis, lipidization, and formation of angiomatous clusters of blood vessels with focal thrombosis. The histopathology shows a biphasic pattern of Antoni A and Antoni B areas. The Antoni A areas are of compact cells with twisted nuclei and occasionally intranuclear vacuoles. Cells are arranged in short bundles or interlacing fascicles. There is nuclear palisading and whirling of the cells, and the focal site where the nuclear palisades come together and bundle and parallel fibers are termed Verocay bodies. The Antoni B areas are the degenerative areas composed of spindle-cell shapes running in a haphazard manner. They are more loosely arranged in a fibrillar myxoid listroma, and the vessels are more prominent and dilated with hyalinized walls. The entire tumor may be composed of either area. They are commonly intermixed, and it is really of academic interest. The diagnosis will come with either an Antoni A or Antoni B presentation. These are two slides showing the Antoni A and B areas. This is a Verocay body here with the nuclear palisading of the spindle cells lining up in a parallel fashion. This whole area would be the Verocay body right here. And this is the Antoni B area. It shows the hyalinized blood vessels with focal thrombosis and loose stroma. Immunohistochemical staining is very important for the pathologist in determining these lesions. They do stain for S100, and benign schwannomas show a strong and diffuse immunoreactivity for the S100 protein. It is actually a calcium channel messenger thought to be of neuroectoderm origin. It is a neural crest marker. On your differential you are going to have a lot of other unilateral nasal lesions that can be a schwannoma or other things; but negative for S100 will be the juvenile angiofibromas, solitary fibrous tumors, hemangiopericytomas, or fibrous sarcomas. When the pathologist sees focal S100 positivity, it is either usually a malignant a nerve sheath tumor, which we will talk about in a little bit, or leiomyosarcomas. Variable S100 positivity is typically a meningioma. So, benign tumors of the nerve sheath are either schwannoma or neurofibroma. The two neural neoplasms share a common cytogenic origin, the Schwann cell, but differ both clinically and pathologically. The schwannoma is usually solitary and tender and has degenerative changes. The neurofibroma is usually multiple and nontender. It is associated with von Recklinghausen's disease, which is neurofibromatosis type I, and is less commonly present with aggressive changes. Neurofibromatosis type I, also known as von Recklinghausen's disease, is an autosomal dominant disorder due to mutation in the NF1 gene on chromosome 17. The incidence is 1:3,000 births. The pathology usually shows multiple plexiform nerve fibromas, and these are just some of the clinical features that you will see: café-au-lait spots, osteolysis, or cutaneous or cranial nerve neurofibromas. Here is just a picture of some cutaneous neurofibromas, and this is von Recklinghausen. Neurofibromatosis Type II really is not in our differential, but I thought it important to mention just briefly today. It is the central form of neurofibromatosis. It is autosomal dominant with a mutation of chromosome 22. The diagnosis is brought on by bilateral acoustic neuromas as seen in this MRI, as well as a first degree relative with unilateral acoustic neuroma, neurofibroma, meningioma, glioma, or juvenile subcapsular lenticular opacities. Café-au-lait spots in the cutaneous neurofibromas are less common. Neurofibromas are not encapsulated and are formed by a combination of all elements of the peripheral nerve. This includes the axons, the Schwann cells, the fibroblasts, and the perineural cells. That is depicted in this picture here; and that is juxtaposed to our schwannoma, which is really encapsulated and only containing part of the Schwann cell itself. Neurofibromas often contain mass cells and are composed of streams of spindle cells with serpentine nuclei. And again, here is our nasal schwannoma with the spindle cells in a palisading faction and the cutaneous nerve fibroma with the streaming of the spindle cells. When evaluating these patients, history and physical, of course, is very important and nasal endoscopy is imperative. You need to approach the mass as any other unilateral nasal mass, and imaging is necessary to evaluate the nature of the lesion and for detecting intracranial or skull-base involvement. Our patient in the case presentation came in with both CT and MRI. Angiography may be necessary to rule out an angiofibroma, and a transnasal biopsy is valuable for confirming the diagnosis and surgical planning. The treatment of choice for nasal and paranasal schwannomas, like any other schwannoma, is wide surgical excision. The approach must allow adequate exposure, and it is determined according to location and extent of the lesion. It can involve various combinations of techniques, including lateral rhinotomy, external ethmoidectomy, Caldwell-Luc approach, midface degloving, and/or endonasal endoscopic resection. Radiotherapy is not advocated for controlling benign disease, although it is advocated for malignant degeneration of the schwannoma; and recurrence is very rare after total excision. Malignant transformation of a nasal schwannoma is an exceedingly rare event; and in an extensive review of 430,00 cases of nonepithelial tumors of the nasal cavity and paranasal sinuses as well as the nasopharynx, Pearson found only four cases of malignant schwannoma. These malignant schwannomas typically occurred throughout the same age range as nasal schwannnomas, between the second and fifth decade and are usually more aggressive with invasion of surrounding tissue structures. They most frequently present in the head and neck as an expanding mass of one or more of the lower cranial nerves, as well as from the proximal aspect of the brachioplexus. Most malignant tumors are anaplastic neurofibromas, again in this region. But schwannomas can and very rarely undergo anaplastic transformation. Also of note, and mentioned along with malignant schwannomas, is the malignant triton tumor which contains both neurofibromatosis elements as well as rhabdomyosarcomatous components; and we will look at the histologist side of that as well. When looking at malignant schwannoma histopathology, the fascicular non-palisading growth pattern is usually evident as contrasted to the benign disease. There are hyperchromatic spindle cells with buccal nuclei and increased mycotic activity, and there is usually focal S100 positivity. The treatment for these lesions is wide local excision, but postop radiotherapy and chemotherapy are advocated by some authors. Again, it is very rare to have a benign disease and even rarer to have malignant degeneration, but there are case reports where the lesion was partially removed and the patient received postop radiotherapy and chemotherapy and did very well. It is also important to note that there is an increased risk of malignant degeneration with neurofibromatosis, and this is much higher with reports of anywhere between 8 to 15% of the cases in the literature. And these are just two histology slides, first showing a malignant schwannoma. You can see elements very similar to the benign disease, but you lose the palisading effect of the spindle cells; and this is a malignant triton tumor showing both spindle cells as well as sarcomatoid elements. So, in summary, the schwannoma is a benign tumor that rarely involves the nose and paranasal sinuses. There is no predilection for sex, age, or race. The ethmoid sinus, and really the nasoethmoid region, is most frequently involved. The most common complaints of schwannomas of the nasal cavity are nasal obstruction and epistaxis, very nonspecific. The nasal and paranasal schwannoma commonly display a polypoid appearance without any distinctive clinical features. CT and MRI are not able to make the diagnosis by themselves, but they are useful for determining the location and extension of the tumor, and they will map the approach for surgical excision. The schwannomas tend to be solitary and are usually well circumscribed, and they do have the distinct histopathological characteristics of Antoni A and Antoni B areas. They vary both clinically and pathologically from neurofibromas. Only surgical resection is curative for these lesions, and the benign forms tend to be radio-resistant. The approach for the resection must be chosen according to the location and extension of the tumor, and the nerve of origin is not typically identified. Recurrence is rare. Case Presentation: A.L. is a 37 year-old Arican-American female referred from her primary care physician for evaluation of a left sided nasal obstruction. She first noted the obstruction one year ago which has progressively become worse over time. She reports one episode of sinusitis six months ago which resolved with oral antibiotics. No other head and neck complaints were reported. Her left sided nasal obstruction persisted and further outside work-up with CT scan and MRI was completed. These studies revealed a 4x4 cm mass in the left nasal cavity extending into the left nasopharynx and maxillary sinus. Evaluation by an outside otolaryngologist resulted in an initial diagnosis of nasal polyp. Concern for a possible neoplastic process resulted in referral to the Baylor Otolaryngology service for evaluation and treatment. On exam, the right nasal passage was patent. The left nasal passage was totally obstructed. At the posterior third, a large, firm, polypoid soft tissue mass was noted extending into the nasopharynx. The left middle meatus was blocked. The remainder of the head and neck exam was unremarkable. Biopsy of the mass with local anesthesia was performed with Takahashi forceps. Bleeding was controlled. Pathology revealed respiratory mucosa with a subjacent spindle cell process. Spindle cells were eosinophilic with fibrillary cytoplasm and hyperchromatic nuclei. There was strong immunoreactivity to S-100 protein. A diagnosis of schwannoma was made. The patient underwent a wide local surgical excision of the mass via a combined Caldwell-Luc and endonasal endoscopic resection with medial maxillectomy. Final pathology was consistent with sinonasal schwannoma. Post-operatively, she is now able to breathe through her nose and is showing no evidence of disease three months from treatment. Bibliography: Adler ET, Cable BB, Casler JD, Greenspan RB. Pathologic quiz case 2. External nasal schwannoma. Arch Otolaryngol Head Neck Surg 1997;123:443-445. Berlucchi M, Piazza C, Blanzuoli L, Battaglia G, Nicolai P. Schwannoma of the nasal septum: A case report with review of the literature. Eur Arch Otorhinolaryngol 2000;257:402-405. Blokmanis A. Endoscopic diagnosis, treatment, and follow-up of tumours of the nose and sinuses. J Otolaryngol 1994;23:366-369. Buob D, Wacrenier A, Chevalier D, Aubert S, Quinchon JF, Grosselin B, Leroy X. Schwannoma of the sinonasal tract: A Clinicopathologic and immunohistochemical study of 5 cases. Arch Pathol Lab Med 2003;127:1196-1199. Cakmak O, Yavuz H, Yucel T. Nasal and paranasal sinus schwannomas. Eur Arch Otorhinolaryngol 2003;260:195-197. Donnelly MJ, al-Sader MH, Blayney AW. Benign nasal schwannoma. J Laryngol Otol 1992;106:1011-1015. Hasegawa SL, Mentzel T, Fletcher CD. Schwannomas of the sinonasal tract and nasopharynx. Mod Pathol 1997;10:777-784. Hawkins DB, Luxford WM. Schwannomas of the head and neck in children. Laryngoscope 1980;90:1921-1926. Hegazy HM, Snyderman CH, Fan CY, Kassam AB. Neurilemmomas of the paranasal sinuses. Am J Otolaryngol 2001;22:215-218. Higo R, Yamasoba T, Kikuchi S. Nasal neurinoma: Case report and review of the literature. Auris Nasus Larynx 1993;20:297-301. Khalifa MC, Bassyouni A. Nasal schwannoma. J Laryngol Otol 1981;95:503-507. Klossek JM, Ferrie JC, Goujon JM, Fontanel JP. Endoscopic approach of the pterygopalatine fossa: Report of one case. Rhinology 1994;32:208-210. Leakos M, Brown DH. Schwannomas of the nasal cavity. J Otolaryngol 1993;22:106-107. Leu YS, Chang KC. Extracranial head and neck schwannomas: A review of 8 years experience. Acta Otolaryngol 2002;122:435-437. Mannan AA, Singh MK, Bahadur S, Hatimota P, Sharma MC. Solitary malignant schwannoma of the nasal cavity and paranasal sinuses: Report of two rare cases. Ear Nose Throat J 2003;82:634-636, 638, 640. Marvel JB, Parke RB. Malignant schwannoma of the nasal cavity. Otolaryngol Head Neck Surg 1990;102:409-412. Mohan D, Krishna A, Ramakristnan V. Schwannoma presenting as a nasal tip deformity. Ann Plast Surg 1997;38:83-84. Nagayama I, Nishimura T, Furukawa M. Malignant schwannoma arising in a paranasal sinus. J Laryngol Otol 1993;107:146-148. Oi H, Watanabe Y, Shojaku H, Mizukoshi K. Nasal septal neurinoma. Acta Otolaryngol Suppl 1993;504:151-154. Pasic TR, Makielski K. Nasal schwannoma. Otolaryngol Head Neck Surg 1990;103:943-946. Pasquini E, Sciarretta V, Farneti G, Ippolito A, Mazzatenta D, Frank G. Endoscopic endonasal approach for the treatment of benign schwannoma of the sinonasal tract and pterygopalatine fossa. Am J Rhinol 2002;16:113-118. Ross C, Wright E, Moseley J, Rees R. Massive schwannoma of the nose and paranasal sinuses. South Med J 1988;81:1588-1591. Sarioglu S, Ozkal S, Guneri A, Ada E, Sis B, Erdag TK, Pabuccuoglu HU. Cystic schwannoma of the maxillary sinus. Auris Nasus Larynx 2002;29:297-300. Shugar MA, Montgomery WW, Reardon EJ. Management of paranasal sinus schwannomas. Ann Otol Rhinol Laryngol 1982;91:65-69. Srinivasan V, Deans JA, Nicol A. Sphenoid sinus schwannoma treated by endoscopic excision. J Laryngol Otol 1999;113:466-468. Trimas SJ, Stringer SP, Jordan JR. Malignant Schwannoma of the ethmoid sinus associated with AIDS. Ear Nose Throat J 1993;72:362-364. Wada A, Matsuda H, Matsuoka K, Kawano T, Furukawa S, Tsukuda M. A case of schwannoma on the nasal septum. Auris Nasus Larynx 2001;28:173-175. Yang TL, Hsu MC, Liu CM. Nasal schwannoma: A case report and clinicopathologic analysis. Rhinology 2001;39:169-172. Yaqoob N, Soomro I, Moatter T, Zaffar A. Coexicstence of benign schwannoma and lymphoma in a nasal polyp. J Laryngol Otol 2002;116:865-867. Younis RT, Gross CW, Lazar RH. Schwannomas of the paranasal sinuses. Case report and clinicopathologic analysis. Arch Otolaryngol Head Neck Surg 1991;117:677-680. Grand Rounds Archive | Department Home pageBCM Public | BCM Intranet | Privacy Notices | Contact BCM | BCM Site Map | ©2001-2005 Baylor College of Medicine
|