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Year : 2013  |  Volume : 10  |  Issue : 1  |  Page : 29-32

Hypopharyngeal schwannoma: A rare case presentation and review of literatures

1 Department of Otorhinolaryngology, Bayero University, Kano, Nigeria
2 Department of Pathology, Aminu Kano Teaching Hospital, P.M.B. 3452, Kano, Nigeria

Date of Web Publication29-Aug-2013

Correspondence Address:
Abdulazeez O Ahmed
Department of Otorhinolaryngology, Bayero University, Aminu Kano Teaching Hospital, Kano, P.M.B. 3452
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0331-8540.117243

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Schwannomas are benign tumors of nerve cells and are particularly quite rare in the hypopharynx. To our knowledge only nine cases have been reported world-wide. We present a 27-year-old Hausa/Fulani housewife who developed slowly progressive and unremitting hoarseness and foreign body sensation in the throat. She had indirect laryngoscopy at presentation with subsequent examination under anesthesia, which revealed a soft ovoid pinkish swelling arising from the posterior pharyngeal wall in the hypopharynx. After a preliminary tracheotomy, the mass was mobilized and delivered trans-orally. She made an uneventful recovery and was discharged home. This uncommon presentation further emphasizes the dilemma of access and approach posed by hypopharyngeal masses.

Keywords: Hoarseness, hypopharynx, schwannoma, transoral

How to cite this article:
Ahmed AO, Umar AB, Aluko AA, Yaro MA. Hypopharyngeal schwannoma: A rare case presentation and review of literatures. Niger J Basic Clin Sci 2013;10:29-32

How to cite this URL:
Ahmed AO, Umar AB, Aluko AA, Yaro MA. Hypopharyngeal schwannoma: A rare case presentation and review of literatures. Niger J Basic Clin Sci [serial online] 2013 [cited 2021 Dec 2];10:29-32. Available from: https://www.njbcs.net/text.asp?2013/10/1/29/117243

  Introduction Top

A Schwannoma is a benign, encapsulated tumor derived from schwann cells. Schwannomas are relatively rare and their distribution is controversial. As such very little literature is available about them. The majority of information regarding these tumors has been obtained from scattered case reports. It has no particular gender predilection and occurs around the third and fourth decades of life. [1] Approximately, 25-48% of schwannomas occur in the head and neck region, but the intra-pharyngeal occurrence is extremely rare. [2] When they do occur in the pharynx, they cause dyspnea and dysphagia or impair phonation. They rarely recur after complete surgical removal; however one must always bear in mind the possibility of neurological sequelae. The presentation, clinical findings and management options are discussed with particular attention to the literature. From available literature, this is the first Nigerian case of a hypopharyngeal schwannoma.

  Case Report Top

We present a 27-year-old Hausa Fulani housewife who presented with a 3 year history of an insidious onset of gradually progressive hoarseness, unremitting with associated feeling of foreign body sensation in the throat. However, she had no difficulty in breathing, cough and odynophagia, but she had some mild dysphagia.

She had no neck swellings or history of voice abuse. She did not have otalgia or any other otologic symptom. The other systems were essentially normal.

Examination was not remarkable, but during indirect laryngoscopy (IDL) an ovoid mass with visibly dilated veins on its surface was seen and the tumor appeared to be arising from the posterior pharyngeal wall and abutting on the laryngeal inlet with consequent partial occlusion.

X-ray lateral soft tissue neck revealed a soft-tissue shadow arising from the posterior pharyngeal wall in the hypopharynx abutting on the laryngopharynx (not shown here as it was later damaged due to water accidently spilling over the film).

During Examination, under Anesthesia (EUA) a preliminary tracheotomy was effected to secure the airway. A firm pedunculated 3 cm × 3.5 cm round and smooth mass was visualized with a healthy mucosa and a broad stalk arising from the posterior pharyngeal wall. Due to financial constraints and other logistics, EUA and definitive surgery was undertaken in one sitting. The mass was mobilized via a submucosal incision and with gentle dissection complete excision of the hypopharyngeal mass was achieved transorally [Figure 1].
Figure 1: Gross specimen showing cleavage line with homogenous gray white surfaces and myxoid areas

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Hemostasis was spontaneous with the added use of adrenaline impregnated gauze pressure packing. Recovery was uneventful. She was decannulated 3 days later without respiratory difficulty or hoarseness.

She made remarkable improvement and was discharged home 9 days later. The gross specimen was a pink greyish mass weighing 0.50 g and measuring 3 cm × 3.5 cm across. Histopathologic section revealed a fairly well demarcated tumor characterized by a cellular and paucicellular areas. The cellular (Antoni A) areas are composed of palisaded spindle cells with wavy nuclei and moderate fibrillary cytoplasm disposed in organoid patterns with scanty matrix (Verocay bodies). The less cellular (Antoni B) areas show paucity of the spindle cells separated by abundant edematous and myxoid matrix. H and E staining revealed classical features of a schwannoma [Figure 2] and [Figure 3]. Immunohistochemical stain with S100 were diffusely positive; thus, further confirming the diagnosis [Figure 4]. She has since been followed-up carefully for 4 years now without sequelae.
Figure 2: Tumor characterized by cellular Antoni A and looser myxoid Antoni B areas (H and E, ×10)

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Figure 3: Micrograph showing close up of the schwann cells with serpentine nuclei and moderate fibrillary cytoplasm (H and E, ×40)

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Figure 4: Confirmatory photomicrograph showing strong diffuse positivity with S100

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  Discussion Top

In a resource poor-setting such as ours or developing countries in general, assessment of the mass with a flexible fiberoptic nasopharyngoscope at presentation would have cut down by more than half the time taken to arrive at a clinical diagnosis as well as deciding on the approach for tumor removal. At the time of seeing this patient, a flexible nasoendoscope was not available in our center. Therefore, IDL was initially utilized. This further substantiates the fact that IDL cannot be dispensed with in the diagnostic armamentarium of the present day head and neck surgeon.

Schwannomas are slow-growing tumors with a low incidence when their site of election is considered. Differentiation between schwannomas in the oropharynx, larynx and hypopharynx in previous studies were often unclear. A review of available case reports revealed only nine histologically confirmed hypopharyngeal schwannomas. [3],[4],[5] Schwannomas may occur in association with neurofibromatosis or arise sporadically. To our knowledge, this is the first Nigerian case of a true schwannoma in the hypopharynx. Recent reports reveal a total of 110 cases of "pedunculated polyps" in the esophagus and hypopharynx combined. [6] Similarly, Koide et al. (1992) reported about 57 cases all of benign hypopharyngeal tumors of varying histopathological types: Lymphangiomas, neurofibromas, lipoma, hemangiopericytoma, hemangioma, etc. [7]

According to the literature, both sexes and all age groups are equally affected with incidences in the third to fifth decade as seen in this patient and described by various authors. [8],[9]

In order of occurrence, the cranial nerves most commonly involved are 9 th , 7 th , 11 th , 5 th , and 4 th . The vagus, lingual, recurrent laryngeal nerves, posterior pharyngeal wall and the larynx are "infrequently" affected sites. [7] Similarly, isolating the particular nerve involved during enucleation or excision may not be practical without untoward effects.

The onset of symptoms is varied and depends on the size of the lesion. The presentation is usually in the form of sore throat, odynophagia, dysphagia, dyspnea, stridor, hoarseness, and sensation of a lump in the throat. This patient presented with hoarseness and foreign body sensation in keeping with benign hypopharyngeal masses. These salient features manifested mainly due to pressure effects of its sheer size and local pressure effect, which is also peculiar to schwannomas. [10]

Malignant hypopharyngeal neoplasms in contrast, may present in addition to the above, with a recent onset of symptoms with rapid progression, progressive weight loss and cervical swellings. In our index case, none of the aforementioned was noted and she had a 3-year history prior to the presentation.

Imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI) are also invaluable in the evaluation of schwannomas. The imaging is best carried out before any type of biopsy so as to have an undisturbed mucosa for proper evaluation. [11] On CT, they appear isodense, but up to 20% of these tumors may display hypodense areas. On the other hand, with MRI, a schwannoma is indicated by intermediate intensity and can hardly be differentiated from muscle on T1 scans. On T2 scans, the intensity of a schwannoma increases. Therefore, the inhomogeneous structure and the cystic areas are represented by low intensity on T1 scans and as high intensity on T2 scans. [12] Both of these imaging modalities also foretell extent of involvement of contiguous structures. Unfortunately, due to financial reasons our patient could not afford a CT scan much less an MRI, which was not available at the time anyway.

The option for treatment is essentially surgery and surgical treatment of choice is complete enucleation/excision and preservation of function of affected nerve/site, utilizing various approaches as determined by size and location of the lesion. Via endoscopic, open transoral, and external or lateral pharyngotomy approaches could be utilised. Small tumors can be excised easily by endoscopic and transoral routes while larger tumors are easily extirpated via lateral pharyngotomy approaches. In this patient, a transoral approach was utilized due to its relatively small size although with minimal room for manipulation.

Histologically, schwannomas have two different patterns: Antoni A and B areas. The former describes a cellular area in which sheets of spindle-shaped cells are often arranged in a palisading fashion, called Verocay bodies. The latter is composed of myxoid, loose, degenerative areas. Moreover, S100 protein positivity with no demonstrable mitotic activity is suggested to be characteristic of these cellular areas. [2] The histological pattern of this lesion with Antoni A and B as well as the S100 protein expression helped to confirm the diagnosis of schwannoma in this patient.

In our case, the major challenge was working in a narrow cavity and ensuring adequate resection margins without sequelae. We were unable to trace the nerve of origin, but we assume this to be the vagus or glossopharyngeal nerve. This further emphasizes the difficulty in the surgical removal of hypopharyngeal tumors. The prognosis is usually good with adequate tumor removal as evidenced by our patient who has been followed-up for almost 4 years without any sequelae. The rarity and diagnostic challenge of this case warrants reporting especially for the unwary aerodigestive surgeon in a resource-poor setting.

  References Top

1.Parvathidevi GK, Panduranga C, Munishwar GB. "Ancient" schwannoma of hypopharynx: A case report with review of literature. Indian J Otolaryngol Head Neck Surg 2011;63:60-1.  Back to cited text no. 1
2.Ecevit MC, Erdag TK, Guneri A, Sarioglu S, Guneri EA. A schwannoma mimicing hypopharyngeal carcinoma. Eur Arch Otorhinolaryngol 2006;263:469-72.  Back to cited text no. 2
3.Hiratsuka Y, Takagi A, Tokuda Y. A case of hypopharyngeal neurinoma. Pract Otol 1995;86:46-7.  Back to cited text no. 3
4.Sasaki K, Murai N, Yoshida H. A case of a hypopharyngeal schwannoma. Pract Otol 1998;91:373-6.  Back to cited text no. 4
5.Morvan JB, Veyrières JB, Mimouni O, N'Guyen AT, Fouet B, Cathelinaud O, et al. Solitary fibrous tumour of the larynx: A case report. Eur Ann Otorhinolaryngol Head Neck Dis 2011;128:262-5.  Back to cited text no. 5
6.Caceres M, Steeb G, Wilks SM, Garrett HE Jr. Large pedunculated polyps originating in the esophagus and hypopharynx. Ann Thorac Surg 2006;81:393-6.  Back to cited text no. 6
7.Koide C, Imai A, Takahashi T. Benign hypopharyngeal tumor: Report of two cases. J Jpn Bronchoesophagol Soc 1992;43:492-9.  Back to cited text no. 7
8.Feany MB, Anthony DC, Fletcher CD. Nerve sheath tumours with hybrid features of neurofibroma and schwannoma: A conceptual challenge. Histopathology 1998;32:405-10.  Back to cited text no. 8
9.Oka A, Nakashima T, Miyahara T, Tachi T, Nishida N, Kazunori N. Hypopharyngeal schwannoma-A case report. J Okayama Saiseikai Gen Hosp 2004;36:28-33.  Back to cited text no. 9
10.Singh B, Ramjettan S, Maharaj TP, Ramsaroop R. Schwannoma of the posterior pharyngeal wall. J Laryngol Otol 1995;109:883-5.  Back to cited text no. 10
11.Pameijer FA, Mukherji SK, Balm AJ, van der Laan BF. Imaging of squamous cell carcinoma of the hypopharynx. Semin Ultrasound CT MR 1998;19:476-91.  Back to cited text no. 11
12.Pilavaki M, Chourmouzi D, Kiziridou A, Skordalaki A, Zarampoukas T, Drevelengas A. Imaging of peripheral nerve sheath tumors with pathologic correlation: Pictorial review. Eur J Radiol 2004;52:229-39.  Back to cited text no. 12


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

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