|Ahead of print publication
Malignant peripheral nerve sheath tumor of the parapharyngeal space arising from cervical sympathetic chain: A rare entity
Roshan K Verma1, Vimmi Gautam1, Amit Bahl2, Amanjeet Bal3
1 Department of Otolaryngology, Head and Neck Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Radiotherapy, Postgraduate Institute of Medical Education and Research, Chandigarh, India
3 Department of Histopathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
Roshan K Verma,
Department of Otolaryngology, Head and Neck Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
Source of Support: None, Conflict of Interest: None
Malignant peripheral nerve sheath tumors (MPNSTs) of parapharyngeal space are rare and if present are most often in association with neurofibromatosis type 1 (NF-1). Only a few cases of MPNST have been reported in the literature without coexisting NF. We report one such case of an MPNST of parapharyngeal space tumor in a 35-year-old female with no associated features of NF-1. She presented with right-sided neck swelling and ptosis. Magnetic resonance imaging showed a 7 cm × 8 cm × 11 cm irregular swelling in the right parapharyngeal space with invasion of surrounding muscles. The mass was excised using a transcervical approach. Postoperative histopathological examination of the specimen revealed MPNST possibly arising from the cervical sympathetic chain.
Keywords: Cervical sympathetic chain, malignant peripheral nerve sheath tumor, magnetic resonance imaging neck, parapharyngeal space, ptosis
|How to cite this URL:|
Verma RK, Gautam V, Bahl A, Bal A. Malignant peripheral nerve sheath tumor of the parapharyngeal space arising from cervical sympathetic chain: A rare entity. J Can Res Ther [Epub ahead of print] [cited 2020 Jul 7]. Available from: http://www.cancerjournal.net/preprintarticle.asp?id=264210
| > Introduction|| |
Malignant peripheral nerve sheath tumors (MPNSTs) are a histological subtype of soft-tissue sarcoma, accounting for 5%–10% of all soft-tissue sarcomas., MPNST is the term coined by the World Health Organization. They are highly aggressive tumors capable of arising de novo or from preexisting benign neurofibromas or schwannomas. It represents malignant proliferation of any cell of the nerve sheath-like Schwann cells, perineural fibroblast, or end neural fibroblast.
About 25%–70% of these MPNSTs are associated with neurofibromatosis (NF) and 9%–14% occur in the head and neck. The lifetime risk of MPNST in NF-1 is 8%–13% as compared to 0.001% in the general population. Very few case reports of MPNST have been reported in patients with no evidence of NF. We report one such case in our report.
MPNST is a highly aggressive tumor and carries poor prognosis. MPNSTs are generally considered to be resistant to chemotherapy and radiotherapy. Treatment with surgical excision and aggressive postoperative radiotherapy and chemotherapy gives the best chance for survival.
This case report describes an unusual MPNST of the parapharyngeal space in a patient with no associated stigmata of NF and unique radiological features and treatment approaches to be followed in such cases after reviewing the literature.
| > Case Report|| |
A 35-year-old female presented to our outpatient department with complaints of progressive swelling on the right side of the neck for 6 months. She complained of pain over the swelling which was relieved with analgesics. She noticed swelling inside the right side of the oral cavity for 2 months. She complained of change in voice for 2 months. Her voice was muffled, and there was loss of nasal twang in the voice. She complained of difficulty in opening the mouth and difficulty in swallowing food for 1 month, for which Ryle's tube was inserted by local practitioner. She also complained of drooping of right eye for 2 months.
On local examination of the neck, a diffuse 8 cm × 6 cm swelling was present on the right side of the neck and face extending from the zygomatic arch to the till upper border of cricoid cartilage. Mediolaterally, the swelling was extending from the nasolabial fold to the front of tragus. The swelling was nontender, noncompressible, nonpulsatile, and firm in consistency. The swelling had restricted mobility. Intraoral examination showed a 3 cm × 3 cm bulge over the right side of the soft palate completely stretching it, and the bulge also extended to involve the right buccal mucosa up to the upper third molar region with ulceration of size 1 cm × 1 cm in that region. The tonsils were pushed medially. The patient had grade II trismus. Examination of the right eye showed mild ptosis. Her visual acuity was 6/6 and pupils were normal size. There was no loss of ciliospinal reflex. There was no dysfunction of lower cranial nerves (V, VII, IX, X, XI, and XII) and no stigma of NF type 1 (NF-1) was seen [Figure 1].
|Figure 1: Preoperative photographs of patient front, lateral view, and intraoral bulge|
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Routine blood investigations and 24-h urinary catecholamines were within normal limits. Computed tomography (CT) scan of the neck showed heterogeneously enhancing 11 cm × 8 cm soft-tissue swelling in the right parapharyngeal space extending superiorly into the infratemporal fossa till the level of hyoid bone inferiorly [Figure 2]. Magnetic resonance imaging (MRI) neck showed 7 cm × 8 cm × 11 cm irregular lobulated swelling in the right parapharyngeal space superiorly involving the infratemporal fossa abutting right anterior temporal pole with no dural breach, and inferiorly, the lesion was involving the tongue base and palatine tonsil and invading the submandibular space. Medially, the lesion was displacing the pharyngeal mucosa contralaterally with narrowing of nasopharynx and oropharynx. Posteriorly, the prevertebral muscles were effaced and appeared infiltrated. The swelling was isointense on T1 and hyperintense on T2 with multiple foci of central nonenhancing areas [Figure 2]. Fine-needle aspiration cytology was done which was reported as spindle cell tumor.
|Figure 2: Computed tomography and magnetic resonance imaging of the patient showing heterogeneously enhancing lesion in parapharyngeal with effacement of fat and infiltration of muscles|
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Wide excision of the mass was performed by transcervical approach. The mass was excised in toto and the specimen measured 14 cm × 7 cm × 5 cm. The exact site of origin could not be made out due to large size of the tumor [Figure 3]. The mass appeared to be pinkish white with multiple lobulations on gross examination, and the cut surface was yellowish white in appearance with central areas of necrosis. Postoperatively, she developed Horner's syndrome [Figure 4].
|Figure 3: Intraoperative image and cut section of tumor showing necrosis within tumor|
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|Figure 4: Postoperative image of the patient along with endoscopic view showing no bulge in the oropharynx|
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Microscopic examination showed well-circumscribed highly cellular tumor with infiltrating margins. The tumor was composed of sheets and fascicles with spindle cells, moderate atypia, and round-to-oval hyperchromatic nuclei. Frequent mitosis (1–4 per hpf) was noted with areas of necrosis. Tumor was diffusely positive for vimentin and S-100 and negative for EMA, P63, and SMA. Based on this histological finding, a diagnosis of MPNST was made [Figure 5].
|Figure 5: Histopathology showing sheets of spindle-shaped cells with occasional mitosis and immunocytochemistry showing strong vimentin positivity and weak S-100 positivity*|
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The patient was discussed in our head and neck tumor. Board CT chest and CT abdomen showed no evidence of distant metastasis. She was advised for adjuvant radiotherapy. A total of 60 Gy given for 6 weeks was planned. She came for follow-up 1-month back and is doing fine now.
| > Discussion|| |
Peripheral nerve sheath tumors are tumors arising neural crest derivatives (Schwann cells, perineural cells, and fibroblast) and include neurofibroma, schwannoma, and MPNST. MPNSTs are aggressive soft-tissue neoplasm arising from peripheral nerves. The incidence of MPNST in general population is 0.001%. They usually occur in the age group of 20–50 years and show an almost equal sex distribution.
They can occur sporadically or in patients with NF-1 (20%–50% of MPNSTs). Most of the MPNSTs arise within preexisting plexiform neurofibromas or perineuriomas. MPNST is more common in patients with a family history of NF and warrants increased surveillance for development of these tumors. However, our case had no stigmata of NF and had no family history of NF.
MPNSTs are most commonly found on the extremities and trunk, are rare in head and region (10% of all MPNSTs), and are even rarer in parapharyngeal space. MPNSTs of parapharyngeal space usually present as painful rapidly enlarging mass with associated neurological deficit. The vagus nerve is the main nerve to be involved in neck, and therefore, hoarseness is a common presenting symptom. Our case had ptosis of the right eye at presentation which suggests that cervical sympathetic chain could be the nerve of origin.
The clinical differential diagnosis of such tumor in parapharyngeal space includes salivary gland tumors, neurogenic tumors, skull base and vertebral tumors such as meningioma and chordoma, rhabdomyosarcoma, Castleman's disease, arteriovenous malformations, and lymphangiomas.
Both CT scan and MRI are required to evaluate tumors of parapharyngeal space. MRI is the imaging modality of choice for suspected case of MPNST. MRI can reveal the nerve of origin and is more accurate to evaluate the topographical relationship of the tumor with neighboring structures, especially vascular, muscular structures and fat planes involvement. Features favoring the diagnosis of MPNST on MRI are size of the mass (>5 cm), invasion of fat planes, heterogeneity, ill-defined margins, and edema surrounding the lesion., Metastasis of these tumors occurs mainly to the lungs and bones. Therefore, CT of the chest is recommended after the diagnosis has been established by histopathological examination. If the tumor appears as enhancing lesion, CT angiography is also recommended.
Histologically, MPNST resembles spindle cell sarcoma. Microscopically, MPNST is highly cellular and consists of spindle cells arranged in bundles or fascicles. Mitotic figures may suggest malignant pathology. Immunocytochemistry show strong positivity for vimentin and weak positivity for S-100.
The treatment of choice for MPNST of paraphayrgeal space is radical surgical resection. The surgical excision can be done with transoral, transcervical, transparotid–transcervical, transcervical–transmandibular, or infratemporal approaches. The appropriate choice of surgery depends on the mass size and location of tumor. Sometimes, these large parapharyngeal tumors may require lateral mandibulotomy and preoperative tracheostomy to improve the access to parapharyngeal tumor, especially those eroding the skull base. A preoperative plan for lateral mandibulotomy was made to improve access for tumor removal in our case. However, during surgery, we were able to remove whole tumor in toto without lateral mandibulotomy. We had small pharyngeal rent for which pharyngeal repair was done and Ryles tube was put for 7 days. Sometimes, a tracheostomy may be required in the postoperative period in such cases.
Despite the fact that these tumors are considered to be resistant to chemotherapy and radiotherapy, postoperative radiotherapy is recommended by the Oncology Consensus Group as part of a uniform treatment policy. MPNSTs are resistant to chemotherapy; however, isolated case reports have shown chemotherapy to be effective and can be considered in surgical failures and inoperable cases. Chemotherapy with dacarbazine, doxorubicin, and ifosfamide has shown to control tumor growth in MPNST.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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