| Abstract|| |
Malignant peripheral nerve sheath tumor (MPNST) is a rare pathologic lesion in a patient with solitary neurofibroma. A 32-year-old man presented with a firm and slightly tender mass in the right infratemporal region involving the right preauricular and temporomandibular joint area. The patient has a history of removal of a solitary neurofibroma 22 years back in the same region. The lesion had enlarged rapidly over the past 3 months, and a spindle cell lesion was diagnosed through a superficial incisional biopsy. Surgical removal of the lesion using modified preauricular transzygomatic approach was done. Histopathologically, it was diagnosed as an MPNST.
Keywords: Infratemporal fossa, malignant peripheral nerve sheath tumor, neurofibroma, surgical removal
|How to cite this article:|
Balaji S M, Balaji P. Transzygomatic, transcondylar excision of the sarcoma of infratemporal fossa. Indian J Dent Res 2019;30:318-21
|How to cite this URL:|
Balaji S M, Balaji P. Transzygomatic, transcondylar excision of the sarcoma of infratemporal fossa. Indian J Dent Res [serial online] 2019 [cited 2020 Jul 10];30:318-21. Available from: http://www.ijdr.in/text.asp?2019/30/2/318/259218
| Introduction|| |
Malignant peripheral nerve sheath tumors (MPNSTs) are a group of soft-tissue neuronal tumors that are reported to arise from the peripheral nerves. They often display differentiation of various elements of the nerve sheath such as the Schwann cells, perineural fibroblasts, or fibroblasts. It is reported that about 10% of MPNSTs occur in the head-and-neck region., They have been reported to arise from peripheral nerves or from a preexisting neurofibroma within a neurofibromatosis type-1., Reported cases of intracranial MPNSTs are usually associated with an intracranial nerve when seen in adults., The manuscript intends to present a case of MPNSTs occurring in a middle-aged male with a history of solitary neurofibroma.
| Case Report|| |
A 32-year-old male patient of Southeast Asian decent reported to the hospital with a chief complaint of swelling in the right preauricular region for the past 3 months. He had a history of surgical removal of a tumor in the same region before 22 years in our hospital that was excised in toto and histologically identified as neurofibroma. After that, it had recurred twice and had been surgically removed elsewhere. The patient had neither familial history nor any relevant medical history. On physical examination, the patient presented with a marked facial asymmetry of the right half of the face. On clinical examination, there was a mild diffuse swelling in the right temporal region. The swelling was soft in inconsistency and nontender on palpation. Skin over the swelling was pinchable, with no secondary surface changes. The previous surgical scar was visible. The swelling extended from the right temple region and involved the entire right cheek, and anteroposteriorly, it extended from the lobule to the nasolabial fold. There was obliteration of the nasolabial fold.
Magnetic resonance imaging studies revealed a large soft-tissue mass of mixed density measuring approximately 4.21 cm × 4.55 cm within the right infratemporal fossa (ITF). The lesion exhibited alternating isointense and hyperintense areas in T1- and T2-weighted images. A few hypointense areas were noted in the mass lesion suggestive of spicules of destroyed bone. At one focus, there was an area suggestive of hemorrhage or necrosis seen within the lesion. The mass lesion showed contiguous extension to involve parts of the temporal bone, the medial and lateral pterygoid musculature of the right side with erosion of the pterygoid plate, and posterolateral wall of the right maxilla and inferior aspect of greater wing of sphenoid bone. Furthermore, the pterygoid hamulus, the upper regions of the pharynx, and the large parts of the right posterior part of maxillary bone were involved. It extended outward through the ITF with intense postcontrast enhancement. At certain areas, the lesion was not clearly demarcated and the entire lesion did not involve the buccinator complex but infiltrated the temporalis, masseter, and medially extended up to the foramen ovale to the dura mater. Caudally, the lesion was extending toward the hard palate with destruction of a part of the maxillary antrum. The anterior wall of the maxilla was destroyed with extension of the mass lesion into subcutaneous plane of the premaxillary area. The posterior wall was breached at certain places to involve the retromaxillary fat pad. No significant cervical lymphadenopathy was observed clinically or in the scan [Figure 1]a,[Figure 1]b,[Figure 1]c.
|Figure 1: Imaging findings. (a) Axial view at middle level; (b) axial view at superior level; (c) coronal view. Arrows denote extent of lesion|
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Histopathological studies of the incisional biopsy (done previously elsewhere) were that of an aggressive spindle cell lesion that exhibits pleomorphism with a diagnosis of sarcoma. Surgical removal of the mass was planned under general anesthesia.
Under general anesthesia, standard surgical preparation was done. The standard preauricular transzygomatic approach to the region was performed., For this, a semicoronal incision was made in front of the right ear along the previous surgical scar and the underlying tissues were reflected [Figure 2]a,[Figure 2]b,[Figure 2]c,[Figure 2]d,[Figure 2]e,[Figure 2]f. The temporalis muscle was exposed, cut at its origin, and reflected to expose the skull bone below. The zygomatic arch, coronoid process, and a part of the temporal bone were osteotomized to access and excise the lesion. The tumor was visualized as shown in the schematic diagram. The lesion was removed in its entirety. The cut margins were immediately processed for accessing the surgical margins using frozen section. There was marginal clearance in all areas, except the pterygopalatine fossa, where further clearance was obtained. As there were susceptive adhesions in the bone fragments of the surgical window, the surgical region was closed with muscles and adjoining soft tissues. The remaining temporalis muscle was repositioned. The wound was closed intraorally, with drain placement, using a 4-0 vicryl and extraoral preauricular incision with staples [Figure 3]a,[Figure 3]b,[Figure 3]c,[Figure 3]d,[Figure 3]e,[Figure 3]f. Postoperative results were satisfactory with better healing of wound and esthetics. Standard postoperative antibiotics and nonsteroidal anti-inflammatory drugs were provided. The patient was observed for a week for any evidence of cerebrospinal fluid leakage. The healing was uneventful [Figure 4]a,[Figure 4]b,[Figure 4]c,[Figure 4]d.
|Figure 2: Schematic diagram. (a) Surgical outline; (b) incision for osteotomy of coronoid condylar process, zygoma, and temporal bone; (c) removal coronoid–condylar, zygomatic process; (d and e) temporal bone window; (f) tumor access and visualization|
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|Figure 3: Intraoperative picture. (a) Dissection to reach the infratemporal region; (b) identifying vital structure; (c) visualization of the tumor; (d) temporal fossa window; (e) closure of the incision; (f) surgical specimen|
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|Figure 4: (a) Low-power, hematoxylin and eosin stain, scan view showing the spindle cell lesion with wavy nuclei – Note the pleomorphism. (b) Low-power view of the lesional tissue – Note the shape of the nuclei and blood vessel; (c and d) High power of the lesional tissue – showing the pleomorphic, vesicular nuclei, and characteristic blood vessels developing inside the lesion|
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The postoperative specimen with hematoxylin and eosin show a predominantly cellular spindle cell neoplasm composed of interlacing fascicles of spindle cells with mild-to-moderate nuclear atypia and elongated vesicular to hyperchromatic nuclei. A mitotic count of 14 per 10 high power filed was noted. Focal areas of necrosis were noted. Focally, the tumor invades skeletal muscle fibers at the periphery, interspersed between the spindle cells and “staghorn-”type blood vessels. Extravasated red blood cells are seen. The diagnosis of a spindle cell lesion was arrived at and immunohistochemistry studies were performed. The lesional cells were positive for vimentin, focally for smooth muscle actin, and negative for desmin. The tumor cells show loss of nuclear expression for H3K27ME3 in vast majority of the tumor cells, and focally, the tumor demonstrates a mosaic pattern (few positively and few negatively stained nuclei). CD99 shows weak cytoplasmic staining and is noncontributory. A solitary fibrous tumor was excluded by negative STAT6 results. The lesion was negative for S100, SOX10, CK, EMA, CD34, desmin, and TLE1.
| Discussion|| |
This case posed dual challenge – one is the diagnostic challenge and the other is the management challenge. There are very few cases in the IFT region wherein isolated neurofibroma turned to MPST., The patient had been previously operated on about 22 years back and been on follow-up with his medical healthcare provider. In spite of the follow-up, the lesion showed aggressive growth over the last 3 months – an indication of recent spurt in tumor activity. MPNST develops from the peripheral nerve sheath cells., In the head and neck region, they can arise in any part, except the optic and olfactory cranial nerves, as they lack Schwann cell sheaths. MPNSTs arising from the IFT region in a preexisting neurofibroma are not uncommon, as in our case. In about 50% of the cases, MPNST presents with neurologic symptoms. However, in the present case, there was no paresthesia, atypical pain, numbness, and weakness. The treatment demands the lesion to be completely excised to avoid local recurrence. The nature of the resection is dictated by the location and extent of the tumor., As in this case, the resections are often highly customized as in the present case. Often for high-grade tumors, the radiation and chemotherapy are to be followed. The overall and 5-year survival of MPNST has been reported to be about 40% to 60%. In the presence of predisposing neurofibroma, the survival rates are reported to drop down to 21% to 23%. The patient is currently being followed up and remains disease-free for the past 24 months.
There are a vast number of differential diagnoses for a spindle cell lesion of head and neck. In the present lesion, the diagnosis of myofibroblastic sarcoma or MPNSTs was arrived at through the clinical, radiological and spindle cell lesional histopathological features of focal necrosis, increased mitotic index and immunohistochemistry panel. As there was a prior lesion of neurofibroma, a final diagnosis of MPNST was more favored than the myofibroblastic sarcoma.
The lesion is situated in anatomically complex IFT area. Till the 1960s, the area was considered to be a surgical challenge. The innovation in this front was proposed by Conley and Barbosa, and it was Fisch who proposed various ITF approach.,, Fisch described four types of classic IFT approach (types A, B, C, and D) for accessing the skull base lesions. However, they suffer from a higher chance of middle and inner ear damage. The presently used preauricular transzygomatic approach provides a good exposure of the lateral skull base, as in the present case. Furthermore, it provides an operator with a sufficient control of the vascular and nervous structures. As in the present case, it facilitates enlargement options to reach anterior parts of maxillary sinus, medial parts of nasopharynx, and even parapharyngeal spaces without need for additional extensions. The approach has been evolved over the years., The intracranial extensions have reached the base of skull wherein it had caused resorption of certain bones. Furthermore, the involvement of the lesional extension along the cranial part of the foramen ovale was also observed. A unique combination approach was performed. A preauricular transzygomatic approach was used to reach the lesional site. As the lesion size was large, the removal of the portion of the zygoma, coronoid process, and temporal bone for proper access was essential. Furthermore, this provided a unique opportunity to remove the lesion in toto and to avoid spillage. The technique, though performed rarely, has a high degree of success when properly performed.
In the present case, though the lesion was much aggressive, postoperatively, the patient is faring well with no clinical evidence of the disease even after 24 months. There was no evidence of any postsurgical neurological or musculoskeletal abnormalities. The patient is still under medical supervision.
| Conclusion|| |
A rare case of MPNTs arising from a solitary neurofibroma of the IFT region has been reported. The successful surgical approach using a modification of the previously described techniques of IFT region access has been discussed.
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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Dr. S M Balaji
Balaji Dental and Craniofacial Hospital, 30, KB Dasan Road, Teynampet, Chennai - 600 018, Tamil Nadu
Source of Support: None, Conflict of Interest: None
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