Solitary malignant schwannoma of the nasal cavity and paranasal sinuses: report of two rare cases.
Malignant schwannomas of the paranasal sinuses are extremely uncommon tumors, as only 18 well-documented cases have been previously published in the English-language literature. We report two new cases of solitary malignant schwannoma--one in a 23-year-old man and the other in a 45-year-old woman. Neither was associated with von Recklinghausen's disease. These tumors involved the maxillary sinus, nasal cavity, and orbit and extended intracranially. Following surgery, both patients experienced recurrences. The male patient developed a slowly enlarging intranasal mass at the same site 8 years following excision of the original tumor and postoperative radiotherapy. Microscopic examination of the recurrent tumor revealed that its features were similar histologically to those of the original. The female patient experienced a recurrence 1 year following her first operation.
Peripheral nerve sheath tumors can occur anywhere throughout the body, but they have a propensity for the head and neck region. (1,2) Malignant schwannomas are highly aggressive tumors of nerve sheath origin. (3) The can arise sporadically as isolated lesions, but more often they develop in association with yon Recklinghausen's disease. (4,5) The most common sites are the extremities, trunk, chest, and retroperitoneum. The head and neck re region is involved in fewer than 10% of cases, and involvement of the paranasal sinuses or nasal cavity is extremely rare.5,6 Only 18 well-documented cases of malignant schwannoma involving the paranasal sinuses or nasal cavity have been previously published in the English-language literature. (7-15) In this article, we report two new cases, both of which occurred in patients who had no evidence of histologic dedifferentiation or distant metastasis.
Patient 1. In January 1994, a 23-year-old man came to our ENT outpatient unit with a 3-year history of progressive nasal block, proptosis, and decreased vision in his left eye. Examination revealed swelling over the left cheek, which led to obliteration of the nasofacial groove. A large mass of variable consistency filled the left nasal cavity. The patient's left eye was pushed upward and its movement was restricted. Pupillary reaction to light was normal. His neck nodes were not palpable, and no stigmata of yon Recklinghausen's disease were observed.
Routine blood and serum chemistry panels revealed no abnormality, and the chest x-ray was normal. However, computed tomography (CT) detected a large expansile mass in the left maxillary and ethmoid sinuses, with destruction of the sinus walls, extension into the anterior cranial fossa, and evidence of intraorbital extension (figure 1).
[FIGURE 1 OMITTED]
The tumor was biopsied twice and misdiagnosed as a benign nerve sheath tumor. The patient was prepared for surgery with general anesthesia. Perioperatively, a large vascular mass was noted to be filling the left maxillary sinus, extending into the ethmoid sinus and the posterior wall of the maxilla, and eroding the orbital wall. The cribriform plate was dehiscent. The thickened dura was exposed, and a suprastructure maxillectomy was carried out, The specimen was submitted for histopathologic examination. The excised mass measured 5 x 4 x 1 cm and had a grayish-white cut surface. It was identified as a malignant schwannoma.
Postoperative CT revealed the presence of a residual mass in the ethmoid sinuses and nasal cavity and expansion of the underlying bone. The patient was treated with 56 Gy of external-beam radiotherapy delivered ill 28 fractions over 5 weeks. The mass regressed after radiotherapy, and the patient did well for 8 years.
In July 2002, the patient returned with a complaint of spontaneous-onset epistaxis and an enlarging intranasal mass at the site of the previous lesion. CT identified it as an expansile soft-tissue lesion that was occupying the roof of the nasal cavity with destruction of the cribriform plate and extension into the ethmoid air cells bilaterally. There was no evidence of intracranial extension. Following the administration of general anesthesia, the mass was excised via a left lateral rhinotomy approach, and pathologic examination revealed the presence of multiple soft-tissue fragments. No adjuvant therapy was recommended. At the 4-month follow-up, the patient had not exhibited any evidence of recurrence.
Patient 2. In April 1995, a 45 year-old woman with a 3-month history of nasal obstruction was misdiagnosed with a benign nerve sheath tumor in the nasal cavity. She underwent surgery at a private hospital twice within a 6-month period--once for removal of the original mass and again for excision of a recurrence. Nine months following the second operation, she was examined after an episode of epistaxis and was found to have a mass in her right nasal cavity.
Nonenhanced CT revealed the presence of an isodense lesion that involved the right nasal cavity and right maxillary antrum and extended intracranially into the anterior cranial fossa. CT with contrast injection showed that the mass was enhancing homogeneously (figure 2). With the patient under general anesthesia, the minor was excised via a right lateral rhinotomy approach. The mass measured 8 x 7 x 1.5 cm and contained multiple polypoidal soft-tissue fragments. On macroscopic examination, the cut surface was grayish-white and exhibited focal myxoid areas, The lesion was diagnosed as a malignant schwannoma. The patient was discharged and kept under surveillance without any adjuvant therapy.
[FIGURE 2 OMITTED]
One year later, she returned with a 3-month history of another right nasal growth. On examination, the mass was foul-smelling and necrotic, and it filled the entire right nasal cavity. CT showed that the mass was confined to the right nasal cavity. Again, the tumor was excised and sent for histopathologic examination, which identified multiple soft-tissue fragments. The patient was then lost to follow-up.
Pathologic examination. In both patients, microscopic examination showed that the original tumor and the recurrent mass had similar morphologic features. Both were made up of sheets of spindle cells with indistinct cell outlines and a moderate amount of cytoplasm. The nuclei were oval to spindle-shaped and exhibited moderate pleomorphism. The mitosis rate in the very cellular area was 3 to 4 per 10 high-power fields (hpf). No areas of necrosis were identified in any of the tumors. In both patients, the original tumor had infiltrated as far as the epithelial lining of the nasal mucosa. Immunohistochemistry for S-100 protein (dilution: 1:100) (figure 3) and neuron-specific enolase (dilution: 1:50) showed strong positivity in the tumor cells but was negative for epithelial membrane antigen (dilution: 1:50) and glial fibrillary acid protein (dilution: 1:5,000). A final diagnosis of malignant schwannoma (neurofibrosarcoma) was arrived at in both cases.
[FIGURE 3 OMITTED]
The appearance of a malignant schwannoma in the paranasal sinuses or nasal cavity--with (7) or without (8,9,11-13) von Recklinghausen's disease--is extremely rare. In large series of patients with malignant schwannomas, Ghosh et al, (5) Das Gupta and Brasfield, (6) and D'Agustino et al (16) found no case that involved the paranasal sinuses. In an extensive review of 430,000 cases of nonepithelial tumors of the nasal cavity, paranasal sinuses, and nasopharynx, Perzin et al found only four cases of malignant schwannoma. (14) In a review of 48 cases of nasal and paranasal sarcomas by Sercarz et al, only one case of malignant schwannoma was seen. (15)
In the paranasal sinuses, malignant schwannomas arise from the ophthalmic and maxillary divisions of the trigeminal nerve or its terminal branches. Because they are so rare, their clinical presentation and behavior are not completely understood. Clinically, patients usually have an expansile mass, as did our two patients, that may be accompanied by pain at the site of the tumor or along the course of the Involved peripheral nerves. (6) Most of these tumors occur in patients between 20 and 50 years of age. (7,12) No predisposition to either sex or to any race has been identified. (6) One case of malignant schwannoma of the ethmoid sinus was associated with acquired immunodeficiency syndrome. (11)
Histologically, the differential diagnoses include fibrosarcoma, malignant fibrous histiocytoma, and benign schwannoma. The low degree of mitotic activity and the small size of the biopsy specimen in our patient 1 led to the misdiagnosis of benign schwannoma. Malignant schwannomas can be differentiated from fibrosarcomas and malignant fibrous histiocytomas by immunoreactivity for S100 protein and electron microscopy. Malignant schwannomas may exhibit divergent differentiation into heterologous elements, such as epithelial, cartilaginous, bony, and adipose tissue as well as rhabdomyoblasts (malignant triton tumor). (12)
If a malignant schwannoma is not completely excised, local recurrence is known to occur within a relatively short period of time. (14) Radical excision is often difficult because of the anatomy of the area. In our two cases, complete excision was not possible because the tumors extensively involved the maxillary sinus, nasal cavity, and orbit and extended into the cranial cavity. As is the case with other sarcomas, pulmonary metastasis is common; Youngerman et al reported that pulmonary metastasis occurred in 33% of patients with malignant schwannomas of the head and neck region. (2) Das Gupta and Brasfield reported that pulmonary metastasis occurred in 18 of 20 patients with malignant schwannomas of the head and neck who died with disease. (6) They found no nodal involvement at the time of postmortem examination. However, in both of these series, none of the tumors involved the paranasal sinuses. Death in cases of sinonasal malignant schwannomas is usually caused by direct invasion into the cranial cavity or by pulmonary metastasis. (14)
Wide en bloc resection without regional node dissection is the treatment of choice. (3,4) The usefulness of radiotherapy is controversial, (3) but some authors have advocated it. (8,9,17) In our patient 1, postoperative radiotherapy was administered because the tumor could not be completely excised, owing to its extensive local involvement and intracranial extension. The role of chemotherapy is also controversial. Chemotherapy has been advocated for patients with unresectable recurrent growths or pulmonary metastases, but it has no role as a primary modality in the treatment of malignant schwannomas. (18)
The prognosis depends on the degree of cellular pleomorphism and mitotic activity and on the size of the primary tumor. The prognosis is better for patients with low-grade tumors. (3) In the series of malignant schwannomas reported by Perzin et al, one patient with low-grade morphology (<5 mitotic figures per 50 hpf) had no evidence of recurrence 5 years following limited local excision. (14) Our patient I did well for 8 years before developing a local recurrence, and patient 2 developed a recurrence after 1 year. Therefore, some malignant schwannomas do appear to have a protracted course. Also, malignant schwannomas associated with neurofibromatosis have a worse prognosis than those that are not associated with von Recklinghausen's disease. (5,19,20) Neither of our patients had neurofibromatosis.
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From the Department of Pathology (Dr. Mannan, Dr. Singh, and Dr. Sharma), the Department of Otorhinolaryngology--Head and Neck Surgery (Dr. Bahadur), and the Department of Radiology (Dr. Hatimota), All India Institute of Medical Sciences, New Delhi.
Reprint requests: M.C. Sharma, MD, Assistant Professor, Department of Pathology, All India Institute of Medical Sciences, New Delhi-110029, India. Phone: 91 11 2659 3371; fax: 91-11-2658-864 e-mail: firstname.lastname@example.org
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|Title Annotation:||Original Article|
|Author:||Sharma, Mehar Chand|
|Publication:||Ear, Nose and Throat Journal|
|Date:||Aug 1, 2003|
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