Malignant peripheral nerve sheath tumors of the oral cavity. Review of the literature and report of a case

Malignant peripheral nerve sheath tumour of the oral and maxillofacial region-A systematic review

To integrate the available data published on malignant peripheral nerve sheath tumours (MPNST) of the oral and maxillofacial region. Searches in Embase, PubMed, Web of Science and Scopus were conducted for the identification of case reports/case series in English language. The risk of bias was assessed using the Joanna Briggs Institute tool. Outcomes were evaluated by Cox regression and Kaplan-Meier methods. A total of 306 articles were retrieved, 50 of which reporting 57 MPNST were included. The lesion showed a predilection for the mandible (n = 18/31.57%) of middle-aged adults (~40.5 years) with a male/female ratio of 1.1:1. The individuals were mostly symptomatic with a mean evolution time of 9.6 months. Surgical removal plus adjuvant therapy (especially radiotherapy) was the main approach (51.86%). Recurrence was reported in 39.62% of cases. Nodal and distant metastases were identified in 28.26% and 26.66% of cases, respectively. The 2-year cumulative survival rate was 55%. Independent predictors of poor survival were the presence of neurofibromatosis type 1 (p = 0.04) and distant metastases (p = 0.004). The diagnosis of MPNST is challenging due to the variety of its clinical and histopathological presentations. Local aggressiveness and the potential for metastases are common outcomes of this neoplasm.

Comprehensive Analyses of Intraoral Benign and Malignant Nerve Sheath Tumors: The Rare Disease Entities Revisited

INTRODUCTION

Intraoral benign and malignant nerve sheath tumors (BNST and MNST) are rare tumors with non-specific clinical presentations and represent diagnostic and therapeutic challenges. Current knowledge regarding their demographic, clinicopathological features and treatments remains fragmented.

MATERIALS AND METHODS

The original data about patients diagnosed as intraoral BNST and MNST were retrieved from our disease registry (2005-2017). Comprehensive reviews of English and Chinese literature were performed to collect and analyze the epidemiological, clinicopathological data and treatment outcomes about those published cases.

RESULTS

Thirty-four intraoral BNSTs were found at our institution in the past 13 years. Literature reviews identified 354 intraoral BNSTs in 223 articles and 60 intraoral MNSTs in 50 articles. Most intraoral BNSTs and MNSTs were presented in the second to fifth decade of life. Males outnumbered females in MNSTs, while BNSTs displayed a slight female preponderance. The common sites for intraoral BNSTs were parapharyngeal space followed by tongue, whereas mandible was the most common site for MNSTs. Most intraoral BNSTs were presented as slow-growing, painless mass or swelling, while MNSTs usually appeared as painful and invasive mass with discomfort. Surgical excision was preferred for intraoral BNSTs with excellent prognosis. Complete resection was indicated for intraoral MNST with dismal prognosis as evidenced by much recurrence, metastasis, and death.

CONCLUSION

Intraoral BNST and MNST are rare diseases which should not be ignored when intraoral painless or painful mass/swelling is found. Surgical excision is indicated for intraoral BNST with favorable outcomes. However, further investigations are warranted to optimize the treatment for intraoral MNST to improve its prognosis.

Malignant melanotic schwannoma of the oral cavity

Intraoral malignant melanotic schwannoma is an extremely rare tumor. Two cases are presented, one occurring in the mandible of a 62-year-old man, the other in the maxilla of a 79-year-old man. The clinical presentation, light microscopic findings and immunohistopathological features are described. The difficulty of diagnosing this special tumor at initial presentation correctly, is discussed.

Neoplasms metastatic to the mouth, jaws and surrounding tissues

5% of all malignancies involve the oral cavity. One percent of these malignancies are secondary to neoplasms that are usually found below the level of the clavicles. As it is widely accepted that the jaws do not contain a lymphatic system, it is believed that metastases there occur via the blood stream, a fact that is supported by the occurrence of metastatic foci in areas where spongiosa and slowing of the circulation favour the entrapment of metastatic emboli. This however does not explain why most of the metastases occur in the lower jaw (and in particular in the premolar-molar area) and not in the maxilla, where the spongiosa is more abundant. Batson's plexus has also been mentioned as a possible route of metastasis to the head and neck, thus explaining why, in some cases of metastases, the lungs are not involved, as the blood has not been filtered through the pulmonary bed before reaching the head and neck. In our review of the literature we found 422 metastatic lesions in the mouth, jaws and the surrounding tissues in 365 patients equally divided between men and women. 56.5% of the cases were above the age of 50. In 228 cases there were other metastases as well, whereas in 114 cases the only metastasis found was the one under study. In 22% of the cases, the metastatic focus in our area was the first indication of the existence of an undiagnosed primary malignant tumour somewhere else.(ABSTRACT TRUNCATED AT 250 WORDS)

Malignant schwannoma of the mandible

A case of malignant schwannoma occurring in the mandible of a 76-year-old Japanese woman is presented. Results of the gross examination are described as well as the surgical procedure. Details of the staining techniques for examination of the biopsy specimen are given. The histopathological findings are mentioned including those obtained from radiographic, microscopic, and electron microscopic examination. A discussion of the disease and of its difficulty of diagnosis follows.

Fibrosarcoma of the mandible

Fibrosarcoma is a rare malignancy in the oral cavity. Tumours of fibrous connective tissue are sometimes difficult to classify as benign or malignant. The literature is reviewed and three cases of oral fibrosarcoma are presented.

Malignant Schwannoma of cranial nerves

The clinical presentation and histopathological features of 5 cases of malignant Schwannoma of cranial nerves are described. The ultrastructural appearances of one case and the pattern of nerve sheath cell differentiation of these tumours are also discussed. These uncommon tumours often are not diagnosed at initial presentation. Since the cases provide evidence that early diagnosis and surgical treatment are vital in the management of patients with this tumour criteria for its diagnosis are suggested.

[Neurogenic sarcoma of the head and neck with contact to the skull base (author's transl)]

The neurogenic sarcoma is a neoplasm found seldom. It descends from the sheaths of peripheric nerves. If this tumor develops from a solitary or multiple neurofibroma, it might also be called a neurofibrosarcoma. All other synonyms, especially that of the malignant schwannoma, should better be abandoned for histogenetic reasons. Today the classification of all tumors of the peripheral nervous system is based on a suggestion of the WHO from 1969. The tabular summary of the literature shows that only a little more than a hundred cases of neurogenic sarcoma of the head and neck were reported during the last 50 years. Differential diagnosis of this malignant tumor includes nearly all other malignant neoplasms of soft tissue, sometimes even anaplastic carcinoma. Histopathology, including electron microscopy, is described in general and also in detail with regard to three cases. Three forms of micro-morphological variants are dealt with, too. For diagnosis histological examination will be absolutely successful only in cases of neurofibromatosis or in cases where the nerve from which the tumor originates may be identified. Otherwise, conventional and computerized X-ray tomography may be helpful. Finally, some therapeutic and prognostic principles are discussed.

Neural tumors of the oral cavity. A review of the spectrum of benign and malignant oral tumors of the oral cavity and jaws

The clinical and histologic features of benign and malignant neural tumors of the oral cavity and jaws are reviewed. Some rarer histologic variants are mentioned. Particular attention is paid to the two syndromes involving neural tumors of the oral cavity, namely, neurofibromatosis and multiple endocrine neoplasia III. A previously unreported case of the latter is presented.