Intraoral schwannoma: a case report

Schwannoma of the Lower Lip: A Case Report of an Unusual Presentation

Schwannoma is a benign neoplasm that originates from the neural sheath of Schwann cells. Although extracranial schwannomas are commonly observed in the head and neck region, only 1% are found in the intraoral cavity. This article describes the first case in the Eastern Mediterranean region of a lower lip schwannoma in a 17-year-old male patient.

Primary intra-osseous Hybrid Schwannoma-Perineurioma in the mandible

Benign nerve sheath tumours include perineuriomas, schwannomas and neurofibromas. Hybrid schwannoma-perineurioma represents a cutaneous, subcutaneous or occasionally intra-osseous tumour with schwannian cytomorphology and perineurioma-like architecture consisting of a mixture of both types of cells. These tumours can develop at any age and there is no gender-predilection. Tongue is the most frequently affected site, followed by palate, mouth floor, jugal mucosa, lips and, more rarely, mandible. We present a case of hybrid tumour with schwannoma-perineurioma morphology located on the right mandibular body (intra-osseous) of a 54-year-old female patient. The tumour was symptomatic and evolving for six months. Microscopically, it was encapsulated and highly cellularised, presenting fascicular aspect and exhibiting scant mitotic activity. The tumour consisted of distinct cellular populations involving fusiform cells, cells with wavy and hyperchromatic nucleus or even epithelioid cells. Positive immunostaining for S-100 and epithelial membrane antigen (EMA) was observed. The lesion was completely removed under general anaesthesia, with the patient showing no clinical or radiographic sign of relapse after two-year follow-up. Despite the limited knowledge on the pathogenesis of Hybrid Schwannoma-Perineurioma, these tumours seem to present a non-aggressive biological behaviour. Conservative surgery provides adequate solution without recurrence, even after a long-term follow-up. Key words:Nerve sheath tumours, Schwannoma, Perineurioma, Immunohistochemistry.

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.

Clinical features and management of schwannoma affecting the upper and lower lips

Head and neck schwannomas comprise 25-40% of all schwannomas, with presentation on the lips as the rarest and most surgically complicated site for perioral tumors. A systematic literature review was conducted to include 21 cases of patients with schwannoma of the upper or lower lips. The majority of patients presented with a single, painless, well-encapsulated nodule on the upper or lower lips. The nodules were consistently slow-growing, with an average 29.3 months from symptom onset to clinical presentation. Most cases were complicated by profound cosmetic disfigurement as well as dysphagia, dysarthria, snoring, and/or sleep apnea. Overall, histological analysis was consistent with classic schwannoma, and all cases were treated via complete surgical excision, and for malignant tumors, additional therapy was utilized. All but four cases achieved full remission by final follow-up. Recurrence rate for benign lip schwannomas was 5.3%, which is remarkably different from the standard recurrence rate of 8-24% for benign peripheral schwannomas. Additionally, the proportion of malignant tumors was greater for lip schwannomas than other schwannomas. Lip schwannomas demonstrate different characteristics than schwannomas from other locations on the body, and these remarkable differences highlight significant implications for clinical practice. Complete excision is the primary mode of treatment with overall excellent postoperative prognosis and rare instances of recurrence. Given the rarity of this tumor, this review of available cases serves to comprehensively describe clinical presentation and surgical treatment approaches to upper and lower lip schwannomas.

A Lip Lump: An Unexpected Histological Diagnosis of a Lip Schwannoma

Schwannomas are benign nerve sheath tumours arising from Schwann cells. They comprise 1% of all benign tumours. In the 2016 World Health Organisation Classification of Central Nervous System, they are classified as a tumour of the cranial and paraspinal nerves, Schwannoma 9560/0. A 23-year-old Caucasian lady presented with a seven-month history of a painless right upper lip lump. Examination revealed a small cystic 0.5 cm diameter lesion within the right upper lip. The clinical impression was that of a mucocele. Excision of the lip lesion was performed under local anaesthetic. Histological examination of the excised lesion demonstrated a circumscribed nodule consisting of spindle cells mixed with vascular spaces containing red blood cells and fibrin. Immunohistochemistry for S100 was strongly positive. The findings were consistent with that of a small benign schwannoma. The current consensus is for surgical excision of a conservative nature with no need for margins. If recurrence does occur one needs to consider whether complete enucleation was achieved or whether malignant transformation has occurred.