Solitary Giant Neurofibroma of the Mental Nerve: A Trauma-Related Lesion?

Revisiting the NPcis mouse model: A new tool to model plexiform neurofibroma

Neurofibromatosis Type I (NF1) is a rare genetic disorder. NF1 patients frequently develop a benign tumor in peripheral nerve plexuses called plexiform neurofibroma. In the past two decades, tissue-specific Nf1 knockout mouse models were developed using commercially available tissue-specific Cre recombinase and the Nf1 flox mice to mimic neurofibroma development. However, these models develop para-spinal neurofibroma, recapitulating a rare type of neurofibroma found in NF1 patients. The NPcis mouse model developed a malignant version of neurofibroma called malignant peripheral nerve sheath tumor (MPNST) within 3 to 6 months but intriguingly without apparent benign precursor lesion. Here, we revisited the NPcis model and discovered that about 20% display clinical signs similar to Nf1 tissue-specific knockout mice models. However, a systematic histological analysis could not explain the clinical signs we observed although we noticed lesions reminiscent of a neurofibroma in a peripheral nerve, a cutaneous neurofibroma, and para-spinal neurofibroma on rare occasions in NPcis mice. We also observed that 10% of the mice developed a malignant peripheral nerve sheath tumor (MPNST) spontaneously, coinciding with their earring tag identification. Strikingly, half of the sciatic nerves from NPcis mice developed plexiform neurofibroma within 1-6 months when intentionally injured. Thus, we provided a procedure to turn the widely used NPcis sarcoma model into a model recapitulating plexiform neurofibroma.

Solitary neurofibroma of the floor of the mouth: rare localization at lingual nerve with intraoral excision

Background

Neurofibromas (NF) are benign tumors of the peripheral nerves that are composed of Schwann cells, perineural-like cells and fibroblasts. The differential diagnosis for a solitary intraneural variant of neurofibroma arising in the floor of the mouth is broad and includes a submandibular gland neoplasm and adenopathy, among others. The intraoral approach is the best choice for a medium-sized lesion.

Case presentation

We report a rare case of a solitary neurofibroma of the floor of the mouth in a 31-year-old male. The patient consulted the dental emergency department for acute pain of the left mandible. Systematic clinical examination revealed the presence of a mass in the left mouth floor. The panoramic x-ray was not conclusive and the magnetic resonance imaging (MRI) revealed a well-defined soft tissue lesion with homogenous isosignal intensity on the T1-weighted image, high intensity signal on the T2-weighted image and heterogeneous enhancement following contrast-enhancement on the T1-weighted Fast Sat image. The surgical excision of the soft-tissue neoplasm was accomplished by an intraoral approach. The specimen was sent for histopathologic analysis and Immunohistochemical studies which confirmed the diagnosis of a myxoid predominant intraneural solitary neurofibroma.

Conclusion

The diagnosis of neurofibroma was confirmed by histopathological evaluation and immunohistochemical studies which also excluded other entities in the histopathologic differential diagnosis including schwannoma and a malignant peripheral nerve sheath tumor among other. Localized (solitary) neurofibromas most often occur as sporadic lesions, however; diagnosis of a solitary neurofibroma prompts clinical evaluation to exclude the remote possibility of neurofibromatosis. The purpose of this case report is to raise awareness of the uncommon presentation of neurofibroma and to document the successful management of such a lesion using an intraoral approach.

Trigeminal neurofibroma in the infratemporal fossa arising from the inferior alveolar nerve: A case report

Solitary neurofibromas arising from cranial nerves are rare, and those arising from the peripheral divisions of the trigeminal nerve are even rarer. Although infratemporal fossa (ITF) masses are challenging to remove, certain approaches are considered feasible for this region. The present study reports a rare case of an ITF neurofibroma arising from the inferior alveolar nerve. The 27-year-old male patient presented with numbness of the right jaw. A radiological examination revealed a large mass occupying the ITF, from the mandible to the foramen ovale, originating from the inferior alveolar nerve in the mandible. The tumor was successfully excised via a transtemporal approach followed by a transoral-retromolar approach. A histological examination confirmed the diagnosis of neurofibroma. The present case demonstrates that a combination of the transtemporal and transoral-retromolar approaches may provide wide access to the ITF region.

Removal of solitary neurofibroma of the external nose by intranasal approach

INTRODUCTION

Solitary neurofibroma originating from the external nose is extremely rare, and to our knowledge, only 3 cases have been reported so far in English literatures. It may originate from the ophthalmic (V1) and maxillary (V2) branches of the trigeminal nerve.

CASE REPORT

We present a rare case of solitary neurofibroma arising from the external nose, which was successfully removed by intranasal approach with intercartilaginous incision.

CONCLUSION

This case emphasizes two important points. First, we should keep in mind that this clinical entity is included in the differential diagnosis of soft tissue masses arising from the external nose. Second, we should choose the best surgical approach for complete removal with the maintenance of cosmetic appearance.

An unusual presentation of neurofibroma masquerading as a vascular hamartoma, post-iatrogenic intervention

Neurofibroma is a localized discrete mass of benign nerve sheath tumour in the peripheral nervous system. Mostly present as skin lesions. Solitary neurofibroma may occur in deep soft tissue or subcutaneous plane in rare cases associated with syndromes like NF1. The neurofibroma most commonly present as skin lesions as isolated soft papules or nodules arising in any cutaneous site. Present case depicts unusual presentation of a neurofibroma as a vascular hamartoma post an iatrogenic intervention.