Report of Four Cases of Intraoral Lipomatous Neurofibroma

Introduction

Neurofibroma is a benign tumor that originates from the peripheral nerve sheath. In its localized form, the tumor most often presents as a superficial, solitary lesion arising anywhere on the body. Oral localized neurofibromas are common. The diffuse and plexiform growth patterns of neurofibroma are associated with neurofibromatosis 1, while the localized form is not. Histologically, neurofibromas are widely variable. One rare form is the lipomatous neurofibroma. This more recently described variant is characterized by the presence of intratumoral fat in clear excess of entrapped adipose tissue. Typically, this variant is cutaneous and affects the head and neck- only a handful of cases have been reported in the oral cavity. Here, we report four cases of intraoral lipomatous neurofibromas.

Materials and Methods

Cases for this series were retrieved from the archives of Oral Pathology Laboratory, Inc.

Results

Four cases were identified, two of which our laboratory have previously presented. Age at presentation ranged from 18 to 62 with a median of 35. Two male patients and two female patients were affected, with three of the tumors presenting on the hard palate and one presenting on the dorsal tongue. All tumors presented as a raised mass. No patients had a history of neurofibromatosis type 1. Immunohistochemical studies completed on the cases reveal S100 positivity, and negativity for CD99, CD34, and BCL2. Clinically, these tumors were often biopsied under suspicion of a salivary gland neoplasm.

Conclusion

Five cases of intraoral lipomatous neurofibroma have been reported to date- one by Shimoyama et al. and the four present cases. The histologic features identified here are concordant with previously described cases, both intraoral and cutaneous. This case series expands the known spectrum of this lesion. Greater recognition of this variant may help to identify the driving forces behind this histopathologic finding.