Intraoral Pseudo-Onion Bulb Intraneural Proliferations in a Patient with Hemimandibular Hyperplasia: A Case Report and Review of the Literature

Abstract

This report and review of the literature describes a case of benign intraoral lesions of perineurial origin in a patient with symptomatic hemimandibular hyperplasia causing partial denture soreness. Perineuriomas are a benign peripheral nerve sheath tumor composed of perineurial cells. Intraoral perineuriomas are an extremely rare entity. Two main types of perineuriomas have been described: intraneural and extraneural perineuriomas. A third, similar entity, called an intraneural pseudoperineuriomatous proliferation, has recently been proposed in the literature as a separate and distinctive diagnosis. This report describes the histologic and clinical presentation of intraneural pseudoperineuriomatous proliferations in a patient with hemimandibular hyperplasia.

Keywords: Fluorescence in situ hybridization; Hemimandibular hyperplasia; Immunohistochemistry; Intraneural pseudoperineuriomatous proliferation; Oral pathology; Perineurioma.

Fig. 1

The patient presented with striking facial asymmetry resulting from right hemimandibular hyperplasia

Fig. 2

Multiple fibrotic, warty lesions are seen over the right tongue (a) and right anterior mandibular alveolus (b)

Fig. 3

Panoramic radiograph showing the enlarged right mandible distal to the symphysis, along with the enlarged right mandibular canal and right condyle

Fig. 4

Axial CT, bone window (a) and coronal CT, bone window (b) showing the markedly enlarged right mandibular condyle

Fig. 5

3D CT reconstruction showing the enlarged right mandible with areas of bony proliferation

Fig. 6

Islands of pseudo-onion bulbs seen in a collagenous stroma (H&E ×10)

Fig. 7

EMA highlights the concentric layers of proliferating perineurium (×20)

Fig. 8

S-100 highlights the residual Schwann cells but is negative in tumoral cells (×20)

Fig. 9

Dual-color fluorescence in situ hybridization probe negative for NF2 deletion. A normal copy number shows two red NF2 signals and two green chromosome 22 centromeric probes. Only individual and well-delineated cells were scored. Overlapping cells were excluded from the analysis. Hemizygous deletion in NF2 would show one red and two green signals

Fig. 10

A lateral cephalometric radiograph showing the alloplastic TMJ (a). Cropped panoramic radiograph showing the dental implants following mandibular extractions (b)