Intraosseous intraneural perineurioma derived from the inferior alveolar nerve with an abnormality of chromosome 22 and expression of the BCR-ABL fusion gene: report of a case and review of recent literature

Abstract

Background: Perineurioma (PN) is a peripheral nerve disease that primarily develops in the limbs and trunk and very rarely occurs in the oral cavity. PN is classified into two types: intraneural perineurioma (INPN) and soft tissue perineurioma (extraneural perineurioma, ENPN). In this article, we report a patient with mandibular body INPN derived from the perineurium of the inferior alveolar nerve.

Case presentation: The patient was a 43-year-old male. He consulted our department for a detailed examination of the right mandibular body. A biopsy was performed at another hospital and he was diagnosed with a schwannoma. At his first visit, hypesthesia extending from the right lower lip to the mental region was recognized and enlargement of the right mandibular canal was confirmed with X-ray CT and MRI. Considering the possibility of future tumor growth, we extirpated the tumor under general anesthesia. Cystic tumor was seen continuously in the inferior alveolar nerve. Immunohistologically, the tumor cells were positive for Glut-1, weakly positive for EMA, and weakly positive for Claudin-1, and the histopathological diagnosis was INPN. In addition, absence of the BCR region of chromosome 22 and expression of the BCR-ABL fusion gene were observed by fluorescent in situ hybridization (FISH), and a chromosome 22 abnormality was confirmed. These findings indicated that the disease was a neoplastic lesion.

Conclusion: Expression of the BCR-ABL fusion gene in INPN that develops in the oral cavity is thought to be very rare, and to the best of our knowledge, ours is the first case to be reported in the literature. About three postoperative years have passed, but findings suggestive of recurrence have not been observed.

Keywords: BCR-ABL fusion gene; Chromosome 22 abnormality; ENPN; INPN; Perineurioma.

Fig. 1

Intraoral findings. Although no obvious neoplastic lesions were observed, hypesthesia extending from the right lower lip to the mental region was noted

Fig. 2

X-ray findings. a X-ray CT finding (panoramic image). A radiolucent finding of a similar circle was recognized in the right mandible body (yellow arrow). b X-ray CT finding (coronal image). We confirmed the enlargement of the right mandible canal. The destruction of the mandibular canal wall is not clear (yellow arrow)

Fig. 3

MRI findings. a Horizontal section. An irregular high signal in the STIR image was recognized (yellow arrow). b Sagittal sections. Dilation of the right mandibular canal was observed around the mandibular foramen (yellow arrow). c Dynamic images showed crescendo enhancement

Fig. 4

a Intraoperative findings. A cystic tumor of 3.2 × 1.0 cm was observed macroscopically following the inferior alveolar nerve. b Extirpation of tumor findings. The surrounding inferior alveolar neurovascular bundle was ligated and cut and removed as a lump. c, d Postoperative panoramic X-ray and X-ray CT findings. The radiopacity of the excised cavity was enhanced, and hyperostosis was confirmed

Fig. 5

H-E staining. a Weak expansion. A tumor was found in the inferior alveolar nerve and inside (black arrow). b × 100. A thickened perineurium cell layer was confirmed (yellow arrow). c × 200. A part showing a pseudo-onion bulb-like structure confirming proliferation of tumor cells was observed so as to separate the nerve fiber bundle. B and C in Fig. 5a are enlargements of the same part as Fig. 5b, c

Fig. 6

Immunohistochemical staining. The tumor cells were Glut-1 positive (d, e), weakly positive EMA (b), and Claudin-1 weakly positive (c). S-100 was negative for tumor cells (a), but positive for nerve fibers

Fig. 7

Expression rate of MIB-1 (Ki-67). The expression rate (%) of MIB-1 in INPN was 1.6% (positive nucleus: yellow arrow)

Fig. 8

FISH (fluorescent in situ hybridization) method. a The BCR-ABL fusion gene shows a yellow signal. A yellow signal was observed, and expression of BCR-ABL fusion gene was confirmed (white arrow). b An orange signal indicates ABL gene and a green signal indicates BCR gene. Cells with one green signal of BCR gene were observed, and lack of BCR region was confirmed (white arrow)