|Year : 2015 | Volume
| Issue : 1 | Page : 33-36
Solitary cellular neurofibroma of alveolar mucosa unassociated with neurofibromatosis-1
Laxmidevi B Lankesh1, KR Ashok Kumar2
1 Department of Oral Pathology and Microbiology, Sri Siddhartha Dental College and Hospital, Tumkur, Karnataka, India
2 Department of Oral and Maxillofacial Surgery, Sri Siddhartha Dental College and Hospital, Tumkur, Karnataka, India
|Date of Web Publication||20-May-2015|
Dr. Laxmidevi B Lankesh
Department of Oral Pathology and Microbiology, Sri Siddhartha Dental College, B. H. Road, Agalakote, Tumkur - 572 107, Karnataka
Source of Support: None, Conflict of Interest: None
Neurofibromas (NFs) are rare neurogenic tumors of the oral cavity. They can present as solitary, or multiple when associated with neurofibromatosis-1 (NF-1)/von Recklinghausen's disease. Solitary intraoral NFs unassociated with NF-1 are sporadic and mimic any other soft tissue tumors of the oral cavity. Hence, final diagnosis can only be rendered after histopathological examination although they exhibit numerous microscopic variants. They show numerous mast cells and immunopositive for S-100 protein. Here, we are presenting one such case of NF in a 55-year-old male patient.
Keywords: Alveolar mucosa, cellular neurofibroma, mast cells, neurofibromatosis-1, S-100, solitary neurofibroma
|How to cite this article:|
Lankesh LB, Ashok Kumar K R. Solitary cellular neurofibroma of alveolar mucosa unassociated with neurofibromatosis-1. J Orofac Sci 2015;7:33-6
|How to cite this URL:|
Lankesh LB, Ashok Kumar K R. Solitary cellular neurofibroma of alveolar mucosa unassociated with neurofibromatosis-1. J Orofac Sci [serial online] 2015 [cited 2019 Dec 6];7:33-6. Available from: http://www.jofs.in/text.asp?2015/7/1/33/157374
| Introduction|| |
The peripheral nerve sheath tumors are neuroectodermal in origin, in which benign category consists of schwannoma and neurofibroma (NF), and malignant include malignant peripheral nerve sheath tumor (MPNST), neurofibrosarcoma, etc. Although they share common neural origin, however they represent clinical and microscopic heterogeneity. 
The majority of solitary NFs are sporadic. They appear as soft tissue growths when smaller peripheral nerves are involved. , Histopathology of solitary and multiple NFs are essentially identical, although the malignant transformation of multiple NF into neurogenic sarcomas is seen in 5-15% of patients with neurofibromatosis-1 (NF-1). 
Histologically NFs consists of a mixture of Schwann cells, perineurial cells, and endoneurial fibroblasts. Based on morphological features they are classified into major and minor variants. Major variants include plexiform, diffuse, and pacinian NFs, while minor variants include epithelioid, cellular, myxoid, glandular, xanthomatized, pigmented, dendritic NFs. ,
Some of these histopathologic variants are rarely discussed in the literature. Hence, we report a case of NF of cellular variant that shows increased cellular density, which would raise the concern to differentiate it from malignant peripheral nerve tissue tumor.
| Case Report|| |
A 55-year-old male patient reported to our hospital with a complaint of mass in the lower right back region of the jaw present since 2 years. It started as a small swelling and gradually increased to the present size and was asymptomatic, but created disturbance in mastication and tongue movements, which made the patient to seek the treatment. His general physical examination and family history were noncontributory.
Intra-oral examination revealed solitary pinkish red pedunculated mass, with a smooth surface on the edentulous ridge of right posterior mandibular region measuring around 5 cm × 4 cm × 5 cm in size. It was mobile, firm, nontender on palpation [Figure 1]. Panoramic radiograph was noncontributory with no evidence of any lytic bone changes, and or cortical bone erosion of the mandible [Figure 2]. Clinical diagnosis of pyogenic granuloma was made. The lesion was excised under local anesthesia and sent for histopathological examination.
|Figure 1: Preoperative view: Pinkish red, pedunculated mass, with smooth surface on the edentulous ridge of right posterior mandibular region|
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|Figure 2: Panoramic radiograph showing no lytic changes in the bone on the right side of the mandible|
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Macroscopically the lesion appeared as pinkish red mass, with a smooth surface and regular borders, firm in consistency [Figure 3].
Microscopically revealed well circumscribed, but unencapsulated lesion, lined by stratified squamous parakeratinized epithelium showing surface ulceration. The connective tissue showed proliferating numerous spindle cells with delicate wavy nuclei in storiform-like pattern. Few areas showed palisaded arrangement of cells resembling Antoni A areas of schwannoma, but no verocay bodies. Delicate interwining fibrils and fibroblasts were seen along with infiltration of lymphocytes and few neutrophils [Figure 4]. However, increased cellular density made to reveal the fields thoroughly to eliminate the malignant features. As the features of malignancy were absent, with presence of numerous mast cells [Figure 5] and S-100 protein positivity [Figure 6] the diagnosis of NF was made whilst the increased cellular density suggested the cellular variant of NF. Follow-up of 1-year revealed no recurrence of the lesion.
|Figure 4: Photomicrograph showing the proliferation of delicate spindle cells of thin wavy nuclei with interwining delicate connective tissue fibers (H and E, ×40)|
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|Figure 5: Photomicrograph showing the metachromatic staining of mast cells (Toluidine blue, ×100)|
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|Figure 6: Photomicrograph showing S-100 positive cells (S-100 staining, ×400)|
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| Discussion|| |
Neurofibromas are the hallmark of NF-1. Approximately 25% of all NFs are found in the head and neck region and 6.5% occur in the oral cavity as solitary or multiple lesions associated with NF-1.  The extremely wide range of manifestations of this neurocutaneous syndrome was first described by von Recklinghausen in 1882 with an incidence of 1 in 3,000 individuals, showing the features such as multiple NFs, skin pigmentation (cafe-au-lait spots) and bony abnormalities with an increased incidence of phaeochromocytoma.  The sporadic cases occur spontaneously without any of these manifestations, and they are usually solitary.
Solitary sporadic NFs of head and neck region are more commonly seen in the tongue, followed by buccal mucosa, gingiva, less common being the alveolar mucosa, labial mucosa, palate, floor of the mouth and rarely intraosseous. ,, Average age of the patient is approximately 45 years, usually presenting with an uninflamed, slowly enlarging, asymptomatic lesion that varies greatly in size from tiny nodules to large pedunculus masses. Hence mimic any other common soft tissue tumors of the oral cavity such as papillomas, pyogenic granulomas, fibrous hyperplasias, peripheral ossifying fibroma etc. In our case, it was diagnosed as pyogenic granuloma and excised. Hence, the definitive diagnosis can only be rendered after histopathological examination.
Although NF exhibits several microscopic variants, classic type being the most common one, and others include collagenous, cellular, myxoid, pigmented, lipomatous, epitheloid, glandular, dendritic cell NFs that are categorized depending on the content of the lesion. ,, In comparison to classic or conventional NF, cellular variant exhibits highly cellular areas of Schwann cells set in a uniform collagen matrix devoid of mucosubstances. The cells are arranged in short fascicles, whorls or even in storiform pattern with absence of elevated mitotic activity and nuclear atypia. ,
The most common differential diagnosis of NF in benign category is schwannoma which is an another neuroectodermal tumor. However, it can be easily differentiated as the latter has Antoni A and B areas with verocay bodies and encapsulation. However in cellular variant of NF few areas resemble Antoni A type of arrangement of cells thus becomes difficult to distinguish both the lesions. While careful evaluation in such case may reveal lack of clear partition of Antoni A and B zones, with absence of verocay bodies and lack of encapsulation in NF, which can eliminate possibility, along with immunohistochemistry of S-100 protein where it shows 100% positivity in schwannoma as compared to NF with only 30-50%. , Thus in our case, schwannoma was eliminated.
The increased cell density of cellular NFs even alarms to distinguish it from low grade MPNST, which is an another important differential diagnosis to be considered. Careful evaluation of histopatholgical features is necessary to eliminate, such as remarkable cytological atypia, increased mitotic activity, and necrosis, which are usually absent in cellular NF. The recognition of these atypical features are of great importance to pathologists as these cases masquerade both histologically and cytologically its malignant counterpart. 
The present case was unencapsulated, highly cellular spindle cell tumor, with no distinct two patterns, verocay bodies, cellular atypia and mitotic figures were identified. Toluidine blue staining showed the mast cells. S-100 was patchy positive. All these features were compatible with the diagnosis of cellular NF.
To our knowledge cellular NF of the oral cavity, have rarely been documented. At the same time meticulous diagnosis of this variant is essential, as differences in treatment and clinical behavior between benignancy and malignancy. Excision with preservation of the nerve is preferred for solitary cellular NFs, having good prognosis, with rare instances of local recurrence.
| Acknowledgments|| |
We would like to thank Dr. Jyothi Mahadesh Professor and HOD, Department of Oral Pathology and Microbiology, Sri Siddhartha Dental College and Hospital, for all her support and help.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]