An unusual oral manifestation of type 1 neurofibromatosis: A case report and review of literature.

Neurofibroma is a benign peripheral nerve sheath tumor and is the most frequent tumor of neural origin. Its presence is one of the clinical criteria for the diagnosis of neurofibromatosis type 1 (NF1; a common hereditary disease occurring in one out of every 3000 births). The diagnosis can sometimes be made at birth, while in others the diagnosis is made later in life after the appearance of additional clinical criteria. Majority of the solitary neurofibromas are sporadic, while a few are associated with NF1 syndrome. Oral hard and soft tissue are affected by the tumor; however, the tongue is the most affected site. Gingival neurofibroma is an uncommon oral manifestation of NF. Here, we report a rare case of gingival neurofibroma in NF1 patient. One of the most feared complications of NF1 is its transformation into neurofibrosarcoma, which bears a very poor prognosis. Treatment of neurofibroma is surgical resection.

INTRODUCTION

Neurofibroma is a benign peripheral nerve sheath tumor[12345] arising from the Schwann cells and perineural fibroblasts. They may appear in patients with or without hereditary neurofibromatosis (NF). Oral involvement is noted in 3.4-92% of adults and 40% of children with NF1.[6] Seven clinical forms of NF are described [Table 1].[7]

Table 1

Clinical forms of NF

CASE REPORT

A 28-year-old male patient reported [Figure 1] with the chief complaint of a painless swelling in the right upper back tooth region since 3 years. History revealed swelling was of insidious in onset, which increased to attain the present size. Family history revealed the patient's father [Figure 3] also had multiple swellings all over the body and face. On general examination, multiple swellings all over the trunk region and arms were observed [Figure 2]. Solitary well-defined oval shaped swelling [firm in consistency and nontender on palpation Figure 4] approximately 4 cm × 3 cm was present in the right maxillary posterior region extending from distal aspect of maxillary first premolar to mesial aspect of third molar. Radiographic screening was normal. However, multiple, discrete, sessile cutaneous masses which had started appearing since childhood were observed. Histopathological examination of incisional biopsy of the oral lesion showed spindle cells with elongated wavy nuclei. The lesional area was separated from the overlying epithelium by mature fibrous connective tissue [Figure 5].

Figure 1

Patient with cutaneous neurofibroma

Figure 3

Patient's father with cutaneous neurofibroma

Figure 2

Cutaneous neurofibroma over the trunk

Figure 4

Gingival neurofibroma

Figure 5

H and E stained section of the lesion under, ×40

DISCUSSION

Neurofibromatosis type 1 is due to alteration of NF1 gene, which is a tumor suppressor gene located in the long arm of chromosome 17. The clinical criterion for the diagnosis of NF1 encompasses presence of six or more Café’au lait spots (>5 mm in children or >15 mm in adults), two or more cutaneous or subcutaneous neurofibromas or one plexiform neurofibroma, freckles in the axilla or groin optic glioma, two or more lisch nodules (pigmented hamartomas of the iris), bony lesion with sphenoid wing dysplasia or bowing of the long bones with or without pseudoarthrosis, and/or first degree relative with NF1. Our case satisfied two criterions. Other features that have been described to occur variably in individuals with NF1 include short stature, large head size, failure to gain weight, precocious puberty, vascular disease including childhood hypertension, neural problems secondary to the spinal cord involvement, headaches, cognitive problems, stroke, brain tumors, and rarely tumors such as pheochromocytoma, and juvenile chronic myeloid leukemia.

Common sites of the oral solitary neurofibromas include tongue (26%), buccal mucosa (8%), alveolar ridge (2%), labial mucosa (8%), palate (8%), gingiva (2%), nasopharynx, paranasal sinuses, larynx, floor of the mouth and salivary gland. Tumors may also arise within the bone.[8] This patient reported with gingival localization of neurofibroma, which is extremely rare and unique. Gingival neurofibromas can cause periodontal disease, as tissue growth is an obstacle in carrying out routine oral hygiene measures. They can also cause tooth malposition and impaction. Oral radiographic findings unique to NF include lengthening, narrowing and rarefaction of coronoid and articular process, deepening of sigmoid notch, an enlarged mandibular canal, mandibular foramen and mental foramen. Other findings are shortening of the ramus, notching of the inferior border of the mandible.[9] In the case reported here, no radiologic alterations were observed. Oral neurofibromas are most frequently treated by surgical excision. Usually, the prognosis for solitary neurofibroma is extremely good, with only rare instances of recurrence. The present case was kept under observation and was recalled every 3 months for a period of 1 year and showed no signs of recurrence. Malignant transformation of neurofibromas with NF1 into neurogenic sarcomas bears a very bad prognosis with a 5 years survival rate of just 15%.[10] Long-term review of patients and genetic counseling is recommended owing to the likelihood (50%) of vertical transmission.[11] NF1 is a commonly encountered neurocutaneous disorder. It is imperative for the general physicians and dermatologists to be aware of the oral manifestations of NF1 considering the risk of malignant transformation and the poor prognosis.