Intramucosal melanotic nevi - A case report of an unusual gingival enlargement.

Intramucosal melanotic nevus with multiple polypoid presentations in oral cavity is rare; though single nevus is not uncommon. Nevi are benign proliferations of nevus cells either in the epithelium or in the subepithelial stroma. They are best categorized as hamartomas rather than true neoplasm. We present a case of intramucosal melanotic nevi in a 26-year-old male patient, which clinically resembled hereditary fibrous gingival enlargement.

INTRODUCTION

Intramucosal melanotic nevi with multiple polypoid presentation in oral cavity are rare though solitary nevi are not uncommon.[1]

In 1943, Ackermann and Field have reported the first documented case of an oral Nevus.[2]

Comerford et al., were the first to propose the term Intralamina propia Nevus.[3] King et al., 1967 adopted the less anatomically specific term, Intramucosal nevus which clinician understand easily.[4]

White adults have ten to forty cutaneous nevi on an average, but intraoral lesions are rare. Nevi are classified as acquired or congenital. Oral nevi follow the same classification as that of cutaneous nevi however; the term intradermal is replaced by intramucosal.

Pathophysiology

Although little doubt exist that nevus cells arise from the neural crest, whether the cells represent true melanocytes or are closely related. Distinct cell type is debatable. Melanocytes are located suprabasally in the epithelium, are dendritic cells and transfer melanin to the adjacent keratinocytes. On the contrary nevus cell has rounded cytoplasm and lack the dendritic processes, typical of melanocytes. Normally melanin is retained by nevus cells and not transferred to adjacent keratinocytes.

The intramucosal nevus is composed of a bulk of nevus cells in the mucosal epithelium. Approximately 15% of intramucosal nevi are non-pigmented. Melanotic nevi can be present at birth, or they may appear shortly after birth.

CASE REPORT

A 26-year-old male presented at the outpatient department with the chief complaint of irritation from lower anterior teeth and a mass present on upper front region of jaw [Figure 1]. Tumor was present since birth, was red in color initially and it gradually increased to its present size.

Figure 1

Preoperative view before extraction

Patient sustained an accident one year back, which caused loss of right, lateral incisor and following accident the color of the mass changed to black. Lesion was asymptomatic otherwise.

Clinical examination revealed an indurate, black nodular lesion of about 8-10 cm in diameter, firm in consistency and rough textured with irregular margins.

Periodontal probe was used to detect any false or true pocket but there was no evidence of periodontal disease. Radiographically, neither the bone loss nor any sign of radiolucency was present. Preoperative clinical diagnosis was fibrous enlargement vis-à-vis to melanoma. Patient was advised extraction of right central incisor [Figures 2 and 3] (In consultation with department of prosthodontic to rule out its interference with fixed prosthesis fabrication.)

Figure 2

Preoperative facial view after extraction

Figure 3

Preoperative palatal view

Treatment

Incision biopsy was performed. Following histological report of nevus, gingivectomy was undertaken with adequate alveoloplasty [Figures 4 and 5]. Healing was satisfactory after one month [Figure 6].

Figure 4

Intra operative view (after gingivectomy)

Figure 5

Excised tissue

Figure 6

Post operative view (after one month)

Histological findings

H and E section revealed parakeratinized stratified squamous epithelium. Pigmented nevus cells were seen in circumscribed groups (theques) in the connective tissue subjacent to the epithelium. Chronic inflammatory cells were also present around the theques. A diagnosis of Intramucosal Melanotic Nevi was offered [Figures 7 and 8].

Figure 7

Histopathologic view (H and E ×100)

Figure 8

Histopathologic view (H and E ×400)

The patient remained uneventful almost one year following operation till date and is advised follow up.

DISCUSSION

Nevi are benign lesion, present commonly on the skin but also occur in oral mucosa. They may present as round or oval well circumscribed; slightly raised in 65-80% cases. Oral nevi are usually smooth and rarely have a papillated or rough surface. In present case Nevi was neither well circumscribed nor round and smooth but had irregular margins and was multi polypoid in nature. The Intramucosal type of oral nevus is most common by far and represents 63[5] to 70%[6] of all oral nevi, most common on the hard palate (40%). Second most common location is the buccal mucosa (20%), 10% of all types of oral nevi are found on gingiva. Among all nevi approximately 17% of intramucosal nevi are on the gingiva.[7] The present case of intramucosal nevi was on gingival surface, a rare finding. About 75% of the nevi smaller than 0.6 cm. Nevi larger than 1.3 cm were present in only about 5% of the cases. The present case is unique with an exceptional large size of 8-10 cm. In general, the larger nevi are considered to be congenital akin to the present case.[8]

CONCLUSION

Although congenital nevi in the oral cavity have been reported, they are extremely rare, none underwent malignant transformation. Further gingival surface nevi, an exceptional giant size is unique to the present case.