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CASE REPORT
Year : 2017  |  Volume : 6  |  Issue : 3  |  Page : 181-184

Pigmented intramucosal nevus of gingiva with a special insight on its pathophysiology: Report of a rare entity


Department of Oral Pathology and Microbiology, Mamata Dental College, Khammam, Telangana, India

Date of Web Publication25-Sep-2017

Correspondence Address:
Rithika Bashamalla
Department of Oral Pathology and Microbiology, Mamata Dental College, Khammam - 507 002, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2277-8632.215529

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  Abstract 

Oral melanotic nevi can be characterized as developmental malformations or melanocytic tumors. Nevi are benign in nature originating from proliferating malfunctioning melanoblasts of the neural crest cells either in the epithelium or in connective tissue. It is an infrequent oral lesion triggering focal pigmentation. Considerable debate exists in the literature with respect to their origin, development, maturation, and their association to oral melanocytes. Nevi present in the mucous membrane have been documented to ensure the risk of malignant transformation. Hence, it is appropriate to cautiously diagnose all pigmented lesions of the oral cavity. Here, we report a case of intramucosal nevus with unusually large size in maxillary anterior gingival mucosa.

Keywords: Gingiva, intramucosal nevus, melanoblasts, melanocyte


How to cite this article:
Bashamalla R, Rao GV, Ramulu S, Sravya T. Pigmented intramucosal nevus of gingiva with a special insight on its pathophysiology: Report of a rare entity. J NTR Univ Health Sci 2017;6:181-4

How to cite this URL:
Bashamalla R, Rao GV, Ramulu S, Sravya T. Pigmented intramucosal nevus of gingiva with a special insight on its pathophysiology: Report of a rare entity. J NTR Univ Health Sci [serial online] 2017 [cited 2020 Apr 6];6:181-4. Available from: http://www.jdrntruhs.org/text.asp?2017/6/3/181/215529


  Introduction Top


The generic term nevus refers to malformations of the skin and mucosa that are congenital or developmental in nature. Pigmented nevus is a tissue malformation due to excessive proliferation of nevus cells. Nevus is a term that may be designated to any congenital lesion of various cells or tissue types.[1] In 1943, Ackermann and Field reported the first case of oral nevus. Comerford et al. was the first to propose the term intralamina propria nevus. King et al., in 1967, reported pigmented nevi as a rare entity in the oral cavity as they were found only in 0.1% of the patients in a large scale survey; they coined a specific term as intramucusal nevus.[2]

Nevi are benign tumors of the skin and mucosa characterized by the presence of melanin-producing, neuroectodermal derived cells.[2] Although nevi are common lesions that are seen on the skin, intraorally they are rare.[3] Nevi are distinctly uncommon, usually small in size (0.1–0.6 cm in diameter), and located anywhere in the oral cavity.[4] Nevi located in the mucous membrane have been identified as having the most potential for malignant transformation. Hence, it should be diagnosed appropriately.[5] This paper presents a case of unusually large intramucosal oral melanotic nevus presenting on gingiva with an unusual history of pain.


  Case Report Top


A 23-year-old female presented with a swelling in the upper front region of the jaw since 6 months. The swelling progressed slowly to the present size, which was asymptomatic initially but became associated with pain since 1 month. Intraorally, a solitary black nodular lesion on the maxillary anterior gingival mucosa, which was oval in shape and measuring 2 × 1 cm in diameter was noticed [Figure 1]. The lesion was firm in consistency and rough textured with irregular margins.
Figure 1: Patient presenting pigmented growth on anterior maxillary gingival mucosa

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Based on the clinical features, oral melanotic macule, pigmented nevus, melanoacanthoama, and melanoma were considered in the differential diagnosis. Excisional biopsy was performed and the sample was sent for histopathological examination [Figure 2].
Figure 2: Grossing specimen

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Histopathologyrevealed hyperplastic parakeratinized stratified squamous epithelium with the underlying cellular fibrous connective tissue [Figure 3] and [Figure 4]. The stroma revealed nests or theques of nevus cells in the form of islands and sheets. Nevus cells were large, round-to-oval in shape, and with melanin pigment. Nevus cells were not in interaction with the superficial epithelium. The rest of the stroma was fibrous with diffuse chronic inflammatory cell infiltrate. Histopathological features were suggestive of intramucosal nevus. The section was stained with Masson Fontana stain to support the diagnosis [Figure 5] and [Figure 6].
Figure 3: Photomicrograph showing islands and nests of nevus cells in the underlying connective tissue stroma [Hematoxylin and Eosin, ×100]

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Figure 4: Photomicrograph showing islands of nevus cells in the underlying connective tissue stroma [Hematoxylin and Eosin, ×400]

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Figure 5: Photomicrograph showing nests of nevus cells in connective tissue stroma [Masson Fontana stain, ×100]

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Figure 6: Photomicrograph showing round to ovoid nests of nevus within the connective tissue stroma [Fontana stain, ×400]

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  Discussion Top


Oral melanocytic nevi are benign tumors of melanocytes. Becker in 1927 first identified melanocytes in the oral epithelium. During early stages of intrauterine life, precursors of melanocytes, i.e. melanoblasts differentiate into the dendritic cells and migrate to the epidermis from the neural crest.[1] Nevus that are thought to originate from melanocytes have hydropic swollen nucleoli that occupy a large portion of nucleus.[2] Buchner and Hansen reviewed multiple cases of oral nevi and reported the clinical variants as 55% intramucosal type, followed by common blue nevus (32%), compound nevi (6%), junctional nevi (5%), and combined nevi (2%). They also reviewed the percentage of incidence of nevus at various sites of oral cavity [Table 1].[3] Various other studies have also been documented at various sites.[1],[2],[3],[5] Nevi are typically small in size measuring between 0.1 and 0.6 cm in diameter and are asymptomatic.[4] In the present case, the lesion was remarkably large with about 2 × 1 cm in diameter, which is relatively uncommon, and present on the maxillary anterior gingival mucosa. The present case was also associated with history of pain which is exceptional; only one case of nevi with pain has been reported.[3] Three theories exist for the development of tumor [Table 2].[1],[5]
Table 1: Distribution of Incidence Percentage of Oral Nevus

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Table 2: Theories of the Development of Oral Nevi

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Macroscopically, nevi may proliferate in two configurations, i.e. Unna's and Meischer's nevi. In Unna's nevi, nevus cells develop in a papillary or round pattern, giving an exophytic outlook, whereas in Meischer's nevi, there is diffuse insinuation of the cells into the subepithelial region giving an endophytic outlook.[5]

Histopathologically, melanocytic nevi are classified into three stages. (A) Junctional nevus: Lesional cells are found at the epithelial mesenchymal junction; (B) Compound nevus: Lesional cells exist in the junctional and underlying connective tissue area; and (C)Intramucosal nevus: Lesional cells are solely located within the connective tissue.[6]

Zones of different types of nevus cells are often appreciated during the development of the lesion. (I) Type A nevus cells (epithelioid): These are superficial cells which classically appear large epithelioid, with ample cytoplasm; (II) type B nevus cells (lymphocyte-like): These are round-to-polygonal cells, which ensure less cytoplasm and are present in intermediate portion of the lesion; (III) type C nevus cells (spindle-shaped): These cells appear small and round with spindle-shaped nuclei, considerably like Schwann cells or fibroblasts, and are present in deeper portion of lesion.[6]

Nevi in the mucous membrane have been recognized to ensure threat of malignant transformation into melanoma; nevertheless, some current studies contradict this assertion. However, due to the malignant potential of nevi and due to the presence of pigmented macules with preliminary oral melanoma, it is desirable to cautiously diagnose all pigmented lesions of oral cavity. The ideal treatment is the removal of lesion with a safety margin of 2 mm.[7]

To the best of our knowledge, our case of intramucosal nevus is the second to be reported with pain, which can be attributed to trauma or psychological factors.[3] The size of the lesion in the present case was remarkably large in contrast to the previously reported cases.[1],[2],[3],[4],[5],[6] In addition to the unusual size of the lesion, the present case was present in an, infrequent site i.e. anterior maxillary gingival mucosa.


  Conclusion Top


Various pigmented lesions have similar presentations posing a diagnostic dilemma for the dental surgeon. Hence, a careful diagnostic approach should be used when confronting pigmented lesions in the oral cavity.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Jain A, Shetty DC, Rathore AS, Kumar K, Juneja S. Non-pigmented intra mucosal nevi in a young female patient: A rare case report. J Med Radiol Pathol Surg 2015;1:18-21.  Back to cited text no. 1
    
2.
Kumar RV, Kranthi K, Seshan H. Pigmented intramucosal nevus of gingiva: A case report. Int J Contemp Dent 2010;1:14-9.  Back to cited text no. 2
    
3.
Beena VT, Chauhan I, Heera R, Rajeev R. Oral melanotic nevi: A case report and review of literature. Oral Maxillofac Pathol J 2010;1:976-1225.  Back to cited text no. 3
    
4.
Freitas DA, Bonan PR, Sousa AA, Pereira MM, Oliveira SM, Jones KM. Intramucosal Nevus in the Oral Cavity. J Contemp Dent Pract 2015;16:74-6.  Back to cited text no. 4
[PUBMED]    
5.
Dutta D, Kamath VV, Rajkumar K. Oral melanocytic nevi: Report of two cases with immunohistochemical elaboration of their probable origin and maturation. Indian J Dermatopathol Diagn Dermatol 2015;2:29-33.  Back to cited text no. 5
  [Full text]  
6.
Neville WB, Damm D, Allen CM, Bouquot JE. Oral and Maxillofacial pathology. 3rd ed. Saunders: Philadelphia; 2013-14. p. 382-5.  Back to cited text no. 6
    
7.
Tsao H, Bevona C, Goggins W, Quinn T. Transformation rate of moles (melanocytic nevi) into cutaneous melanoma. Arch Dermatol 2003;139:282-8.  Back to cited text no. 7
[PUBMED]    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
 
 
    Tables

  [Table 1], [Table 2]



 

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