Head and Neck Pathol (2015) 9:481–487

DOI 10.1007/s12105-015-0639-8

ORIGINAL PAPER

Oral Congenital Melanocytic Nevus: A Rare Case Report

and Review of the Literature
Helvécio Marangon Júnior1 • Paulo Eduardo Alencar Souza1 •
Rodrigo Villamarim Soares2 • Bruno Augusto Benevenuto de Andrade3 •

Oslei Paes de Almeida4 • Martinho Campolina Rebello Horta1

Received: 25 March 2015 / Accepted: 29 June 2015 / Published online: 5 July 2015
Ó Springer Science+Business Media New York 2015

Abstract Melanocytic nevi are congenital or acquired Introduction

benign proliferations of cells of melanocytic origin. Oral
congenital melanocytic nevi are rare, and only a few cases Melanocytic nevi are congenital or acquired benign pro-
have been reported in the literature. The purpose of this liferations of cells of melanocytic origin derived from
study is to present the clinical, histological and immuno- neural crest [1]. These lesions are typically found on the
histochemical features of an oral congenital melanocytic skin, and they are uncommon in the oral mucosa [2–4]. An
nevus in a 16-year-old female with an 11-year follow-up estimated annual incidence of 4.35 cases per 10 million
and to review the pertinent literature. The reported case is individuals has been previously described for excised oral
the fifth well-documented case report of oral congenital melanocytic nevi (OMN) [4]. OMN are observed mainly in
melanocytic nevus in the English literature and the first the hard palate and buccal mucosa, affecting women more
with a long period of follow-up, thereby making it an frequently with an average age of 35 years [3].
important contribution to the knowledge regarding this The term congenital melanocytic nevus (CMN) should
uncommon oral mucosa lesion. be applied to benign melanocytic proliferations present at
birth as well as to lesions that, although not apparent at
birth, show typical clinical and histological features of
Keywords Oral mucosa
Congenital melanocytic nevus

CMN [5]. Oral CMN is rare, and to date, only four well-
Histopathology
Immunohistochemistry
documented cases have been reported in the English liter-
ature [6–9].
Here, we report a case of an oral CMN in a 16-year-old
female patient; we discuss its clinical, histopathological,
and immunohistochemical features and we review the
pertinent literature.
& Martinho Campolina Rebello Horta
martinhohorta@pucminas.br
1
Oral Pathology Division, School of Dentistry, Pontifical Case Report
Catholic University of Minas Gerais (PUC Minas), Av. Dom
José Gaspar 500, Prédio 46, Sala 110, Belo Horizonte,
MG CEP: 30535-901, Brazil
A 16-year-old female white patient complaining of ‘‘a
2
growth in the cheek’’ was referred to the Oral Pathology
Periodontology Division, School of Dentistry, Pontifical
Catholic University of Minas Gerais (PUC Minas),
Clinic at Pontifical Catholic University of Minas Gerais
Belo Horizonte, MG, Brazil (PUC Minas). She reported that she had the lesion since
3 childhood and that a slow and continuous growth occurred.
Oral Pathology Division, Department of Oral Diagnosis and
Pathology, School of Dentistry, Federal University of Rio de The medical history of the patient was not contributory.
Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil An extra-oral clinical examination showed no alter-
4
Oral Diagnosis Department, Piracicaba Dental School, ations. An intra-oral clinical examination showed a large
University of Campinas (UNICAMP), Piracicaba, SP, Brazil diffuse swelling on the left buccal mucosa, extending to the

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retromolar triangle and lower posterior alveolar mucosa. epithelium showed no melanin in basal cells or melano-
The lesion showed ill-defined borders, was approximately cytic hyperplasia (Fig. 2c, d). Based on the clinical and
5 9 4 cm in size, and was formed by numerous diffuse histopathological features, the diagnosis of oral CMN was
papules (each measuring 1–4 mm in diameter). Some established.
papules were similar in color to the normal mucosa, and To better characterize the case, immunohistochemistry
others displayed various scattered pigmented areas, ranging for HMB-45, fatty acid synthase (FASN), S-100, bcl-2, and
from brown to black (Fig. 1a). No involvement of the Ki-67 was performed. The melanocytic cells were negative
ipsilateral mucosa of the floor of the mouth or tongue was for HMB-45 (Fig. 3a) and positive for FASN, S-100 and
observed. There is also no change in color of the overlying bcl-2 (Fig. 3c–e). Finally, the positivity of the melanocytic
skin. Moreover, mandibular bone alterations in the area of cells for Ki-67 was \1 % (Fig. 3f).
the lesion were not identified in periapical radiographs. The patient has been under close follow-up for the last
A clinical diagnosis of melanocytic nevus or malignant 11 years. Despite a slight increase in the number of pig-
melanoma was proposed. An incisional biopsy was per- mented areas in the lesion during these years, there were no
formed, and H&E-stained histological sections showed an significant changes in its clinical features (Fig. 1b).
oral mucosa lined by parakeratinized squamous epithelium
with hyperplasia and a dense diffuse infiltrate of small
monomorphous melanocytes (nevus cells) in the lamina Discussion
propria (Fig. 2a, b). The nevus cells were arranged in a
band-like pattern (Fig. 2a, b), streaming through collagen The oral mucosa is an uncommon site for the presentation
bundles and occasionally presenting melanin, but without of a melanocytic nevus [2–4]. As its cutaneous counterpart,
cellular atypia or mitosis (Fig. 2c–f). The mucosa OMN can be congenital or acquired. Nevertheless, con-
genital OMN is a very rare lesion [9]. To the best of our
knowledge, this is the fifth well-documented case report of
oral CMN in the English literature (Table 1). Similar to the
present case, all previously reported cases occurred in
young female patients, and they were located on the gin-
giva of a 3-year-old [6], labial mucosa of a 7-year-old [7],
buccal mucosa of a 19-year-old [8], and palatal mucosa of
a 19-year-old patient [9].
Cutaneous CMN appears as a flat café au lait spot at
birth, and during the first years of life, it can appear as dark
brown macules, papules or plaques, which can display a
heterogeneous pattern. Some degree of hypo pigmentation
within the lesion, the occurrence of verrucous changes and
hypertrichosis, as well as satellite lesions, have also been
described [1, 10]. CMN is traditionally divided according
to size into small (up to 1.5 cm), medium (1.5–19.9 cm),
and large or giant (20 cm or more) [10]. Although the
incidence of CMN in the general population is elevated at
1:100 live births, when only giant nevi are considered, this
number is drastically reduced to 1:20,000 [11].
In the four cases of oral CMN previously reported
(Table 1), the main clinical characteristics were well-de-
marcated plaques or papules showing homogenous or
scattered pigmentation and small size, with all lesions
displaying a diameter of no more than 1.5 cm. Although
the present case also displayed a papular surface and dis-
persed pigmented area, its ill-defined borders and larger
Fig. 1 Intra-oral view of the lesion. a Located on the left buccal size differs from the previous cases.
mucosa, retromolar triangle and lower posterior alveolar mucosa, the The differential diagnosis of OMN generally includes
lesion was formed by numerous diffuse papules displaying various
pigmented lesions of the mouth, such as melanotic macule,
scattered pigmented areas. b After an 11-year follow-up, regardless of
a slight increase in the number of pigmented areas, no significant physiological pigmentation, smoker’s melanosis, amalgam
clinical changes were observed tattoo, and malignant melanoma [12]. In the present case,

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Fig. 2 Histopathological features of the lesion. Oral mucosa pre- melanin in basal cells or melanocytic hyperplasia was observed in the
senting a diffuse infiltrate of small monomorphous melanocytes mucosa epithelium, a HE 940; b HE 9100; c HE 9400; d HE
arranged in a band-like pattern in the lamina propria, streaming 91000; e HE 9400; f HE 91000
through collagen bundles and showing melanin production. No

due to its size and heterogeneous pigmented surface, the CMN differs from acquired nevus because of its pres-
differential diagnosis was restricted to melanocytic nevus ence at birth, larger size, and histopathological features.
and malignant melanoma. Histopathologically, both types may be junctional,

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Fig. 3 Immunohistochemical features of the lesion. a Cells were positive for bcl-2 (streptavidin-biotin-peroxidase 9400). f The pos-
negative for HMB-45 (Permanent Red 9400). b Malignant melanoma itivity of the melanocytic cells for Ki-67 was \1 % (streptavidin-
samples employed as a positive control for HMB-45 (Permanent Red biotin-peroxidase 9400). Keratinocytes of the oral mucosa epithelium
9400). c Cells were positive for FASN (Permanent Red 9400). were used as an internal positive control
d Cells were positive for S-100 (Permanent Red 9400). e Cells were

compound or intradermal (intra mucosal), but CMN gen- cell nest formation of acquired nevus [1, 5]. Although this
erally shows a diffuse band-like infiltrate of melanocytes suggestive histological feature was observed in the present
streaming through collagen bundles rather than the classic case, the oral CMN reported by Takeda [7] showed the

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Table 1 Features the oral CMN previously reported in the English literature
Authors Age Gender Clinical features Histopathology Immunohistochemistry Management/outcome

Allen and 3- Female Dark brown plaque with Intramucosal sheets of Not performed Excisional biopsy with no
Pellegrini year- uniform margins; located melanocytes just beneath recurrence after
[6] old at the right posterior the oral mucosa 6 months follow-up
mandibular lingual epithelium, extending to
gingiva; not noticed the deep margin of the
previously; dimensions: sample; melanin
0.8 9 1.5 cm deposits; no cellular
atypia or mitosis
Takeda [7] 7- Female Brownish-black, well- Intramucosal nests of Not performed Excisional biopsy with no
year- circumscribed tumor; ovoid-shaped nevus recurrence after 3 years
old located at upper labial cells, extending from follow-up
mucosa; noticed since lamina propria to deep
birth; dimensions: submucosal connective
0.65 9 0.7 cm tissue; scattered
multinucleated giant
cells; no cellular atypia
or mitosis; hyperplasia
of the oral mucosa
epithelium
Rose et al. 19- Female Multiple and widespread Performed only in skin Performed only in skin Excision of 3
[8] year- pigmented papules, lesion samples; lesion samples: representative skin
old nodules and tumors; intradermal, round to S-100 (positive) nodules for
located at lower back, oval, monomorphous histopathology and
HMB-45 (negative)
trunk, palms, soles, face melanocytes arranged in immunohistochemistry;
and buccal mucosa; nodular and plexiform no follow-up
noticed since birth; patterns; few scattered
dimensions: 20 cm spindle-shaped
(lower back) and melanocytes; melanin
0.5–5 cm (other sites); deposits; splaying of
the specific features of melanocytes between
the oral mucosa lesion collagen fibers
were not specified
Gilbert 19- Female Well-demarcated circular Intramucosal sheets of melan A (positive) Incisional biopsy
et al. [9] year- plaque, predominantly mature nevus cells HMB-45 (scanty- followed by excisional
old erythematous with extending deep in the positive) biopsy; no follow-up
scattered brown lamina propria and
Ki-67 (scanty-
pigmentation; located at around salivary gland
positive)
palatal mucosa; noticed ducts and nerves;
since 3 months of age; melanin deposits;
dimensions: scattered multinucleated
1.2 9 1.1 9 0.3 cm giant cells; no cellular
atypia or mitosis;
papillomatous oral
mucosa epithelium
Marangon 16- Female Diffuse swelling showing Dense diffuse HMB-45 (negative) Incisional biopsy; no
Junior year- papular surface, intramucosal infiltrate of FASN (positive) surgical excision; no
et al. old scattered pigmented small monomorphous significant changes after
S-100 (positive)
(current areas and ill-defined melanocytes, arranged in 11 years follow-up
case) borders; located at the a band-like pattern; bcl-2 (positive)
left buccal mucosa splaying of melanocytes Ki-67 (\1 %)
extending to alveolar between collagen fibers;
mucosa and retromolar no cellular atypia or
triangle; noticed since mitosis; no melanin in
childhood; dimensions: basal cells or
5 9 4 cm melanocytic hyperplasia;
hyperplasia of the oral
mucosa epithelium
The current case was also included

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classic nests of nevus cells (Table 1). Therefore, the his- marker in oral melanomas and its very low expression in
tological aspects of CMN are variable, and pathognomonic oral intramucosal nevi were recently reported, confirming
characteristics do not occur in most of the cases [1, 10]. that Ki-67 can be useful in the differential diagnosis of
Small CMN is not easily diagnosed if not identified at birth benign and malignant melanocytic lesions of the oral cavity
because its clinical features can be similar to acquired [20].
nevus [1, 9]. The present case was diagnosed as congenital The major reasons for treating CMN are the risk of
due to its clinical and histological characteristics. The malignant transformation and aesthetic motives. Surgical
patient reported the presence of the lesion since childhood, excision has been recommended as the first treatment
although no information was provided about the lesion at choice. Although total excision of cutaneous lesions may
birth. This does not eliminate the possibility that the lesion result in high aesthetic satisfaction, its efficacy in reducing
was apparent at birth because the identification of intraoral the incidence of malignant melanoma remains unproven
lesions is more difficult than cutaneous lesions in new- [21]. Transformation of cutaneous CMN to melanoma
borns. Furthermore, as mentioned above, it is important to appears to be related to its size, and the reported risk ranges
emphasize that the diagnosis of CMN does not depend on from 1.1 to 45 % [10].
its presence at birth but mainly on the presence of sug- There is no evidence of malignant transformation of
gestive clinical and histological features [5]. In fact, of the OMN to melanoma, even in patients with multiple or
four previously reported cases of oral CMN, two had been congenital nevi [4]. In the present case the patient did not
noticed since birth [7, 8], one at 3 months of age [9] and receive any treatment, the lesion was not surgically
one at 3 years [6] (Table 1). removed due its large size, and during the 11-year follow-
The immunohistochemistry assays conducted in this up, no significant clinical changes were observed.
study revealed that the lesion was negative for HMB-45, In summary, oral CMN is a rare lesion, and knowledge
whereas a malignant melanoma sample used as a positive regarding its features is essential for its appropriate diag-
control showed positivity for this marker (Fig. 3b). HMB- nosis and management by clinicians. The reported case
45, although very useful for the diagnosis of melanoma, contributes to the knowledge regarding oral CMN’s clini-
can also be positive in benign melanocytic lesions [13, 14]. cal, histopathological, and immunohistochemical features,
In fact, the oral CMN reported by Gilbert et al. [9] showed and it is the first with a long period of follow-up.
scanty-positivity for HMB-45. It is interesting that the
present case was positive for FASN, a key enzyme in fatty Acknowledgments Coordenação de Aperfeiçoamento de Pessoal de
Nı́vel Superior (Capes), Brazil; Conselho Nacional de Desenvolvi-
acid synthesis responsible for converting acetyl-CoA to mento Cientı́fico e Tecnológico (CNPq), Brazil; Fundação de Amparo
malonyl-CoA and long-chain fatty acids. Increased à Pesquisa do Estado de Minas Gerais (FAPEMIG), Brazil.
expression of this protein has been found in different
malignancies, including malignant melanoma, due to the Conflict of interest The authors declare that they have no conflict
of interest.
increased cellular energy demand of neoplastic cells [15].
Additionally, it was suggested that it can be useful for
distinguishing between melanoma and nevus, as the latter
is negative for FASN or expresses it weakly [16, 17]. References
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