Case Report
Blue Nevus of the Hard Palate in a 12-Year Old Male Patient: A Case Report with Review of the Literature
Cameron Y S Lee1*, Kristin L Lee2, Kirk Y Hirata3 and David C Ching4
1Oral Maxillofacial and Reconstructive Surgery, Aiea, Temple University School of Dentistry, Philadelphia, USA
2Third Year Dental Student, Creighton University School of Dentistry, Omaha, USA
3Department of Pathology, The Queen's Medical Center. Honolulu, HI, University of Hawaii, John A. Burns School of Medicine, USA
4Private Practice in Pediatric Dentistry, Pearl City, USA
*Corresponding author: Cameron Y. S. Lee, Oral Maxillofacial and Reconstructive Surgery, Aiea, HI Professor of Surgery, Temple University School of Dentistry, Philadelphia, PA 19140 USA
Published: 31 Mar, 2017
Cite this article as: Lee CYS, Lee KL, Hirata KY, Ching DC.
Blue Nevus of the Hard Palate in a 12-
Year Old Male Patient: A Case Report
with Review of the Literature. Clin Surg.
2017; 2: 1399.
Abstract
Background and Overview: Nevi are either congenital or developmental pigmented malformations
rarely found in the oral cavity. Approximately 30% of reported cases in this anatomical region are
of the blue type, a histological variant with the potential for malignant transformation. There is
no consensus in the literature regarding biopsy of pigmented lesions with malignant potential. In
children, the intraoral blue nevus is rare. This case report describes the clinical features of a blue
nevus in a 12- year old Asian male on the right hard palate of the maxilla. A differential diagnosis,
rationale for excisional biopsy of this oral lesion and review of the literature are presented. The goal
of this case report is to create awareness that such a rare pigmented lesion in the oral cavity can also
occur in children.
Case Description: This case report describes the clinical presentation of a 12-year old Asian male
who presented with a dark blue-black pigmented lesion on the right hard palate of the maxilla.
Because of the fear that the pigmented lesion could represent a malignancy, excisional biopsy for
histopathologic diagnosis was performed.
Practical Implications: Although blue nevi are considered rare in the oral cavity, especially in
children it is important to differentiate these lesions from the malignant blue nevus or melanoma. To
obtain a definitive diagnosis of any suspicious pigmented lesion, excisional biopsy is recommended
due to the potential for malignant transformation.
Keywords: Blue nevus; Rare; Child; Differential diagnosis; Biopsy
Introduction
Nevi are congenital or developmental pigmented malformations commonly located on the
skin. Depending on the location of the nevus cells, the malformation is classified histologically
as intradermal, junctional, compound and blue nevi [1]. The blue nevus is a neoplasm that is
composed of pigmented dendritic dermal melanocytic cells in the reticular dermis with the potential
for malignant transformation [2]. A blue nevus can develop anywhere on the body, however,
approximately 50% of the common blue nevi are usually located on the dorsal surface of the hands
and feet, scalp, and buttocks [1,2]. A blue nevus in the oral cavity is considered a rare lesion with
important differential diagnoses [3]. Although considered a benign lesion, it may have the potential
for malignant transformation in rare cases [4].
In 1959 Scofield described the first two cases of blue nevi which were both located on the hard
palate [5]. Since the first two reports, approximately 70 additional cases have been reported [5,6].
Two histological variants were described in these reports: a common blue nevus and a cellular blue
nevus [7]. Intraoral blue nevi present as asymptomatic, slightly raised well-circumscribed lesions of
variable color, such as gray, blue-black and brown [7-9]. The most common location of the intraoral
blue nevus is the hard palate and is just over 5.0 mm in diameter [10]. The present case report
describes a blue nevus on the hard palate of a 12-year old Asian male and discusses the differential
diagnosis, rationale for excisional biopsy of this pigmented lesion and a review of the literature.
Case Presentation
A healthy 12-year old Asian male was referred to the office of one of
the authors (CYSL) for evaluation of a blue-black colored pigmented
lesion on the right hard palate of the maxilla. The parents stated that
the lesion was noticed about two years ago and may be increasing in
size. The family was concerned that the pigmented lesion could be a
malignant growth. Dental history revealed teeth letters B, I, J, K, L
restored with amalgam from 2010 to 2014. Oral examination revealed
a complete adult restoration-free dentition, except the third molars
that were not present. Examination of the right hard palate of the
maxilla revealed a blue-black elliptical shaped macule with distinct
margins (Figure 1). With digital pressure, blanching of the lesion was
not observed. In addition, no vascular bruit or thrill was appreciated.
To obtain a definitive diagnosis, excisional biopsy was completed.
Differential diagnosis
The differential diagnosis of intraoral nevi includes amalgam
tattoo, melanotic macule, melanocytic nevi, vascular anomaly and
melanoma [11]. Of the five possibilities, the amalgam tattoo is the
most difficult to differentiate from a blue nevus and is one of the most
common causes of intraoral pigmentation [12]. It presents clinically
as a localized flat, blue-gray lesion of variable size and is the result
of localized implantation of dental amalgam that appears as a blue,
gray or black macule. Blue nevi were most commonly clinically
diagnosed as amalgam tattoos. These findings are in agreement with
previous studies [8]. No treatment is indicated for removal of the
amalgam tattoo, unless a melanocytic neoplasm cannot be excluded.
In our patient, the entire dentition was without any restorations, but
amalgam tattoo could not be excluded from the differential diagnosis
because of the past dental history of primary teeth restored with
amalgam.
The melanotic macule is a pigmented oral lesion of unknown
etiology that is more commonly observed than the blue nevus [6].
It occurs at any age, but is seen normally in adults with a female
predilection. Although these are innocuous lesions, a biopsy is usually
warranted for diagnosis because mucosal melanoma can mimic the
appearance of a melanotic macule [12]. The classic features include
a round, well demarcated, smooth macule that is usually brown in
color but may appear blue or black. The vermilion border of the lower
lip is the favored site of occurrence, followed by the buccal mucosa,
gingiva and palate. Like the amalgam tattoo, no treatment is indicated
unless the melanotic macule becomes an aesthetic or malignancy is a
concern.
Small vascular anomalies of the oral cavity, such as the
hemangioma or varices may look similar to the blue nevus. A
hemangioma is a common congenital vascular lesion that presents as a blue-purple colored fluctuant nodule [13]. Blanching with digital
pressure is a characteristic feature and can be consistently used to
rule-out a vascular lesion. Another vascular anomaly to rule-out is
the varix that has a nodular appearance that is blue-purple in color
[14]. With digital pressure, like the hemangioma, it will blanch with
digital pressure. The lip, tongue and floor of the mouth are common
sites for this vascular anomaly. Varices are not commonly observed
in children.
Pigmented nevi are rarely the etiology for focal oral pigmentation
[8]. They often present as either brown or blue lesions. Histologically,
nevus cells are observed in the basal epithelial layers, the connective
tissue or both. Therefore, they are classified as junctional, intradermal,
intramucosal and compound nevi [1,2]. Of the different types of
pigmented nevi, blue nevi are characterized by a proliferation of
dermal melanocytes deep within the lamina propria, which accounts
for the surface blue color [2,3,7-14]. It may be difficult to clinically
diagnose a nevus from a mucosal melanoma. This is especially if the
lesion is on the palate, as this is the most common site for both lesions
[15]. Although transformation of oral pigmented nevi to melanoma
is questionable, nevi may represent a precursor to oral mucosal
melanoma [15]. Excisional biopsy is therefore recommended for
histopathologic examination.
The anatomic location of oral melanoma is most frequently
observed on the hard palate and maxillary gingiva. Malignant
melanoma develops from malignant melanocytes [16]. They exhibit
a very poor prognosis when discovered within the oral cavity [17].
Melanoma usually occurs over the age of 50 years and the incidence
is greater in males. Oral melanoma can occur in any racial and ethnic
group, but the highest incidence is observed in Japanese patients [18].
Therefore, melanoma should always be considered in the differential
diagnosis as it cannot be clinically distinguished from a melanotic
nevus [19].
In our patient, histopathology revealed pigmented spindleshaped
cells with branching dendritic extensions deep in the lamina
propria (Figure 2). High power view revealed slender and elongated
melanocytes aligned parallel to the surface epithelium (Figure 3).
Based on the histopathologic findings, the diagnosis was negative for
a malignancy and consistent with a common blue nevus of the hard
palate.
Figure 1
Figure 2
Figure 3
Discussion
The blue nevus is an asymptomatic, benign melanocytic lesion
first described by Tièche in 1906 as small sharply defined blue to blueblack
spots commonly observed on the face and extremities [1,2]. It is
the second most common type of nevus of the oral cavity, accounting
for 19-36% of all cases [10,20]. The blue color of the nevus is due to the presence of melanin deep within the dermal melanocytes and the
Tyndall effect [1,2]. The variation in color is related to the depth of
the melanocytic cells in the dermis, the amount of melanin present,
and the presence or absence of melanin in the cells of the overlying
epidermis.
In the oral cavity, blue nevi are rare lesions with a prevalence
of 0.1% in the general population [1,7,8,16]. The predominant
intraoral site is the hard palate of the maxilla. Intraoral lesions have
a predilection for females in the third to fourth decades of life. In a
literature review by Fistarol et al. [21] from 1959 to 2005, 64 reports
of blue nevus were identified in the oral cavity. Six patients under the
age of 18 had biopsy proven blue nevi located on the hard palate.
Although blue nevi are considered rare in the oral cavity it is
important to differentiate these lesions from the malignant blue
nevus or melanoma [3,4,22-29]. Malignant transformation of blue
nevi has been reported in children in the head and neck region,
but no intraoral case reports have been reported [28,29]. To
obtain a definitive diagnosis of any suspicious pigmented lesion,
excisional biopsy is recommended due to the potential for malignant
transformation [19,24-29].
Conclusion
Accurate diagnosis of all pigmented lesions of the oral cavity is challenging and the decision to biopsy the lesion is not without controversy. Histopathological evaluation of oral pigmented lesions is required for a definitive diagnosis. We are of the opinion that biopsy of any pigmented lesion will allow the clinician to obtain a definitive diagnosis that will allow timely surgical management, if indicated.
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