|Year : 2014 | Volume
| Issue : 2 | Page : 49-52
Deadliest tumor of oral cavity: A rare case of intra oral malignant melanoma
Nunsavathu Purnachandrarao Naik1, Alaparthi Ravi Kiran1, Yalamanchili Samata1, Ambaldhage Vijay Kumar2
1 Department of Oral Medicine and Radiology, Sibar Institute of Dental Sciences, Takkellapadu, Guntur, India
2 Department of Oral Medicine and Radiology, PMNM Dental College and Hospital, Bagalkot, Andhra Pradesh, India
|Date of Web Publication||10-Mar-2015|
Nunsavathu Purnachandrarao Naik
Department of Oral Medicine and Radiology, Sibar Institute of Dental Sciences, Takkellapadu, Guntur, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Malignant melanoma is a rare tumor arising from the uncontrolled growth of melanocytes found in the basal layer of the epithelium. Although cutaneous malignant melanoma is the third most common malignancy of the skin, it accounts only for 3-5% of all dermal malignancies. Primary malignant melanoma of the oral mucosa is extremely rare, accounting for only 0.2-8% of all malignant melanomas. The incidence is slightly higher in males while others report a higher incidence in females. In the oral cavity, 80% of the cases occur in the maxilla with the prevalence of the hard palate or combined with the gingival or alveolar ridge. In this paper, we present a rare case of a 47-year-old female patient who reported with completely asymptomatic, pigmented growth in the maxillary anterior region.
Keywords: Magnetic resonance imaging, malignant melanoma, pigmented lesions
|How to cite this article:|
Naik NP, Kiran AR, Samata Y, Kumar AV. Deadliest tumor of oral cavity: A rare case of intra oral malignant melanoma. J Oral Res Rev 2014;6:49-52
|How to cite this URL:|
Naik NP, Kiran AR, Samata Y, Kumar AV. Deadliest tumor of oral cavity: A rare case of intra oral malignant melanoma. J Oral Res Rev [serial online] 2014 [cited 2020 May 27];6:49-52. Available from: http://www.jorr.org/text.asp?2014/6/2/49/152908
| Introduction|| |
Primary oral malignant melanoma is an extremely rare tumor arising from the uncontrolled growth of melanocytes. Melanocytes are the nonkeratinocytes, present in the basal and suprabasal layers of the oral mucosa. They are derived from neural crest cells and thus primary malignant melanoma has been described in almost all sites and organ systems to where neural crest cells migrate. It accounts for 0.2-8% of all malignant melanomas.  It occurs between the age of 30 and 90 years, with a higher incidence in the sixth decade.  In the oral cavity, 80% of the cases are localized in the maxilla with the prevalence of the hard palate or combined with the gingiva or alveolar ridge.  The clinical presentation of oral melanoma can vary widely from a typically pigmented macular or proliferative lesion to a nonpigmented, soft, vascular form. It may be single or multiple, primary or metastatic from other cutaneous melanomas.
| Case Report|| |
A 47-year-old female presented with a painless, pigmented, exophytic growth in the maxillary anterior region from past 6 months. The patient had noticed the growth around 6 months ago; initially it was small pigmented patch of size 1 cm, which gradually increased to attain the present size. The lesion was completely asymptomatic, and there was no history of secondary changes such as ulceration, discharge or mobility of teeth. There was no history of similar pigmented patch or growth elsewhere in the body. The medical, dental and family history was not significant.
On clinical examination, bilateral sub-mandibular lymph nodes were palpable. The nodes were solitary, oval in shape, around 1 cm × 1 cm in diameter, freely mobile, firm in consistency and nontender on palpation. Intra oral examination of the patient revealed an exophytic, pigmented growth on the maxillary anterior gingiva. The lesion was irregular in shape, dark brown to bluish-black in color, involving both marginal, attached and papillary gingiva of maxillary anterior region, extending medio-laterally from distal aspect of right first premolar to distal aspect of left lateral incisor, superio-inferiorly from the muco-buccal fold to marginal gingiva and palatal side extending around 2 cm from the marginal gingiva toward the hard palate, measuring around 4 cm × 1.5 cm in size. The lesion showed well defined, ragged borders and followed the contours of the interdental papilla. The surface of the lesion was slightly raised from the surrounding gingiva and was rough or papillary [Figure 1] and [Figure 2].
|Figure 1: A pigmented exophytic growth over the maxillary anterior gingiva|
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On palpation the lesion was soft to firm in consistency, nontender, the borders were slightly raised and the surface was papillary. There was no mobility of teeth in proximity of the lesion.
Based on the clinical features, provisional diagnosis of oral malignant melanoma was considered, and the differential diagnosis included, intraoral nevus, hemangioma, vascular malformations. Intra-oral periapical and occlusal radiographs of the area revealed no significant changes. As the lesion was arising from soft tissue, patient was advised for magnetic resonance imaging (MRI) scan of head and neck region. The MRI scan revealed a small soft tissue growth in the premaxillary area of upper alveolar gingival region with mild deviation of the nasal septum to the left side due to hypertrophy of right nasal turbinate [Figure 3]. An incisional biopsy was performed under local anesthesia that confirmed the diagnosis of malignant melanoma [Figure 4]. The patient was referred to a higher center for the treatment.
|Figure 3: Magnetic resonance imaging scan with small soft tissue swelling in the premaxillary area of upper alveolar gingival region with mild deviated nasal septum to the left side with hypertrophy of right turbinate|
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|Figure 4: Photomicrograph of lesion showing infiltration of numerous atypical pleomorphic melanocytes containing brownish-black granular pigment in the cytoplasm|
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| Discussion|| |
Melanoma is a malignant neoplasm arising from neural crest cells. Malignant melanoma in the oral cavity accounts only for 0.2-8% of all malignant melanoma. Despite the rarity of the disease, melanoma is the most important pigmented lesion in the oral cavity due to its deadly nature. Due to its variable clinical presentation and high mortality rate, oral biopsies of any pigmented lesions are aimed at excluding malignant melanoma. 
Although oral melanoma was first described by Weber in 1895, the etiology is still obscure. Cigarette smoking, denture irritation, tobacco and formaldehyde exposures, alcohol consumption are some of the suggested risk factors, but their correlation is still unclear. In the present case, the patient was not exposed to any of these factors and hence the possible etiological factor for this patient is still unclear.
Oral malignant melanoma may present clinically in a wide variety of forms. It appears most commonly as a pigmented lesion varying from dark brown to blue-black, some melanomas can be amelanotic.  A melanoma can be flat (macule) or elevated (nodule or tumor) with or without ulceration or an erythematous border, and reported cases vary in size from few millimeters to centimeters.
Lopez et al. identified five types of oral malignant melanoma on the basis of clinical appearance:
This case could be classified as the pigmented nodular type of oral malignant melanoma.
- Pigmented nodular type.
- Nonpigmented nodular type.
- Pigmented macular type.
- Pigmented mixed-type.
- Nonpigmented mixed type.
Dentists' should be highly suspicious of any pigmented lesion of the oral mucosa in the following situations. These are also called as ABCDE criteria to distinguish malignant melanoma from any other benign pigmented lesion. 
In the present case, all the above-mentioned criteria were fulfilled. The lesion was asymmetrical, irregular in shape, the edges were ragged, color varied from brownish-black to bluish-black, the size of lesion was more than 6 mm and the lesion was raised above the surface of surrounding gingiva.
- Asymmetry: The shape of the lesion is not same on the both sides.
- Border irregularity: The edges are ragged, notched or blurred.
- Color variegation: Pigmentation is not uniform, and many display shade of tan, brown or black. White, reddish or blue discoloration is of particular concern.
- Diameter: A diameter >6 mm is characteristic of melanoma, although some may have smaller diameters. Any growth in a simple nevus warrants evaluation.
- Evolving: Changes in the lesion over time are characteristic. This factor is critical for nodular or melanotic melanoma, which may not exhibit the classic criteria listed above.
Oral melanoma can present as a flat macule or an exophytic growth. Melanomas tend to exhibit two directional patterns of growth: Radial growth phase and vertical growth phase. It should be noted that even when melanoma becomes exophytic or ulcerated, it generally lacks the induration and rolled ulcerated border frequently seen in the oral squamous cell carcinoma. These features should not be used to judge whether a pigmented lesion is malignant as radial growth phage of melanoma could be prolonged with minimal or no invasion. During this phase the atypical melanocytes exhibit a pagetoid (upward migration) spread, resulting in uniform epithelial thickening and a lack of focal induration. 
Primary oral melanoma (POM) of the oral cavity is rare, even more exceptitional is the secondary form which metastasis in the oral cavity of primitive distant melanomas. When it is secondary or metastatic, the localization is more frequent in tongue, parotid, and tonsils. It is considered POM when the following criteria as described by Greene (1953) are fulfilled:
Delgado Azaρero and Mosqueda Taylor presented a practical and technically simple method for clinical diagnosis of POM, which allows differentiating its neoplasia from other pigmented lesions. The clinical test consists of rubbing the surface of the lesion with a gauze with the objective of verifying if it stains black due to the presence of melanin pigment on its surface. The authors refer that a positive result was obtained in 84.6% of the cases, that the method possesses an elevated sensibility to anticipate diagnosis, and that a negative results does not exclude the possibility of this neoplasia. Since there are cases in which the malignant cells have not involved the superficial layer of the epithelium. Melanoma that involves the mucosa of the region of the head and neck is more aggressive when it is present clinically as nodular lesion with a vertical growth that invades the sub mucosa.
- Demonstration of melanoma in the oral mucosa.
- Presence of functional activity.
- Inability to demonstrate extra oral primary melanoma.
Regarding the classification and prognosis, the criteria developed by Clark and Bresslow are not useful in the oral cavity because of the histological peculiarity it presents. Cebriαn Carretero et al. suggest a classification to establish prognosis based on three stages:
The American Joint Committee on Cancer has proposed criteria for staging of oral cancers, but not for the staging of oral malignant melanomas. Most practitioners use general clinical stages in the assessment of oral mucosal melanoma as follows:
- Tumor limited to the oral cavity.
- Tumor with lymphatic dissemination.
- Tumor with distant metastasis. 
The only study effective in diagnosing oral malignant melanoma is a tissue biopsy. Imaging studies such as contrast-enhanced computed tomography may be of benefit in determining the extent of the tumor and weather local, regional, or lymph node metastasis is present. Studies such as bone scanning with a gadolinium-based agent and chest radiography can be beneficial in assessing metastasis. 
- Stage I - Localized disease.
- Stage II - Regional lymph node metastasis.
- Stage III - Distant metastasis.
Medical therapy is not often beneficial for treating oral melanoma. Drug therapy, therapeutic radiation, and immunotherapy are used in the treatment of cutaneous melanoma. Ablative surgery with tumor free margins remains the treatment of choice. Early surgical intervention when local recurrence is detected enhances survival although radiation alone is reported to have questionable benefit (particularly in small fractionated doses), it is a valuable adjuvant in achieving relapse free survival when high fractionated doses are used. Multi-model therapy offers the best like hood of relapse free survival compared with any single therapy.  Kirkwood et al. showed that surgery followed by high dose interferon alfa-2 in high risk, cutaneous melanoma appears to be more beneficial than surgery followed by melanoma antigen vaccination. Although not evaluated in mucosal sites, these approaches may provide a valuable adjunct to the treatment of oral mucosal melanoma. 
The prognosis for oral melanoma is extremely poor. A review of the literature indicates that the 5 years survival rate with in a broad range of 4.5-48%, but a large cluster occur at 10-25%.  The site of mucosal origin appears not to influence survival, but younger patients have a better survival than older ones. Patients with nonpigmented or amelanotic lesions particularly show poor prognosis. Patients usually die from distant metastasis rather than from lack of local control. Hemi-maxillectomy or complete maxillectomy is done for lesions that invade the overlying maxillary bone.
Periodic follow-up for oral examination and assessment is necessary to evaluate the recurrence. Recurrence has been reported as long as 11 years after the initial surgery. Early recognition and treatment greatly improve the prognosis. Late discovery and diagnosis often indicate the existence of an extensive tumor with metastasis. After surgical ablation, recurrence and metastasis are frequent events, and most patients die of the disease in 2 years.
| Conclusion|| |
Oral malignant melanoma though an extremely rare is potentially very aggressive malignancy. Clinically these are asymptomatic in their clinical presentation and tend to mislead the clinician as benign lesions. Thus, the importance of early detection and diagnosis that can be life-saving cannot be overemphasized. Early detection of oral melanoma is very critical, which can be achieved by self-examination training and early detection of suspected pigmented lesions by dentist.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]