|Year : 2015 | Volume
| Issue : 2 | Page : 145-147
Oral malignant melanoma: A rare malignancy
LS Vagish Kumar
Department of Oral Medicine and Radiology, Yenepoya Dental College and Hospital, Yenepoya Research Centre, Yenepoya University, Mangalore, Karnataka
|Date of Web Publication||16-Mar-2015|
L S Vagish Kumar
Department of Oral Medicine and Radiology, Yenepoya Dental College and Hospital, Yenepoya Research Centre, Yenepoya University, Mangalore - 575 018, Karnataka
Source of Support: None, Conflict of Interest: None
Primary malignant melanoma of the oral cavity is a rare neoplasm. It is very rare aggressive neoplasm arising from a benign melanocytic lesion or de novo from melanocytes within normal skin or mucosa. It is deadly, biologically unpredictable with worst prognosis. These tumors tend to metastasize or locally invade tissue more readily than other malignant tumors in the oral region. The survival of patients with mucosal melanomas is less than for those with cutaneous melanomas. Tumor size and metastases are related to the prognosis of the disease. Early detection, therefore, is important. The paper presents such a rare case that occurred in a young patient.
Keywords: Melanocytes, oral malignant melanoma, pigmented areas
|How to cite this article:|
Vagish Kumar L S. Oral malignant melanoma: A rare malignancy. CHRISMED J Health Res 2015;2:145-7
| Introduction|| |
Melanoma is a malignant neoplasm comprising of melanocytes, which are derived from the neural crest cells that constitute the melanin pigment of the basal layer of the epithelium.  They are biologically aggressive and extremely rare lesions that occur commonly in the maxillary gingiva, more frequently on the palate with few incidences in the mandibular gingiva. 
| Case Report|| |
A 27-year-old male presented with chief complaint of growth in oral cavity. Patient gives history of swelling since 6 months, which gradually increased from peanut size up to its present size. Presenting complaints were bleeding from gums on brushing, tooth mobilty and symptoms of fatigue and headache. Paresthesia was absent. Extraoral examination revealed enlargement of bilateral submandibular lymph nodes, which were non- tender, firm and fixed to underlying tissues. Intraoral examination showed an exophytic growth of 2.5 × 8 cm approximately on the buccal aspect of 31 to 47. The growth was sessile, arising from attached marginal gingiva. It was blackish brown with intense melanin pigmentation [Figure 1]. Exophytic growth was also seen on the lingual aspect of 42 to 47, and appeared to be sessile with brownish pink pigmentation [Figure 2]. The growth was firm, non-tender and no hemorrhage observed. The alveolar segment associated with the growth was mobile on palpation. An incisional biopsy was performed and sent for histological investigation. Histopathological studies (×10) with hematoxylin and eosin stain showed numerous atypical melanocytes within the epithelium with invasion into the connective tissue. These cells were epitheloid to spindle in shape, with vesicular, hyperchromatic nuclei, and prominent nucleoli. Mitotic figures were also observed [Figure 3]. Characteristic clinical and histological features suggested the diagnosis of oral malignant melanoma. The patient was referred to oral surgeon and oncology specialist for further assessment and treatment. Fine-needle aspiration cytology proved infiltration of melanoma cells in bilateral submandibular lymph nodes. However, radiograph of chest and long bones, computed tomography, magnetic resonance imaging and sonography of neck and abdomen were normal and thus ruled out the possibility of metastasis. The physician reported that patient was not willing for treatment and had not reported for follow-up.
|Figure 1: Intraoral growth on buccal gingiva of mandibular right quadrant|
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|Figure 2: Intraoral growth on lingual gingiva of mandibular right quadrant|
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|Figure 3: Histopathology (x10) with hematoxylin and eosin stain showing spindle shaped melanocytes|
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| Discussion|| |
Oral malignant melanomas are clinically asymptomatic in the early stages and usually present merely as a hyperpigmented patch on the gingival surface. Usually the age of onset is 40-70 years and has slight male prediction. They account for 1-2% of all oral malignancies.  Etiology of melanoma is still elusive. UV radiation, exposure to chemicals, presence of nevi, immunosuppression, skin and hair color, genetic factors etc., are thought to be responsible. Oral melanomas are thought to arise de novo. They can also originate from nevus and pre-existing pigmented areas. Genes such as CDKN2A (p16), RB1, CDKN2A (p19), PTEN/MMAC1 are also implicated in the genesis of oral melanoma. They may occur with or without a radial growth phase. In our case, multiple factors such as exposure to sunlight for long duration, possible suppression of immunity due to stress, increased pigmentation of skin and mucosa might have contributed to evolution of melanoma. It might have arised de novo.
Tumors may appear as black, gray, purple, light to dark brown, blue or even reddish with size more than 6 mm, smooth or elevated lesion.  While some lesions are uniform in color, others exhibit marked variation. The lesions are asymmetric, irregular in outline, and occasionally multiple. Symptoms may include swelling, ulceration, pigmentation, discomfort, painful sensation, bleeding, ill-fitting dentures, and any combination of these symptoms. The surface architecture ranges from macular to ulcerated and nodular. The tumor causes extensive destruction of the underlying bone in 78% of cases. The patient's attention may be drawn to the lesion by the presence of a swelling or mass, especially in a pigmented area, possible interference with the fitting of dentures, bleeding, and loosening of teeth.  Regional lymphadenopathy may be present as in our case and this indicates a poor prognosis. Our case exhibited signs and symptoms like enlarging, swelling, pigmentation, mobility of the teeth and alveolar segment. Mucosal melanoma behavior, treatment and prognosis are different from cutaneous melanoma. The prognosis for patients with oral melanoma is much worse than for those with cutaneous lesions. The 5-year survival rate is reported to be 0-50%. ,
Differntial diagnosis includes melanocytic nevi, oral melanotic macule, Peutz-Jeghers syndrome, Addison's disease, Cushings syndrome, melanoplakia, Kaposis sarcoma. Our patient did not have any of the signs and symptoms of above diseases and complete blood investigation was normal leading to exclusion of any systemic disease.
Mucosal melanomas, basically show two histopathological patterns - in situ and invasive. Tumor is limited to epithelium and junctional epithelium in in situ type. Invasion into connective tissue is present in invasive type. In our case, it was a combination of invasive and in situ pattern. This pattern is typical of advanced lesions. Malignant cells exhibit different shapes such as spindle, plasmocytoid, clear cell, and epithelioid. Considerable pleomorphism with large, irregular hyperchromatic nuclei, prominent nucleoli, readily detectable mitotic activity are detected in these cells. Usually oral malignant melanoma can be diagnosed accurately on hematoxylin and eosin-stained sections. However, if pigment is completely absent such as in amelanotic melanoma, immunohistochemical stains are of significant help. Useful markers include S-100 protein, gp 100 (HMB-45), Mart-1 (Melan-A) and antityrosinase. Special stains like Mason's Fontana and melanin bleach are also helpful in diagnosis.
Clinical staging of oral melanoma is by TNM staging (T-primary tumor size, N-regional lymph node metastasis, M-distant metastasis).
- Stage I- Primary tumor present only (Tany N0M0)
- Level I- Pure in situ melanoma without evidence of invasion or in situ melanoma with "microinvasion"
- Level II- Invasion up to the lamina propria
- Level III- Deep skeletal tissue invasion into skeletal muscle, bone or cartilage.
- Stage II- Tumor metastatic to regional lymph nodes (Tany N1M0)
- Stage III- Tumor metastatic to distant sites (Tany Nany M1).
In this case, the clinical staging coincided with Stage II of TNM, which indicates poor prognosis. The careful clinical and histopathological findings lead to the final diagnosis or oral malignant melanoma.Tumor is characterized by marked aggressive and invasive behavior that manifests by both local and distant metastases to sites such as lungs, liver, brain, and bones. Lymphatic metastasis at the time of diagnosis seems to be a crucial prognostic factor for oral melanomas.  Any pigmented lesions in the high-risk regions, such as palate and gingiva should invoke high suspicion of oral melanoma. Surgery is the main line of treatment and is administered in conjunction with chemotherapy, radiotherapy and immunotherapy.  Chemotherapy includes administration of dimethyl trieazenomidazol carboxamide, nimustin hydrochloride and vincristine. Radiotherapy is associated with prolonged remission.
| Conclusions|| |
Occurrence of malignant melanoma in young patients and particularly in oral cavity is very rare. Occurrence in mandible is rarest. This case shows that though cases may seem innocuous initially, this lesion is highly aggressive in nature. Hence, early diagnosis is very important and critical for better survival and prognosis in oral melanoma. Hence, every medical and dental practitioner should be aware of this rare entity.
| References|| |
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[Figure 1], [Figure 2], [Figure 3]