Etiology • Unknown • Cutaneous malignant melanoma with relation to sun exposure
or familial-dysplastic melanocytic lesions
Clinical Presentation • Rare in oral cavity (< 1% of all melanomas) and sinonasal tract • Most cases occur in those older than 30 years of age. • Usually arises on maxillary gingiva and hard palate • May exhibit early in situ phase: a macular, pigmented patch
with irregular borders • Progression to deeply pigmented, nodular quality with ulceration • May arise de novo as a pigmented or amelanotic nodule • Rarely may be metastatic to the oral cavity as a nodular, usually
pigmented mass
or familial-dysplastic melanocytic lesions
Clinical Presentation • Rare in oral cavity (< 1% of all melanomas) and sinonasal tract • Most cases occur in those older than 30 years of age. • Usually arises on maxillary gingiva and hard palate • May exhibit early in situ phase: a macular, pigmented patch
with irregular borders • Progression to deeply pigmented, nodular quality with ulceration • May arise de novo as a pigmented or amelanotic nodule • Rarely may be metastatic to the oral cavity as a nodular, usually
pigmented mass
Microscopic Findings • Early stage: atypical melanocytes at epithelial–connective tissue
interface, occasionally with intraepithelial spread • Later infiltration into lamina propria and muscle • Strict correlation to cutaneous malignant melanoma is not well
established, although, as in skin, a similar horizontal or in situ growth phase often precedes the vertical invasive phase.
• Amelanotic forms may require use of immunohistochemical identification: S-100 protein, HMB-45, Melan-A expression
Diagnosis • Biopsy • High index of suspicion
Differential Diagnosis • Mucosal nevus • Extrinsic pigmentation • Melanoacanthoma • Kaposi’s sarcoma • Vascular malformation • Amalgam tattoo • Mucosal melanotic macule
Treatment • Surgical excision
Pigmentary Disorders 123
• Marginal parameters related to depth of invasion and presence of lateral growth
• Wide surgical margins; resection (including maxillectomy) for large, deeper lesions
• Neck dissection in cases of deep invasion (< 1.25 mm)
Prognosis • Generally poor for most oral malignant melanomas • Less than 20% survival at 5 years in most studies