Primary mucosal melanoma of the oral cavity is an exceedingly rare neoplasm which is estimated to comprise 1-2% of all oral malignancies. In contrast to cutaneous melanomas, the risk factors and pathogenesis are poorly understood. The predominate localization of primary oral melanoma is hard palate and maxillary alveolus. Dermoscopy may be utilized as an adjunctive tool in the clinical differential diagnosis of oral mucosal melanoma whenever the lesion is accessible with a dermoscope. Surgery is the mainstay of treatment, but it may be challenging depending on the location of the tumor within the oral cavity and its size. Adjuvant therapy with dacarbazine, platinum analogs, nitrosoureas and interleukin-2 have been utilized with low response rates. Imatinib may be effective for patients with with c-Kit gene mutations. Sunitinib and dasatinib have been reported effective in selected cases. Vemurafenib and dabrafenib are targeted agents for patients with BRAF mutation-positive melanoma. Ipilimumab, an anti-cytotoxic T-lymphocyte antigen 4 antibody and pembrolizumab, a monoclonal antibody targeting programmed death 1 receptor may be a feasible treatment option in patients with metastatic mucosal melanoma. (J Dermatol Case Rep. 2014; 8(3) Melanoma is a malignant tumor that arises from melanocytes and is most commonly cutaneous in origin. Extracutaneous melanomas are known to be exceedingly rare and aggressive neoplasms that embrace ocular, mucosal and leptomeningeal melanomas.
EpidemiologyMucosal melanomas are estimated to comprise 4-6.8 % of all primary melanomas.
1The incidence rate for mucosal melanoma (MM) is 2.3 per million.
1,2The incidence of MM increases with age. Older patients have tenfold higher incidence of MM compared to patients under the age of 60 years.
2Primary oral mucosal melanoma (POMM) is excessively uncommon in prepubertal children.
3Although there is a slight male preponderance (1.2:1), 1,4 some studies have been reported higher gender distribution of mucosal melanoma for women, 5,6 other indicate that there is no significant difference between sexes in the incidence of this tumor.
2,7The incidence rate of POMM is highest among Asian men. 3,6 Among the Japanese oral melanoma accounts for 7.5 % of all melanomas versus less than 1 % in Caucasians.
8,9Pathogenesis In contrast to cutaneous melanomas, the etiology and pathogenesis of POMM is poorly understood and no etiological and intraoral risk factors, other than preexisting pigmented nevi, have been identified. 10,11 POMM are believed to arise from pigmented nevi, pre-existing pigmented areas or de novo (30% cases) from apparently normal mucosa. 9,12 Although Kahn et al 13 described transformation of a benign oral pigmentation to primary oral melanoma, a definite precursor lesion has not been identified. 14,15 In the oral cavity, mechanical trauma including injury from ill-fitting prostheses, infection, tobacco use has been cited as possible causative factors, but its etiological role seems unlikely.
30Amelanotic oral melanoma is partic...