Primary Malignant Mucosal Melanoma-In the Oral Cavity

BACKGROUND: Primary oral mucosal melanomas (OMM) of the head and neck are rare. In contrast to the relatively good prognosis of early skin melanoma, and despite the implementation of aggressive treatment, the prognosis of oral melanoma is extremely poor.METHODS AND MATERIALS: We retrospectively analyzed 16 patients with primary melanomas of the oral cavity between 1986 and 2012 in Chang Gung Memorial Hospital, Linkou.RESULTS: A slight male predominance was found (M : F = 1.67 : 1), and the mean age of the patients was 63 years (range: 31 to 91 years). The most common sites of OMM were in the hard palate (7/16, 43.8%) and alveolar ridge (6/16, 37.5%). The stage distribution was 4 (25.0%) in stage III, 11 (68.8%) in stage IVa and 1 in stage IVc (6.3%). In 9 patients who received radical surgery with neck dissection, 8 patients (88.9%) had lymph node metastasis. In 7 patients who were clinically negative for neck lymph node metastasis, 6 patients (85.7%) were found to have occult neck metastasis. The most common metastatic lymph nodes for therapeutic neck dissections were in level II (6/9, 66.7%). Distant metastasis was found in 9/16 (56.3%) of the cases during follow-up. The main cause of death from OMM was distant metastasis. The 5-year overall survival rate of primary OMM was 31.3% in our patients..CONCLUSIONS: We found a high incidence of neck lymph node metastasis in OMM. The development of distant metastasis after treatment was more frequent than local failure. The prognosis of OMM was poor even after radical surgery and adjuvant treatment.