Noncutaneous melanoma have distinct features from each other and cutaneous melanoma

Compared to the cutaneous melanoma, noncutaneous melanomas are relatively rare and have a distinct pattern of behavior. We performed this study to define the clinical characteristics and outcomes of patients with noncutaneous melanomas and emphasize how they differ from cutaneous melanomas.

216 patients who were diagnosed with noncutaneous melanoma were assessed and their medical records between 2000 and 2010 were retrieved from the cancer registry. 475 patients with cutaneous melanoma were used for comparison.

Of the 216 noncutaneous melanoma patients, 83 had mucosal melanoma, 101 had ocular melanoma and 32 had unknown primaries. For mucosal melanoma, the head and neck was the most common anatomic site (53%), followed by the gastrointestinal tract (37%), female genital (6%) and urinary tract (4%). The majority of the ocular melanomas (94%) originated in the uvea. 32 patients demonstrated a primary unknown disease with regional metastasis as the dominant behavior (72%). Age was found to be statistically significantly different among melanoma patients (p < 0.001). Younger patients had more cutaneous and unknown primary melanomas, whereas older patients had more ocular and mucosal melanoma. In subset analyses, we found significant differences between cutaneous and ocular (p = 0.038) or mucosal (p < 0.001) melanomas. The ratios of metastasis on admission were higher in patients with mucosal (27.7%) and unknown primary (28.1%) melanomas, and lower for ocular (3%) melanomas (p < 0.001). Patients with cutaneous melanoma had an intermediate (12%) ratio. Patients with ocular melanoma had better outcome than patients with other melanoma sites (p < 0.05). While overall survival for cutaneous melanoma was significantly negatively correlated with male gender (p < 0.001), advanced stages (p < 0.001) and old age (p = 0.005), stage IV disease was the only independent prognostic factor in patients with ocular melanoma (p = 0.006). No prognostic factor for outcome was found for either mucosal or unknown primary melanomas.

The clinical presentations and prognoses of different primary sites of melanoma are distinctive. Therefore, approaches to these melanomas should be different.