Clinicopathologic Features and Prognostic Factors in Patients with Non-cutaneous Malignant Melanoma: a Single-center Retrospective Study of 71 Cases

Objectives: This retrospective study was carried out to define the clinical features and prognostic differences in non-cutaneous malignant melanoma (non-CMM) originating from different anatomic sites.

Methods: Clinical and follow-up data for 71 patients with non-CMM were collected and reviewed.

Results: Of the 71 non-CMM patients, 59 were diagnosed with mucosal malignant melanoma (MMM) and 12 with ocular malignant melanoma (OMM). In the 59 MMM patients, the nasal cavity was the most common anatomic site (n = 31, 43.7% of all non-CMM), followed by the oral cavity (n = 9, 12.7%), the genitourinary tract (n = 9, 12.7%), the anorectum (n = 8, 11.3%), and the gastrointestinal tract (n = 2, 2.8%). In the 12 patients with OMM, anatomic sites included the choroid (n = 8, 11.3% of all non-CMM) and the conjunctiva (n = 4, 5.6%). The survival outcome of patients with OMM was much better than that of patients with MMM (P < 0.001). In MMM patients, anorectal melanoma was associated with a worse survival outcome. Age of ≥ 70 years (P < 0.001) and tumor size of > 2 cm (P = 0.02) were significantly poor prognostic factors in MMM. Age (relative risk [RR] 1.068, 95% confidence interval [CI] 1.006-1.133; P = 0.03) and tumor size (RR 1.410, 95% CI 1.038-1.915; P = 0.028) were independent predictors for the postoperative survival of MMM patients. Patients with these two risk factors had a higher risk for recurrence or death (RR 3.107, 95% CI 1.627-5.595).

Conclusions: Our findings demonstrate that prognoses differ in patients with different anatomic sites of primary non-CMM. Advanced age and larger tumor size are the main factors affecting prognosis. Patients with poor risk factors should be treated differently to improve their survival outcome.