Metastatic patterns and metastatic sites in mucosal melanoma: a retrospective study

Melanomas arising from mucosa are rare and associated with a poor prognosis. This study aims to provide an analysis of metastatic pathways, time intervals, factors influencing metastatic spread and organs for distant metastases.

A total of 116 patients with mucosal melanomas of different sites were included. The mean follow-up interval was 47 ± 52 months. Patients were assigned to two different metastatic pathways, either presenting loco-regional lymph node metastases as first spread or direct distant metastases. The distribution of distant metastases was assessed.

Twenty-six patients presented with a pre-existing metastatic spread and were not assigned to pathways. Of the included patients, 44 developed metastases after treatment of the primary tumour; 25 patients directly developed distant metastases; 16 patients developed regional lymph node metastases prior to distant metastases. Location of the primary tumour in the upper airway or GI tract and advanced T stage were significant risk factors of direct distant metastases. Distant metastases are mainly located in the lung, the liver and non-regional lymph nodes.

Mucosal melanomas show a high rate of direct distant metastases rather than regional lymph node metastases. Thus the follow-up should always include a whole-body cross-sectional imaging in high-risk tumours.

• Mucosal melanomas show a high rate of direct distant metastases. • T stage and primary location are predictors for direct distant metastases. • Distant metastases were mainly found in lung, liver and lymph nodes. • Follow-up of a high-risk mucosal melanoma should include whole-body imaging.