The natural course of cutaneous
melanoma (CM) is determined by its metastatic spread and depends on
tumor thickness, ulceration, gender, localization, and the histologic subtype of the primary
tumor. CM
metastasis develops via three main metastatic pathways and occurs as satellite or in-transit
metastasis, as regional
lymph node metastasis or as distant
metastasis at the time of primary recurrence. About 50% of all CM patients with
tumor progression firstly develop regional
lymph node metastases. In the other 50% the first
metastases are satellite or in-transit
metastases (about 20%), or immediately distant
metastases (about 30%). Development of distant
metastasis appears to be an early event in metastatic spread and may in the majority of cases originate from the primary
tumor, only few cases may develop secondarily to locoregional
metastasis. Reporting of organ involvement in distant
metastasis greatly differs between the results of imaging techniques and autopsy results in respect to the metastatic patterns detected, pointing out that there is a need of improved imaging systems. Proliferation, neovascularization, lymphangiogenesis, invasion, circulation, and
embolism are important steps in the pathogenesis of CM
metastasis, with
tumor vascularity as an important independent significant prognostic factor. The expression of
chemokine receptors in
cancer cells associated with the expression of the respective
chemokine receptor ligands in the target sites of the
metastasis is an interesting observation which may stimulate the development of new therapeutic strategies.