Angiogenic fast-growing melanomas and their micrometastases

Malignant melanoma (MM), particularly its fast-growing type, is prone to interstitial, intravascular and extravascular migratory metastases. There is no information linking their growth fraction, the configuration of the MM advancing edge, the extent in vascularity and the propensity to metastatic progression. The objective of this study was to determine the growth fraction, the size of vascularity and the contours of the progression border of 32 fast-growing MM with regard to the presence or absence of a micrometastatic spread inside the skin and overt metastases in the sentinel lymph nodes. In vivo high resolution colorimetry was performed as a clinical estimate of MM vascularity. Euclidean geometry and fractal analysis were used on immunohistochemical sections. The relative microvasculature profile area beneath MM, and the fractal dimension D of the MM frontline were assessed. The MIB/Ki-67 index was determined in MM cells. Value a* of colorimetry was similarly increased in the presence or absence of micro-metastases. No difference in growth fraction was revealed between these neoplasms. Correlations were found between vascularity and angiotropism, and between the micrometastatic process and the sentinel lymph node involvement. By contrast, no correlation was shown between vascularity and the fractal D dimension of the MM advancing edge. In sum, this study establishes a link between the extent of MM growth fraction, vascularity and the presence of dermal and nodal micrometastases in fast-growing MM.