Author(s) : Pascale Quatresooz, Claudine Pierard-Franchimont, Philippe Paquet, Gérald E Pierard , Department of Dermatopathology, University Hospital of Liège, B-4000 Liège, Belgium.
Summary : 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.
Figure 1A, B) Fast-growing MM showing a pink
to red hue.
Figure 2 CIELAB determination. Number of pixels
characterized by given values of the colorimetric values in the
fast-growing MM (straight line) and the surrounding non-neoplastic
skin (dotted line). A, B) 2 examples of value L*. C,
D) 2 examples of value a*.
Figure 3 Angiotropism and micrometastases in the
vicinity of fast-growing MM. A) Single row (or sheath) of MM
cells abutted to a small vascular channel. B) Clusters of MM
cells in close vicinity of vessels.
Figure 4 MIB/Ki67 immunostaining of a fast-growing
MM revealing the large expansion of the neoplastic growth
fraction.
Figure 5 Values of the fractal dimension of the MM
advancing edge in 2 series of fast-growing MM showing or not
angiotropism (circular: individual values, lozenge: median values).
The difference between the 2 groups is statistically significant (p
< 0.05).
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