[Correlation between epiluminescence microscopy characteristics of malignant melanomas and Clark's level of invasion]

Many epiluminescence microscopy (ELM) characteristics of malignant melanoma support the differential diagnosis of pigmented skin tumors. A preinvasive evaluation of level of invasion would be valuable for planning the excision margins. Since sonography for tumor thickness measurement is rarely available in a practice we searched for specific ELM criteria correlating with Clark's level of invasion. In our retrospective study of 120 malignant melanomas of 30 ELM features were studied for their correlation and the association was significant for 15 features.The following criteria were found only in level III-IV melanomas: intralesional horizontally elongated blood vessels, spontaneous microhemorrhages, plaster-of-Paris-like lacunae, grey-blue/yellowish-brown/reddish saccular pattern and eccentric nodes (reddish, livid, blue). 7 characteristics were predominantly found in level III-IV melanomas and seldom in "thin" melanomas (level I-II): deeply localized gray-blue/-brown fragmentary network, whitish-opaque septa, whitish- or bluish-opaque veil, negative pigmented network, areola with evenly arranged capillaries, polymorphic capillaries. Perivascular melanophages, eccentric dark blotches, pseudotrabeculae of melanophages and greyish-blue annular perifollicular pigmentations were the most significant association of ELM criteria in "thin" melanomas (level I-II). Epiluminescence microscopy is not only a tool for the differentiation of melanocytic lesions but also for a preinvasive evaluation of Clark's level of invasion.