INCORPORATION OF PREEXISTING COLLAGEN BUNDLES IN PRIMARY CUTANEOUS MELANOMA

In a previous qualitative study it has been shown that the incorporati on of pre-existing collagen bundles from the reticular dermis into the bulk of melanoma lesions metastatic to the skin indicates rapid syste mic spread. In the present study the amount of pre-existing dermal col lagen in the bulk of the melanoma lesions in 267 cases of primary mela noma of the skin with a Clark level of at least III was quantitatively assessed using automated image analysis based on RGB (red, green and blue) colour images of sections stained with haematoxylin and eosin. T here was a weak correlation between the amount of pre-existing collage n and the Clark level and the Breslow index. With regard to prognosis, a large amount of pre-existing collagen (>0.13 mm(2) per index slide) was significantly associated with a particularly poor outcome (24-mon th survival rate: 71 +/- 17% compared with 96 +/- 2%; log rank test: P < 0.001). It is clear that a large amount of pre-existing collagen bu ndles occurring as a particular feature of tumour-stroma interaction i ndicates high metastatic capacity in primary malignant melanoma. (C) 1 998 Lippincott-Raven Publishers.