DERMAL VASCULARITY IN LENTIGO MALIGNA

Lentigo maligna (LM) may represent a tumour arrested in an in situ pha se, lacking the angiogenic capacity and underlying dermal neovasculari zation required for invasive growth. The acquisition of an angiogenic phenotype might be associated with the development of lentigo maligna melanoma (LMM). To investigate this thesis, sections of formalin-fixed , paraffin-embedded tissue from 15 LMMs, and 11 LM excision specimens were stained with the vascular endothelial marker Ulex europaeus agglu tinin I. Dermal vessels were counted and vascular morphometry was perf ormed. In specimens in which LMM was present, dermal vascularity was s ignificantly increased in LM compared with normal skin. The most signi ficant increases were found for dermal vascular density (39 per cent i ncrease, P=0.008) and for total vessel surface area (62 per cent incre ase, P=0.005). However, when no LMM was present, the vascular density underlying LM (79 +/- 9 vessels/mm(2)) did not differ significantly fr om that of adjacent normal skin (67 +/- 6 vessels/mm(2)), although foc al 'hot spots' of increased vascularity were present. We conclude that increased dermal vascularity is present beneath in situ LM and that t his increased vascular density is closely associated with the presence of invasive LMM in the same specimen.