Focal intravascular coagulation in progressive ascending telangiectasia: ultrastructural studies of ketoconazole-induced involution of vessels.

We describe a unique form of telangiectasia that we have called progressive ascending telangiectasia. It is a noninflammatory process, characterized by the presence of greatly dilated venous capillaries in the upper dermis. By means of scanning electron microscopy, focal fibrin clots were observed in some of the dilated vessels in the skin of a patient with this disease. These were not apparent with either light microscopy or transmission electron microscopy. Immunofluorescent microscopy revealed deposition of complement and IgM in the vessel walls. The endothelial cells showed ultrastructural evidence of heightened metabolic activity (numerous pinocytotic vesicles, increased number and size of mitochondria, convoluted nuclei, and prominent rough endoplasmic reticulum). Around the dilated vessels there was a thick laminar wall of multiple basement membranes embedded in mucopolysaccharide. The electron microscopic appearance of the endothelial cells and their investments showed them to be dilated venous capillary channels. Ketoconazole therapy induced disappearance of many of the dilated vessels within 1 month. After 5 months of this treatment, skin biopsies of the cleared areas showed an absence of dilated vessels. The thick laminar walls and intravascular clots had disappeared. It is postulated that microbially induced focal intravascular coagulation plays a role in the pathogenesis of progressive ascending telangiectasia. Stasis factors would seem to account for the dependent, ascending nature of the loci of coagulation.