Extravascular Tissue Factors in Purpura.

Study of the extravascular tissue factors contributing to purpuric manifestations of dermatoses might be of some help in their understanding, and could give hints of differential diagnostic importance. The various macroscopic and microscopic tissue factors contributing to the manifestations of dermatological purpuras are reviewed. While the importance of the vessel fragility factor is often stressed when the pathogenesis of dermatological purpuras is considered, the extravascular tissue factor is very often neglected. Although this tissue fragility factor is intimately bound up with the vessel fragility factor, one should strive to dissociate the two. Intracutaneous injections of the patient's own blood or of dye solutions may be of help in doing so. [ABSTRACT FROM AUTHOR]