Authored by: Ralph P. Braun
Hairpin VesselsThis glossary term has not yet been described. Hairpin vesselsThis glossary term has not yet been described. are characterized by vessels that resemble hairpins, consisting of a U-shape with a sharp bend at one end. These looped hairpin vessels can appear distorted when the hairpin configuration twists around its own axis. Hairpin vessels are found in melanocyticThis glossary term has not yet been described. and nonmelanocyticThis glossary term has not yet been described. tumors. Relatively thin, uniform hairpin vessels are often seen in keratinizing tumors, such as seborrheic keratosesThis glossary term has not yet been described. (SKs). In these benignis any condition that is harmless in the long run keratinizing tumors, a whitish halo often surrounds the vessels. This whitish halo probably represents viable tumor keratinocytes surrounding the dermal papilla, which contains the hairpin vessel. In a study of pigmented SKs, hairpin vessels were seen in 63% of lesions; more specifically, these vessels were seen in 50% of plaque-type SKs and 43% of papular/nodular SKs but were only seen in 6% of patch type SKs (Braun et al., 2002). In another study looking at lesions with vascular dermoThis glossary term has not yet been described.- scopic structuresThis glossary term has not yet been described., 51.2% of SKs contained hairpin vessels, conferring a PPV of 70%. In keratoacanthomas, hairpin vessels are located peripherally, with a yellow keratotic center. In contrast, hairpin vessels in melanomas are often sur- rounded by a pink halo. Hairpin vessels may also be observed in wartsThis glossary term has not yet been described., SCCs, BCCs, dermal neviThis glossary term has not yet been described., and Spitz neviThis glossary term has not yet been described..