Various distinctive vascular structures can be recognized when performing dermoscopy. These vascular structures have been originally classified by Kreusch and Koch [Hautarzt 1996] and recently modified by Argenziano et al. [J Am Acad Dermatol 1999] as outlined in the following table. For viewing vascular structures it is crucial to use only little compression of the tumor.

Vascular structures Diagnostic significance
Comma vessels Mainly in melanocytic nevi, especially in dermal nevi; rarely in melanomas
Wreath vessels Exclusively in sebaceous hyperplasias
Arborizing vessels Commonly in basal cell carcinomas; rarely in nevi and melanomas and also in seborrheic keratoses
Hairpin vessels Commonly in melanomas and seborrheic keratoses; sometimes also in basal cell carcinomas, keratoacanthomas and in melanocytic nevi
Dotted vessels More or less common in all types of melanocytic tumors; sometimes also in seborrheic keratoses; rarely in basal-cell carcinomas
Linear irregular vessels Relatively common in melanomas, especially when thicker than 0.75 mm; rare in melanocytic nevi
Vessels within regression structures Frequently within white areas of regressive melanomas