ORLANDO Vascular structures visualized on dermoscopy aid in the diagnosis of both benign and malignant nonpigmented tumors of the skin, Dr. Brian Katz said at the annual meeting of the Florida Society of Dermatologic Surgeons.
In fact, associated vasculature should be evaluated carefully to avoid missing a malignancy, said Dr. Katz of Mount Sinai Medical Center, Miami Beach.
When using conventional dermoscopy for nonpigmented lesions, be careful about the amount of pressure applied because a blanching of the vessels can occur and impede diagnostic efforts. Also, consider using ultrasound gel rather than alcohol with dermoscopy, he suggested, because it helps prevent compression of vessels. (See box at right.)
This is important because special morphologic types of vessels are associated with different skin tumors. Various studies show which types of vessels are suggestive of which diagnoses, he said.
In nonpigmented basal cell carcinomas, arborizing vessels are a major feature visualized on dermoscopy, and these were shown in at least one study to have a 90% positive predictive value for basal cell carcinoma. Pink-white to white shiny areas and ulceration also are characteristic in these lesions.
With superficial basal cell carcinoma, two main dermoscopic features typically are observed: shiny pink to white structureless areas and short, fine telangiectasias.
Dr. Katz discussed other types of malignant lesions, along with their associated vasculature on dermoscopy:
PISquamous cell carcinoma in situ/Bowen's disease. These lesions are characterized by glomerular vessels and scaly surface on dermoscopy.
PISquamous cell carcinoma (more invasive types). Characterized by polymorphous vessels, which are mainly glomerular or hairpin vessels and are irregularly distributed and which have a whitish halo.
PIAmelanotic melanoma. Characterized by the presence of mainly dotted and linear irregular polymorphous vessels or by hairpin polymorphous vessels with milky-red globules/areas and ulceration. A whitish-pink background also may be seen on dermoscopy.
A rule of thumb is the more vessels seen, the more likely it is to be a malignant lesion, Dr. Katz said.
Vasculature visualized on dermoscopy is helpful for diagnosing benign nonpigmented lesions, including pyogenic granuloma (characterized by milky red homogenous areas separated with white intersecting lines with a white collarette at the periphery) and intradermal nevi (commalike vessels with a regular distribution throughout the lesion, a pink or pale structureless background, and sometimes pigmentary remnants).
Nonpigmented seborrheic keratosis also can be diagnosed with dermoscopy. It is characterized vascularly by regularly distributed hairpin loop vessels; dermoscopic features of keratinization; and dermoscopic features including comedolike opening, milialike cysts, sharp borders, fissures, and ridges. Yellow scaling and whitish halo also may be noted.
Other benign lesions that can be diagnosed include sebaceous hyperplasiaaggregated white to yellow central globularlike structures and surrounding, scarcely branching crown vessels at the periphery that never cross the center of the neoplasmand Spitz nevus, which is characterized by dotted vessels, regular distribution, and a pink background, Dr. Katz said.
Dermoscopy of a malignant neoplasm reveals multiple arborizing vessels on a pink, whiteshiny background. Courtesy Dr. Brian Katz
Ultrasound Gel a Better Choice in Some Situations
Research on the use of dermoscopy has shown that although alcohol is the "best all around" fluid to use for dermoscopy, ultrasound gel is a better option in some instances, Dr. Katz noted.
For examining melanonychia of the nail plate, gel works best. Similarly, for nonpigmented tumors of the skin, in which visualization of the vasculature is important for making a correct diagnosis, gel helps mitigate the effects of some of the pressure that is applied with conventional contact dermoscopy.
In a comparison of contact dermoscopy with gel versus alcohol for a malignant melanoma, the gel clearly allowed much better visualization of the vasculature, while the alcohol allowed more compressionand thus blanchingof the vessels, he said.
The effect was strictly caused by the pressure applied, he said at the meeting, noting that pressure should be minimal with contact dermoscopy.
An option to circumvent this problem altogether is to use a polarized dermatoscope in noncontact mode, which has been shown to be the best option for visualizing blood vessels, Dr. Katz said.
Dermoscopy with ultrasound gel (left) allows for better visualization than with alcohol (right) because there is less vessel compression. PHOTOS COURTESY DR. HAROLD RABINOVITZ
