Feedback AAD 2017

Dermatoscopic Pearls

How can you maximize the information obtained through your dermatoscope? Ashfaq Marghoob, MD, attending physician at Sloan-Kettering Cancer Center, New York, New York, USA shared 7 tricks and tips for using dermoscopy for the best conclusion.

#1: How tape may prevent a biopsy

On dermoscopy, dots and blotches (lamella) with atypical distribution can suggest malignancies. However, transient dots and blotches can also appear after ultraviolet (UV) exposure, and reflect accumulation of melanin in the stratum corneum. These transient dots and blotches can appear within a few weeks of exposure, and may resolve on their own in about 6 to 10 weeks. In malignant melanoma, however, there is melanin accumulation in all layers of the epidermis, and these dots and blotches do not disappear. Using tape to strip off the upper layer of the epidermis over the lesion can help distinguish transient dots and blotches from more permanent and concerning ones. If pigmentation is just in the stratum corneum, you can strip it off. But you will not be able to strip off a true blotch.

#2: How can a pen help you differentiate ridges and valleys (dermatoglyphics)

Why is it so important to differentiate between ridges and valleys in the palms of the hands and the soles of the feet? Nevi tend to cluster around the meaty ridge associated with the sulcus, and transfer their melanin into the adjacent keratinocytes underneath the furrow. In contrast, melanoma tends to cluster around the eccrine openings and transfer its melanin up to the adjacent keratinocytes, moving upward. Thus, one sees pigmentation on the ridge for melanoma, and in the furrow for a nevus. Dermoscopically, it can be a challenge to distinguish between the ridge and the furrow. Performing a furrow ink test, typically with a gentian ink surgical marking pen, can help overcome this challenge, by highlighting the ridges and eccrine openings, and making it easier to determine whether pigmentation is located in the ridges or furrows.

#3: Dynamic dermoscopy

Applying horizontal pressure to move the skin back and forth can be helpful in determining what is occurring within a lesion. On non-weight-bearing portions of the sole, melanin normally accumulates in a linear pattern that is recognizable as benign. In weight-bearing areas, however, friction may result in slanting of pigmentation across the stratum corneum. As a result, it may be difficult to distinguish dermoscopically between a benign fibrillar pattern and a malignant one in these areas.

Pushing back and forth horizontally with the dermatoscope can help the operator determine whether the pigmentation is actually in a straight, linear pattern or is irregular. This technique is referred to as oblique dermoscopy.

#4: Harnessing the power of the smartphone camera to better visualize dermoscopic structures

Many smartphone cameras have a HDR (high dynamic range) feature, which can enhance the results of dermoscopy. Taking a picture with HDR creates multiple images at different exposures, which are then combined, providing better visualization of structures that might be seen better in one exposure or the other. These images provide a clearer visualization of blood vessels and other structures of a lesion.

#5: Use a pen to highlight the 3rd dimension

A potential limitation of dermoscopy is that it captures 3-dimensional structures in 2 dimensions, potentially failing to capture structures or characteristics that can be seen with the eye using side lighting or by touching the lesion. It may be challenging to see all the structures within common lesions like seborrheic keratosis, causing them to appear featureless and structure-less under dermoscopy, and thus more similar in appearance to malignant melanoma. Using a gentian violet surgical marking pen to highlight the lesion can make 3-dimensional structures such as comedolike openings and cerebriform structures more visible. This technique may also be useful in examining common pink-colored lesions on the extremities characterized by dotted vessels or glomerular vessels, which may resemble squamous cell carcinoma when viewed through a dermascope. The appearance of cornoid lamella when highlighted by gentian violet can identify this type of lesion as a porokeratosis that does not require biopsy.

#6: In the right light at the right time, everything is extraordinary

Standard light dermoscopy and polarized light dermoscopy provide complementary information, with some features being more visible with one type of light than the other.

Standard light is better for visualizing the uppermost layers of the skin, and thus is useful for visualizing blue white veil associated with orthokeratosis, granularity associated with regression structures, comedo-like openings, and millia-like cysts. On the other hand, polarized light highlights deeper structures better, and is superior for visualization of blood vessels and stromal alterations, which appear as shiny white lines. Hybrid dermatoscopes allow the operator to toggle between standard and polarized light; this can create a blinking effect (“blink sign”) for structures that are more visible with one type of light.

#7: Lesions that wobble vs slide (on horizontal dermoscopy)

Moving the lesion back and forth horizontally, and evaluating whether the entire lesion wobbles back and forth or slides, can help distinguish between dermal processes and more superficial lesions.