Live Blog: Pigmented Lesions – Faculty: Whitney High, MD
In this live blog from the Annual Summer SDPA Conference in Las Vegas, Whitney High, MD, presented a lecture on “Pigmented Lesions.” Here are some of the highlights.
Dr. High approached his lecture on pigmented lesions through a histological approach and started with some basics.
Melanocytes are considered “genetic defenders.” They are located along the dermoepidermal junction and produce melanin (pigment). That melanin absorbs the energy of ultraviolet light, which protects DNA. Everyone has about the same number of these in their skin. A nevus, or mole, appears on the skin when melanocytes nest together. Dr. High explained that, “Melanoma is when good melanocytes go bad.” He continued, “It’s the same exact cell but no longer playing nicely with its neighbors.”
Melanoma is appearing in our clinics more and more as years go on. In repeated studies using insurer data, Melanoma is the cancer most likely to lead to litigation against derm professionals. So how do we find it clinically and how do we see it histologically? Dr. High stressed, “There’s nothing that I can do to absolutely, 100% prove that what I am seeing is a melanoma.” However he gave some tips that help him provide his best-supported opinion.
Tip #1: ABCDE
Look for the ABCDEs during clinical examination to rule out melanoma. Those are: Assymmetry, Border irregularity, Color Variegation, Diameter > 6 mm, Evolution.
Tip #2: Note Atypical Nevi
In repeated epidemiologic studies, atypical nevi are a marker for people at risk for melanoma. The more atypical nevi you have, the higher your risk for melanoma.
Atypical nevi may also be a precursor lesion for melanoma. Someone with more than 50 dysplastic nevi and a family history of melanoma is 500x at risk above the general population.
Tip #3: Understand Stains
S-100: In melanocytic neoplasms it is expressed by 98% of melanomas and in 95% of desmoplastic MM.
P16: A good discriminator for melanoma. In a 2010 study, it proved to be better than E-cadherin and cyclin D1
HMB 45: Look for a zoned pattern. A malignant melanoma will retain the color of the stain.
Tip #4: Know What’s Not Melanoma
Blue Nevi are not melanoma and are related to other pigmentary disorders: Mongolian spot, nevus of ito, nevus of ota. They are dermal spindled melanocytes that produce melanin.
Cellular blue nevi may have elevated risk of degeneration, particular concern on the scalp of older persons. With these, just pause and think: Will my sample be good? Should I just cut this out? Dr. High says, “If it’s cheap real estate like on the back of the patient, just get rid of it!”
Clonal Nevi resemble a fried eye, with the darker part being caused by a hyperpigmented clone. “I just go ahead and cut these out,” says High.
The Deep Penetrating Nevus is often mistaken for melanoma. They look scary because they push down under the skin. “For the sake of your patient either cut it out or don’t sample it at all,” says High.
Spitz Nevi look like melanoma but these are mainly showing up on young patients who have a 100% survival rate. Dr. High uses the “All of Nothing” rule here. “Play the odds of age when it comes to spitz nevi. They’re common in children, not as common in adults. So if you are going to call something melanoma in a child, it better have all the criteria for melanoma. If you have a 55 year old with a spitz, that better have ALL the features of a spitz nevus.”
Dr. High confessed that when it comes to dermatolopathology, “I wish I had a Magic 8 ball that could tell me what to do.” But since those don’t exist all he can do is remind us that “dermatopathologists can only give you their opinion.”