Inconsistencies with dermoscopic diagnoses present challenges

July 1, 2011

Many dermatologists' comfort level with dermoscopy is growing, but dermatologists and dermatopathologists don't always agree on the diagnosis of a particular lesion.

Key Points

Miami - Many dermatologists' comfort level with dermoscopy is growing, but dermatologists and dermatopathologists don't always agree on the diagnosis of a particular lesion.

Such moles can also be difficult even for pathologists to diagnose accurately, he says. He is director, Melanoma Program, Sylvester Comprehensive Cancer Center, and professor, department of dermatology, University of Miami Miller School of Medicine.

"Benign lesions tend to grow in certain patterns, and malignant lesions tend to grow in certain patterns. In the early growth stages, some of these patterns may overlap. As you educate yourself about how to use dermoscopy, you'll learn patterns and become more comfortable with the challenges of differentiating some of these early lesions," he says.

Dr. Grichnik says it's important to remember that "very early melanomas may not have developed worrisome features. In other words, you may be looking at a spot that didn't look that scary" clinically or dermoscopically, yet it was diagnosed as melanoma by a pathologist.

A major reason that this can happen is that the classic ABCD (asymmetry, border irregularity, color, diameter) features actually appear later in melanoma development, he says. "When a melanoma is just beginning to develop, it may be small and uniform, and then due to underlying genomic instability and continued growth, the ABCD features begin to develop."

Conversely, he says that a benign lesion early in its growth phase may look worrisome to a dermatopathologist; nevertheless, it could end up being benign.

"When a lesion is growing quickly, a pathologist may see pagetoid spread, some proliferation or other features that make the pathologist worry that the lesion may be a melanoma. But ultimately, if left in place, some of those lesions may end up senescing and being benign," Dr. Grichnik says.

Balancing act

Ultimately, Dr. Grichnik says it's crucial to balance one's clinical impression with the conclusions of a pathologist.

"We're getting to the point where some of us who see these lesions repeatedly are getting pretty confident in our ability to diagnose melanomas" via dermoscopy, particularly when combined with knowledge of change from total body photos, he says. "As you go through daily practice, you become educated as to what the common benign and malignant patterns look like."

When a dermatopathologist has a different opinion, "It's important for us as dermatologists to sit down with the dermatopathologist and balance what we know about the biology of the lesion with what the dermatopathologist sees," Dr. Grichnik says. "It is important not to dismiss our clinical judgment and assume that what the dermatopathologist says on first pass is the absolute truth. Pathologic review may have missed an important part of the lesion, or perhaps under- or overinterpreted some of the features, or due to the stage of the lesion some features may not be fully developed."