Detecting melanoma before it becomes invasive

A new dermoscopic feature, irregular hyperpigmented areas, may be the most potent dermoscopic indicator of melanoma in situ (MIS), even when compared with atypical nevi. This feature is one of five indicators of MIS found in a multicenter study of patients with histopathologically diagnosed MIS or other skin tumors. The study appears inJAMA Dermatology.

Investigators led by Aimilios Lallas, Ph.D., from Aristotle University in Greece, assessed the accuracy of known melanoma criteria to diagnose MIS compared with benign pigmented lesions in 1,285 index lesions from 1,285 patients.

The five significant dermoscopic indicators of MIS versus other skin tumors were atypical network, regression of more than 50 percent, irregular hyperpigmented areas, angulated lines, and prominent skin markings. Of these, irregular hyperpigmented areas represented the strongest indicator, with a 5.4-fold probability of MIS when present.

The hyperpigmented areas are dark brown or black small areas seen in the central parts of a lesion. “Their shape is irregular and does not fit with any known geometric shape (eg, triangle, line, square); therefore, they cannot be classified as any other previously known feature (eg, dots, globules, blotches, lines),” the investigators wrote. Irregular hyperpigmented areas are typically smaller, multiple, and “bizarrely outlined” compared with blotch.

“Irregular hyperpigmented areas, prominent skin marking, and angulated lines were more frequent in MIS compared with atypical nevi,” they added. When compared with excised nevi, irregular hyperpigmented areas increased the probability of MIS by 4.3-fold and prominent skin marking by 2.7-fold.

The stated goal of the research was to detect melanoma before it becomes invasive. “These findings might enhance the ability of clinicians to improve their accuracy in recognizing melanoma at the earliest possible stage, lowering the risk of diagnostic delays and the subsequent burden for the patients, clinicians, and health systems,” the authors concluded.

In an editorial published with the study, Nufer et al. wrote that MIS increases the risk of invasive melanoma and several other cancers, but its identification and diagnosis are challenging. The dermoscopic criteria discovered by Lallas and colleagues overcome some of the challenges in early identification but may also lead to detection of clinically indolent lesions and the harms of over diagnosis, they believe.

They support incorporating the dermoscopic criteria into screening programs that address those who would benefit the most.  “The individuals who will benefit most from improved diagnostic accuracy are those with multiple nevi and a personal or family history of melanoma,” they wrote. “It is not feasible from a patient or practical perspective to excise every nevus, so accurate noninvasive diagnostic tools are needed.” They advocate for studies similar to the one by Lallas et al  “to refine and simplify dermoscopic criteria and promote its clinical utility for early melanoma detection.”

Dermoscopy is one tool, but an essential one, in the battle against melanoma, they argue, with others being risk assessment tools, genetic profiling, total body photography.

REFERENCES

Aimilios Lallas, PhD; Caterina Longo, PhD; Marco Manfredini, MD; et al. “Accuracy of Dermoscopic Criteria for the Diagnosis of Melanoma in Situ,” JAMA Dermatology. Published online Feb. 21, 2018.  DOI:10.1001/jamadermatol.2017.6447

Kaitlin L. Nufer, Anthony P. Raphael, PhD; H. Peter Soyer, MD, et al. “Dermoscopy and Overdiagnosis of Melanoma In Situ,” JAMA Dermatology. Feb. 21, 2018. DOI:10.1001/jamadermatol.2017.6448