Structureless light brown areas should be evaluated as a distinct pattern in diagnosing melanoma in situ (MIS), according to study results published in the British Journal of Dermatology.
In this retrospective study to assess the sensitivity of the 3-point and 7-point checklist diagnostic algorithms, researchers selected patients (n=55) undergoing a clinical and digital dermoscopic evaluation from 2016 to 2018. Cutaneous MIS (n=32) and invasive superficial spreading melanomas (SSM, n=25) were excised, and dermoscopic images were evaluated by 3 dermatologists blinded to histopathological diagnosis. Researchers used a chi-squared test to establish the difference in frequency of each dermoscopic finding in MIS and invasive SSM.
The 3-point checklist gave a positive result in 23 lesions, with a sensitivity of 72%; the 7-point checklist gave a positive result in 25 lesions with a sensitivity of 78%. The sensitivity of both the 3-point and 7-point checklists was higher in the SSM group (88% and 92%, respectively). Investigators indicated that the diagnostic sensitivity of the 3-point checklist is 16% lower and of the 7-point checklist is 14% lower for MIS lesions than for invasive SSM lesions. Structureless light brown areas were the dermoscopic finding that occurred mostly in the MIS group with a relative frequency of 75% vs 32% for the invasive SSM group (P =.001).
“We believe that the use of this new dermoscopic pattern as a predictor of MIS can be very useful in everyday clinical practice because light brown structureless areas are very easy to find, in particular for those dermatologists without experience in dermoscopy,” the researchers advised. “By simply adding the presence of structureless light brown areas to both the [7- and 3-point] checklists instead of the blue-white veil and the blue-white structures, their sensitivity increased by 22% in the diagnosis of MIS.” They noted that in the analysis of doubtful melanocytic lesions, the dermatologist can “simply search for a characteristic [color] (light brown), rather than looking for particular signs or patterns.”
Filoni A, Lospalluti L, Zanframundo G, De Marco A, Argenziano G, Bonamonte D. Light brown structureless areas as a predictor of melanoma in situ [published online February 4, 2020]. Br J Dermatol. doi: 10.1111/bjd.18926