Differentiation of common benign pigmented skin lesions from melanoma by high-resolution ultrasound

Background There are potential clinical benefits if non-invasive methods ca n be used to diagnose or exclude melanoma, Objectives We investigated high-resolution ultrasound (HRU) as a potential non-invasive diagnostic aid for pigmented skin lesions, Methods Using a 20-MHz ultrasound B-scan imaging system interfaced to a com puter, we assessed acoustic shadowing and entry echo line enhancement (EEE) for 29 basal cell papillomas (BCPs) and 25 melanomas, Acoustic shadowing w as estimated by the dermal echogenicity ratio (DER), comparing mean echogen icity below the lesion with that of adjacent dermis. Histological features were scored independently, Results DER < 3 correctly distinguished melanoma from BCP with 100% sensiti vity and 79% specificity, Specificity increased to 93% if the presence of E EE was included as a discriminator, Shadowing correlated most significantly with histological extent of hyperkeratosis (P < 0.0001). Consequently, thi s method falsely identified non-keratotic acanthotic BCP (n = 3) as melanom a. Highly significant differences between benign naevi (n = 15) and melanom as (n = 24) were found, The SD of retrolesional echogenicity was higher for naevi than melanomas (P < 0.0001), but such an analysis was poorly specifi c for the diagnosis of melanoma (30%), Conclusions Overall, HRU has considerable potential as a high-performance s creening tool to assist in the discrimination between BCP, but not benign n aevi, and melanoma, In particular, it may be possible to exclude melanoma w ith 100% certainty in the differentiation of BCP from melanoma.