High frequency, high resolution B-scan ultrasound in the assessment of skin tumours.

Sixteen skin tumours and one BCG vaccination granuloma were examined by 20-MHz B-scan ultrasound. Images were compared with closely matched histological sections of excised lesions. The correlation between histology and ultrasound was excellent for maximum tumour depth measurements (r = 0.96, P < 0.0001), but less good for maximum width (r = 0.84, P < 0.0001) because of the elastic contraction of tissue at excision. Architectural detail of lesions on histological sections corresponded well with that on ultrasound images. There was a good correlation for heterogeneity (collagen distribution vs. echo pattern (r = 0.86, P < 0.0001)), and between collagen content and echogenicity of lesions (r = 0.69, P < 0.003). Strong correlations were also obtained for echogenicity vs. spacing of collagen bundles (r = -0.65, P < 0.005), echogenicity vs. collagen bundle size (r = 0.58, P < 0.02), and echogenicity vs. cellularity (r = -0.68, P < 0.003). Results for dermatofibroma were atypical, due to paradoxical low internal echogenicity and increased echo absorption. B-scanning is a reliable non-invasive method for assessing tumour dimensions, and has potential for the study of tumour characteristics for diagnostic purposes.