Background: Clinical differential diagnosis between incipient nodular basal carcinoma (NBC) and sebaceous hyperplasia (SH) of the face is difficult in some cases. A comparative histological analysis of these two entities led us to the hypothesis that 20MHz high-resolution ultrasonography (HRUS) may enable differentiation between NBC and SH.
Patients and methods: Seventy-seven facial tumours requiring histological confirmation to distinguish between NBC and SH were scanned using HRUS before excision. No other imaging technique was used. The ultrasound scans were submitted to two blinded reviewers who were asked to classify the ultrasound pictures of the tumours as either hypoechoic or isoechoic/hyperechoic. Hypoechogenicity was defined as a diagnostic criterion for NBC.
Results: Reviewer response reproducibility for 2 images of the same tumour was 90%. Both reviewers agreed regarding the echogenicity classification of an image in 87.4% of cases. The sensitivity of the procedure was 90.9% for detection of NBC and 89.4% for detection of malignant lesions. Specificity was 69.6% for detection of basal cell carcinomas and 78.8% for detection of malignant lesions.
Discussion: HRUS is a non-invasive examination technique with excellent sensitivity for the detection of NBC in differential diagnosis with SH. Hypoechogenicity is not specific to NBC. The sensitivity of HRUS in our study suffered as a result of ultrasonography difficulties regarding unexpected differential diagnoses of NBC as well as tumour localisation in seborrhoeic areas.
Keywords: Carcinome basocellulaire nodulaire; Echogenicity; High-resolution ultrasound; Hyperplasie sébacée; Nodular basal cell carcinoma; Sebaceous hyperplasia; Échographie cutanée haute résolution; Échogénicité.
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