[Preoperative ultrasonographic measurement of melanoma thickness with 20 MHz probe]

The authors report on the preoperative evaluation of melanoma thickness with very high frequency US probes (20 MHz). Thirty patients with clinical suspicion of melanoma were examined preoperatively with US. The high quality of the images obtained with 20-MHz US probes allowed the lesions involving the superficial derma or, in more advanced cases, all derma, to be demonstrated and tumor thickness to be measured accurately. The latter is a major prognostic factor and indeed Breslow's classification is based on tumor thickness. The preoperative US study of melanoma thickness allows the surgeon to plan excision depth, which is necessary for accurate and safe tumor resection, that is, whose margins are proportionate to melanoma thickness. In the 30 patients submitted to preoperative US measurements of tumor thickness, US and histologic findings were in agreement. US overestimated melanoma thickness by 7 to 11%, which however had no impact on prognosis and surgical planning. While US can differentiate melanomas from other types of benign or malignant pigmented skin lesions such as blue nevus, pigmented basalioma or pigmented seborroic cheraosis, no unquestionable US signs have been found yet to differentiate melanoma from nevus, which makes US useless for the differential diagnosis. Nonetheless, surgeons can use preoperative US to adapt the exeresis of melanoma to its actual severity and to reduce scars to a minimum. Possible skin metastases can also be detected by US and thus removed.