Ranking of 20 MHz sonography of malignant melanoma and pigmented lesions in routine diagnosis.

Purpose: Eleven dermatology clinics from all over Germany took part in our multicenter prospective study with the aim of evaluating 20 MHz sonography in the preoperative diagnosis of malignant melanomas and other pigmented sk in tumours. It was to be assessed how effective sonographic measurement of thickness would compare to histology and the clinical palpation of tumour t hickness and also the significance of differential diagnosis in sonography of malignant melanomas. Method: The prospective multicenter study proceeced as follows. To the end of August 1997 264 patients with a primary malignan t melanoma and 417 patients with benign skin tumours were examined via 20 M Hz sonography. Two different examiners estimated the clinical thickness of the tumour by palpation. The tumour was then excised and examined for posto perative correlation with the histology sections. Results: The final result s showed good correlation between the histological and sonographic estimati on of tumour thickness (r = 0.97). Estimation of tumour thickness by palpat ion showed no correlation with the histology (r = 0.59). Most of the benign (44%) and malignant tumours (38.7%) were spindle shaped. There was no sign ificant difference between the benign and malignant tumour groups in relati on to the sonographic presented shapes or echo signs. No different diagnosi s could be made. Conclusion: The technique of high frequency sonography in relation to preoperative diagnosis of malignant melanomas has high priority . In contrast to clinical estimation of tumour thickness, sonography provid ed a good correlation to histology. The effectiveness of sonography with re gard to the valence of the skin tumours is limited and there is no possibil ity of differentiating between malignant and benign tumours from the morpho logical face value. Hence, there is a demand for developing a 150 MHz appar atus which will be able to supply evidence regarding the valence of skin tu mours.