Accuracy of clinical skin tumour diagnosis in a dermatological setting.

The aim of this study was to evaluate the accuracy of preoperative diagnosis of skin tumours in a dermatological setting. Patients undergoing skin surgery at the Department of Dermatology without preoperative biopsy were prospectively enrolled. Preoperatively, a single clinical diagnosis was registered. The histopathological diagnosis, performed after excision, was registered as the correct diagnosis. The sensitivity and positive predictive value of the clinical diagnosis were calculated. A total of 2,953 tumours were included. Altogether, 55.1% of the excised lesions were malignant. Excision margins for malignant tumours were free from tumour cells in 96.0% of cases. The sensitivity for diagnosis of malignant tumour was 98.0% and the positive predictive value was 85.3%. In line with previous studies, the sensitivity and positive predictive value were highest for basal cell carcinoma, 95.4% and 85.9%, respectively. For squamous cell carcinoma, the corresponding values were 68.0% and 67.3%, and for melanoma, 70.6% and 51.3%.