Preoperative assessment of skin tumor thickness and structure using 14-MHz ultrasound

The aim of this study was to compare the relationship between skin tumor thickness and homogeneity and to evaluate the accuracy of 14-MHz ultrasound while measuring the thickness of different skin tumors.

The ultrasonographic and histological analysis of 72 skin tumors was performed. Preoperative vertical tumor thickness (T) and structure of 12 melanomas, 34 melanocytic nevi and 26 basal cell carcinomas was assessed by 14-MHz ultrasonography. After the tumors were excised the vertical thickness measurement (Breslow index, pT) was performed by pathologist. According to the histological thickness all skin tumors were divided to thin (≤1mm) and thick (>1mm). The accuracy of the 14-MHz ultrasound measurements and correlation between the ultrasonographic and histological tumor thickness were estimated.

Homogeneous structure was assessed for all thin (≤1mm) and the majority (81.3%) of thick (>1mm) melanocytic skin tumors. Nonhomogeneous structure was estimated in thin and thick basal cell carcinomas, accordingly 42.9% and 31.9%. Measurements of T and pT correlated moderately in thick (>1mm) tumors (r=0.694), while in thin (≤1mm) tumors correlation was low (r=0.336). Moderate correlation between ultrasonographic and histological thickness was computed for melanocytic skin tumors as well as for basal cell carcinomas (r=0.564 and r=0.690).

Medium frequency ultrasound is not a reliable tool for the precise measurement of thin (≤1mm) skin tumors. Ultrasonography using a 14-MHz frequency transducer enables more precisely to measure the thickness of basal cell carcinoma than melanocytic skin tumors. The 14-MHz ultrasound is support tool to suggest the morphologic type of skin tumor.