Water-based correction fluid is a useful skin marker for determination of the tumor margin of basal cell carcinoma under high-frequency ultrasound

We propose a new method to determine the appropriate preoperative surgical margin of basal cell carcinoma (BCC) by using water-based correction fluid as a skin marker showing the tumor position on the skin under high-frequency ultrasound (HFUS). After a provisional evaluation by dermoscopy, an approximately 2-mm dot of water-based correction fluid is applied to the tumor margin. The ultrasound waves are blocked by the dot of correction fluid, and a low-signal column is observed under the dot of correction fluid. The dots of correction fluid are moved and located as near as possible to the tumor margin, which is shown as a solid hypoechoic area by the HFUS. After confirming that the dots of correction fluid are applied to the circumferential margin, we draw a line in the gaps between the dots. Before the operation, the dots of correction fluid are removed by forceps, and a line for the tumor margin is drawn where the dots were. The surgical margin is set just outside of this line with the use of a measuring device. Water-based correction fluid is thus a useful skin marker under HFUS to determine the circumferential surgical margin of BCC.