Fig. 1

T-VEC administration. a Fan technique. Enter at a single insertion point as far as the needle allows within the lesion to achieve even and complete dispersion. Inject within the lesion by pulling the needle back without exiting the lesion. Redirect the needle as many times as necessary in the shape of a fan while injecting the remainder of the dose of TVEC. Continue until full administration of vial. b Four quadrant technique. Mark the lesion in four different quadrants 2–3 mm apart. Enter one of the marked areas with the needle and inject virus. Exit the quadrant and move on to different area and repeat in all four quadrants until complete administration of dose. c Clustered dermal metastases. When lesions are clustered together, they can be measured and injected as a single lesion. d Ultrasound. Ultrasound assistance can be used for lesions that are difficult to identify