Dermatology Coding Alert

Question: If our surgeon removes a sebaceous cyst from the back that measures 2.5 x 1.75 x 0.5 cm, should we add up all the dimensions or should we just use the biggest dimension of 2.5? Is the answer the same if this were a tumor instead of a cyst?

Kansas Subscriber

Answer: Whether the surgeon removes a benign or malignant lesion, you should calculate the size for coding purposes as the largest lesion diameter plus two times the narrowest margin. You should not add up the dimensions or use only the largest dimension if the surgeon properly documents the case. The measuring method for lesion excision coding doesn't vary based on "tumor instead of cyst."

In the example you give, the surgeon reported only the lesion size, not the margin. If that's all the information you have,you'll have to report the service based solely on the largest lesion diameter -- 2.5 cm, which reports to 11403 (Excision, benign lesion including margins, except skin tag [unless listed elsewhere], trunk arms or legs; excised diameter 2.1 to 3.0 cm).

If your surgeon had documented the margins -- 0.5 cm at the narrowest, for instance -- you could calculate the size as 3.5 cm. That would code to 11404 (... excised diameter 3.1 to 4.0). If you're not adding in the margins for lesion excisions you're leaving money on the table.