Dermatology Coding Alert

Question: When a physician states that the lesion/cyst/mass excised from the skin or subcutaneous tissue was 3 x 3 x 2 cm, how do you choose the size for coding? The surgeon didn't break out the size of the lesion or the margin. He only states the dimensions. Would I code this as a 3 cm, 5 cm, or 8 cm excision?

Michigan Subscriber

Answer: In this case, you can bill only for the 3 cm lesion excision, based on location and malignancy, since your physician did not provide sufficient documentation to code any other code. For example, if the surgeon removed a benign lesion from the patient's upper arm, you would report 11403 (Excision, benign lesion including margins, except skin tag [unless listed elsewhere], trunk, arms or legs; excised diameter 2.1 to 3.0 cm).

How it works: The size of the lesion for coding purposes is the largest diameter of the lesion (in this case, 3 cm) plus the smallest margin multiplied by 2. When the physician doesn't document the smallest margin, you cannot consider the size of the margin as part of the final size of the excision.

In this case, if the physician took a 1 cm margin around the 3 cm lesion, the total excision would be 5 cm  (3 cm lesion plus 1 cm margin x 2). But since you don't have that documentation, you can bill only for a 3 cm lesion excision.

Bad news: This is a common documentation problem and unfortunately means the surgeon has given up some of his reimbursement. The lost revenue can be significant, especially for malignant lesions where a generous margin would be taken.