Internal Medicine Coding Alert

Question: When the internist performs benign lesion removal, should I calculate lesion size before or after the internist performs the procedure?

Oregon Subscriber

Answer: The internist should measure the size of the excision before performing the removal, and include it in the medical record. This benefits the practice, as the lesion will become smaller after the internist's first excision -- and will

shrink even further when placed in formaldehyde and shipped to the pathologist. According to CPT, calculate the excision size by "measuring the greatest clinical diameter of the apparent lesion plus the margin required for complete excision

(lesion diameter plus the most narrow margins required equals the excised diameter). The margins refer to the most narrow margin required to adequately excise the lesion, based on the physician's judgment. The measurement of lesion plus

margin is made prior to excision. The excised diameter is the same whether the surgical defect is repaired in a linear fashion or reconstructed."

Example: The internist removes a lesion from a patient's upper arm that measures 2.0 cm at its widest point. During the excision, he allows a margin of at least 0.2 cm. To calculate the excised diameter, you add the lesion size (2.0 cm) to the

width of the narrowest margin x 2 (0.4 cm) for a total of 2.4 cm. Choose an excision code based on a 2.4 cm removal -- in this case, either 11403 (Excision, benign lesion including margins, except skin tag [unless listed elsewhere], trunk,

arms,or legs [excised diameter 2.1 to 3.0 cm]) or 11603 (Excision, malignant lesion including margins, trunk, arms, or legs; excised diameter 2.1 to 3.0 cm), depending on pathology.