General Surgery Coding Alert

Question: In an op report for a malignant lesion excision from the patient’s forearm, the surgeon documented an elliptical excision that was 8.3 cm long but only 1.6 cm wide for a 1.2 cm lesion. With so many measurements, I don’t know how to decide the “excised diameter” so I can choose the correct code. Please help.

Georgia Subscriber

Answer: The rules for coding malignant lesion excision indicate that you should calculate the excised diameter as the narrowest margin times two.

Because the surgeon documents an elliptical incision, you should forget the incision length, which is longest dimension (8.3 cm), when calculating the excision size. Instead, you need to use the incision width, which is the shortest dimension (1.6 cm) as the excised diameter. That leads you to code 11602 (Excision, malignant lesion including margins, trunk, arms, or legs; excised diameter 1.1 to 2.0 cm).

Heads up: The op report you describe gives you the excision dimensions, but more commonly, the op report will state the lesion diameter and the margin dimension. For instance, in this case the surgeon might describe a 1.2 cm diameter lesion and state that he used 0.2 cm margins. Remember that margins are on all sides of the lesion, so you must count them twice when calculating the excision diameter. In this case, that’s a 1.2 cm lesion plus two times 0.2 cm margin for a lesion excision of 1.6 cm. If the surgeon uses an elliptical incision and claims a 0.2 cm margin, that will refer to the narrowest margin. You won’t necessarily know the margin in the longer dimension, but then, you don’t need to know that to select the correct code.