Lesion excision coding may seem complex, but reporting excision of benign (11400-11471) and malignant (11600-11646) skin lesions can be mastered in five steps.

Step 1: Measure First, Cut Second

When assigning CPT® codes 11400-11646, you must know both the size of the lesion(s) excised and the width of the margins (the area surrounding the lesion that is also removed). Per CPT® instructions, “Code selection is determined by measuring the greatest clinical diameter of the apparent lesion plus that [most narrow] margin required for complete excision.”

The provider should measure the lesion and margins prior to excision. This is because the lesion will “shrink” as soon as the incision releases the tension on the skin.

Step 2: Wait for the Pathology Report

CPT® codes for lesion excision (as well as ICD-10-CM diagnostic codes) require that you identify a lesion as either benign or malignant. For this reason, you should wait for the results of the pathology report before making a code selection. Only those lesions specifically identified as malignant may be assigned a code for malignancy.

Exception: If a surgeon performs a re-excision to obtain clear margins at a later operative session, you may report the same malignant diagnosis that you linked to the initial excision because the reason for the re-excision is malignancy.

Step 3: Location Matters

You need to know the anatomic location from which the lesion(s) is excised to determine proper coding. Multiple areas may be grouped together within a single set of codes: pay careful attention to code descriptors.

Step 4: Bundle Simple Repairs with Excision

Per CPT® guidelines, all lesion excision codes include simple wound closure. CPT® allows separate coding for intermediate (12031-12057) and complex (13100-13153) repairs; however, payers who follow National Correct Coding Initiative (NCCI) edits will bundle intermediate and complex repairs into excision of benign lesions of 0.5 cm or less (11400, 11420, and 11440).

Step 5: Report Each Lesion Separately

When the physician excises multiple lesions, code each lesion separately, assigning a specific CPT® and ICD-10-CM code for every lesion treated. When coding for multiple excisions, you should append modifier 59 Distinct procedural service to the second and all subsequent codes describing lesion excision in the same anatomic location.

To demonstrate our rules at work, let’s consider two examples:

Example 1: The surgeon excises a lesion from a patient’s right shoulder (location). Prior to excision, the lesion measures 1.5 centimeters at its widest; to ensure complete removal the surgeon allows a margin of at least 1.5 cm on all sides. Adding the largest diameter of the lesion (1.5 cm) to the narrowest margin (1.5 cm on each side, or 3.0 cm total) results in an excised diameter of 4.5 cm (size before excision). Subsequent to excision, the pathology report identifies the lesion as malignant. The correct code is 11606 Excision, malignant lesion including margins, trunk, arms or legs; excised diameter over 4 cm.

Example 2: The physician removes three lesions from the right arm. Pathology determines that two of these (with excised diameters of 1 cm and 1.5 cm) are benign. The third lesion (excised diameter 2.5 cm) returns malignant. First, report the excision of the malignant lesion (the “most extensive” procedure) using 11603 Excision, malignant lesion including margins, trunk, arms or legs; excised diameter 2.1 to 3.0 cm. Next, report the benign lesion excisions using 11402-59 Excision, benign lesion including margins, except skin tag (unless listed elsewhere), trunk, arms or legs; excised diameter 1.1 to 2.0 cm and 11401-59 Excision, benign lesion including margins, except skin tag (unless listed elsewhere), trunk, arms or legs; excised diameter 0.6 to 1.0 cm.