Skin lesion excision coding is one of the most calculation-intensive topics on the CPC exam. Every question requires you to correctly classify the lesion, measure it with margins, locate the right code range, and decide whether a separate repair code applies. Once you learn the systematic approach, these questions become some of the most predictable and manageable on the entire exam.
The Two Main Categories of Skin Lesion Excision
CPT divides skin lesion excisions into two categories based on the nature of the lesion:
- Benign lesions (11400–11471): Moles, cysts, lipomas, fibromas, and other non-cancerous growths
- Malignant lesions (11600–11646): Basal cell carcinoma, squamous cell carcinoma, melanoma, and other cancers
Within each category, codes are further organized by anatomical location and excised diameter in centimeters. Malignant lesion codes generally reimburse at a higher rate than benign codes because the excision technique and margins required are more extensive.
The Most Important Rule — Measure With Margins
This is the rule that most beginners miss. When coding a lesion excision, you do not use the size of the lesion alone. You use the size of the lesion plus the margins taken around it.
The correct measurement formula is:
Why multiply the margin by 2? Because margins are taken on all sides of the lesion. A 0.5 cm margin around a circular lesion adds 0.5 cm on one side and 0.5 cm on the other — totaling 1.0 cm added to the lesion diameter.
Example Calculation
A physician excises a benign lesion on the back. The lesion measures 1.2 cm and 0.3 cm margins are taken.
- Lesion: 1.2 cm
- Margins: 0.3 cm × 2 = 0.6 cm
- Total excised diameter: 1.2 + 0.6 = 1.8 cm
- Location: Trunk (back)
- CPT code: 11402 (Excision benign lesion, trunk, 1.1–2.0 cm)
Benign Lesion Code Ranges by Location
| Location | Code Range |
|---|---|
| Trunk, arms, or legs | 11400–11406 |
| Scalp, neck, hands, feet, or genitalia | 11420–11426 |
| Face, ears, eyelids, nose, lips, or mucous membranes | 11440–11446 |
Malignant Lesion Code Ranges by Location
| Location | Code Range |
|---|---|
| Trunk, arms, or legs | 11600–11606 |
| Scalp, neck, hands, feet, or genitalia | 11620–11626 |
| Face, ears, eyelids, nose, lips, or mucous membranes | 11640–11646 |
When to Add a Repair Code
After a lesion excision, the wound must be closed. Whether you can bill a separate repair code depends on the complexity of the closure:
- Simple closure: Included in the excision code — do NOT report separately
- Intermediate or complex closure: Report separately using the appropriate wound repair code (12031–13160)
- Adjacent tissue transfer or flap: Report separately using codes from 14000–14350
Multiple Lesion Excisions
When multiple lesions are excised during the same encounter, each lesion is coded separately. Unlike wound repairs, lesion excision lengths are NOT added together. Each lesion gets its own CPT code based on its own excised diameter and location. Report additional lesions with modifier -59 if needed to bypass NCCI edits.