What You Need to Know to Code Excisions
From anatomy to math, coding lesion excisions requires you to be a quick study.
Coding surgical excisions of the skin requires the medical coder to have basic knowledge of skin anatomy, the different types of lesions, and the various approaches surgeons use to excise lesions. Be sure you have all the facts before attempting to code these claims.
Skin Anatomy 101
When coding for surgical excision of the skin, keep in mind the landmarks that define the depth of the excision. The three main layers of the skin are the epidermis, dermis, and hypodermis or subcutaneous layer. The epidermis varies from .05 mm to 1.5 mm in thickness, the dermis ranges from 1.5 mm to 4 mm, and the thickness of the hypodermis is unique to each person. Superficial fascia marks the boundary between the skin and deeper tissue.
Types of Lesions
Benign lesions are non-cancerous growths that do not spread to distant sites in the body. Here is a short list of different types of benign lesions:
- Benign neoplasm
- Cicatricial (scar tissue)
- Cutaneous mastocytosis
- Dermoid cyst
- Fibrous (dermatofibroma)
- Melanocytic nevi
- Sebaceous cyst
- Skin nevus
Malignant lesions behave differently; they can spread to sites beyond the skin by a process called metastasis, or “mets,” for short. Cancer is always named for the place it starts — for example, metastatic skin cancer is still skin cancer. Here is a short list of different types of malignant lesions:
- Malignant melanoma
- Merkel cell carcinoma
- Basal cell carcinoma
- Squamous cell carcinoma
- Melanoma in situ
- Carcinoma in situ
There is a third classification that is more difficult to code: lesion with uncertain histologic behavior, as discussed by Barbara J. Cobuzzi, MBA, CPC, COC, CENTC, CPC-P, CPC-I, CPCO, CMCS, in her article “Coding Uncertain Lesion Excisions With Certainty.”
Size Matters When Coding Excisions
Code selection is driven by the histology of lesion and the method of removal, so documentation must support what is being removed, as well as how it is being removed. Lesions can be destroyed by laser, chemically, or by curette (razor blade) or scalpel. The final determinants are location and size. Both benign and malignant codes include the same groups of anatomic locations, with one exception: Benign includes the mucous membrane.
The size of the lesion at its greatest clinical diameter plus the planned margins at their narrowest equals the excised diameter. The lesion and two planned narrowest margins must be measured prior to the procedure. (If margins aren’t included, CPT® guidelines instruct to code the widest diameter.) There are six excised diameters listed in centimeters for each group of anatomic locations: 0.5 or less, 0.6 to 1.0, 1.1 to 2.0, 2.1 to 3.0, and 3.1 to 4.0. You may see millimeters documented; there are 10 millimeters to each centimeter. Watch out for decimals: 0.5 cm is half a centimeter or 5 millimeters.
Example documentation for 11604 Excision, malignant lesion including margins, trunk, arms, or legs; excised diameter 3.1 to 4.0 cm:
Patient presents for excision of biopsy proven squamous cell carcinoma on the right arm. The lesion measures 2.5 cm x 2 cm. The lesion and surrounding area were prepped in the usual sterile manner and 1% lidocaine infiltrated. Using a scalpel, an elliptical incision with margins of 6 mm and 1.5 cm was carried down to the dermal layer. The lesion and surrounding margins were removed. The skin edges were reapproximated and repaired in a single layer with 2-0 Prolene. The resulting repair measured 5.5 cm. Antibiotic creme and sterile dressing were applied.
Code for each lesion. Local anesthesia and simple repair are included in both benign and malignant lesion excisions. You can bill separately for intermediate and complex repairs for most excisions. See Jennifer McNamara’s article “Close the Gap in Wound Repair” on page 20 for details. Do not confuse shave removal of a lesion with excision of a lesion. Shave removal is reported using CPT® codes 11300-11313 — these codes do not describe a shave biopsy.
Benign neoplasm of skin (Concept Id: C0004998) – MedGen – NCBI.
AMA CPT® Assistant April 2010.