Measuring a lesion and choosing the appropriate excision code

By Faith C. M. McNicholas, RHIT, CPC, CPCD, PCS, CDC, Manager, Lead Coding and Reimbursement Strategist, June 1, 2024

Academy coding staff address important coding topics each month in DermWorld Coding Consult. Read more Derm Coding Consult articles.

Benign and malignant lesions present significant challenges in clinical practice, necessitating precise treatment strategies for optimal outcomes. While dermatology offers a range of therapeutic options, excision emerges as the cornerstone treatment approach for both types of lesions due to its efficacy in achieving complete removal, accurate histopathological diagnosis, and low recurrence rates.

Once a decision is made by the dermatologist or non-physician clinician (NPC) to excise a lesion based on the lesion characteristics and location, adherence to specific coding and documentation protocols is essential for accurate coding and claim reporting. This article aims to elucidate the requirements for lesion measurement and documentation, facilitating precise code selection in clinical practice.

1. Documentation requirements

When reporting excision codes, precision is key. It is important to select the most specific code that accurately reflects the procedure performed, taking into account the lesion’s characteristics and morphology. This ensures accurate reimbursement and reduces the likelihood of claim denials or audits. Accurate and comprehensive medical record documentation is paramount for determining the appropriate code(s) that can be reported.

In dermatology, this entails providing a detailed description of the skin lesion(s), including the location, size, and specific lesion characteristics that deem the lesion medically necessary to be treated. Additionally, documenting the method or technique employed for treating the lesion and noting any potential complications is crucial.

To justify the medical necessity of lesion excision, it is essential to include descriptive terms such as “suspicious lesion,” “changing mole,” “history of bleeding lesion,” “variable pigmentation,” or “atypical-appearing nevus.” Such descriptions indicate a therapeutic intent and support the need for intervention.

Before determining the treatment technique, the dermatologist/NPC must first determine the morphology of the lesion which can be achieved either through a skin biopsy with subsequent histopathological examination or visual assessment by the dermatologist/NPC based on specific lesion characteristics such as size, shape, color, texture, and the patient’s medical history. Photographs can also serve as valuable documentation aids.

When reporting excision procedures, it is important to select the most precise code that accurately reflects the procedure performed including the technique utilized as well as the lesion characteristics and morphology. This meticulous approach not only ensures accurate reimbursement but also mitigates the risk of claim denials or audits.

It bears repeating that skin biopsy with histopathology is the gold standard for differential diagnosis.

─ NIH National Library of Medicine

In instances where the dermatologist/NPC is uncertain about the clinical morphology of the lesion excised, it is advisable to withhold claim submission until the pathology report is available for reference. Reporting the diagnosis and procedure technique based on the pathology findings allows for accurate coding and reporting of services rendered. Moreover, it helps prevent upcoding based on erroneous clinical diagnoses, thereby maintaining integrity and compliance within the coding process.

2. Determine the treatment technique

Excision is defined as full-thickness (through the dermis) removal of a lesion, including margins, and includes simple (nonlayered) closure when performed. Each excised lesion (benign or malignant) is reported separately.

In some cases, the closure of defects created by an excision may require intermediate (layered) or complex closure. These closure methods, if performed, should be documented, and reported separately.

3. Determine the lesion size

Lesions vary in size, shape, and depth, and precise measurement is critical for diagnosis and treatment planning. Measuring of lesions should be made prior to skin excision because the skin’s elasticity usually causes the excised area to expand to a larger defect after the incisions are made. When coding the removal of a lesion, do not report the size of the surgical defect created or the affected area.

Lesions are typically measured in three dimensions: length, width, and depth. In the context of Current Procedural Terminology (CPT) coding, “excised diameter” refers to the measurement of the lesion that has been surgically removed. It typically refers to the length (longest dimension) and width (perpendicular measurement to the length) of the lesion, measured at its widest points. “Margins” refer to the surrounding tissue that is also removed along with the lesion to ensure complete excision and to minimize the risk of recurrence. The depth of the excision is also required to determine how deep the lesion extends into the skin or tissue. The latter confirms whether a full-thickness excision has been performed and not a shave removal (transverse incision or horizontal slicing to remove epidermal and dermal lesion without full-thickness excision).

The length of the ellipse is not included when determining the size of the lesion and the margins needed to excise the lesion.

If the lesion is asymmetrical or irregular, the maximum width is used to measure the lesion. The dermatologist/NPC should make an accurate measurement of the lesion at the time of the excision, and the size of the lesion should be documented in the medical record. Do not rely on obtaining the measurement from the pathology report as it is less likely to contain an accurate measurement due to the shrinkage or fragmentation of the specimen.

The CPT code descriptor to be reported for the skin lesion excision includes the lesion size plus the required margins for the “excised diameter” that allows for complete lesion excision, allowing for a description that can be consistently applied. Therefore, the lesion size plus the excised margins must be documented to indicate the total excised lesion size.

The margins of the excision (i.e., the amount of normal tissue removed along with the lesion) will impact code selection. Codes for excisions with narrow margins may differ from those with wider margins.

4. Determine how much tissue will be removed to achieve complete abnormal tissue excision

Benign lesions typically require excision of a smaller margin of grossly normal skin to achieve complete excision of the lesion. Like the excision of benign lesions, an ambiguous but low-suspicion lesion might be excised with minimal surrounding, grossly normal skin, or soft tissue margins. Pathology will generally confirm a benign lesion and the service is appropriately reported using the excision of benign lesion CPT codes 11400 - 11471.

An ambiguous but moderate-to-high suspicious lesion would be excised with moderate-to-wide surrounding, grossly normal skin, or soft tissue margins and would be reported with the appropriate CPT code based on the histopathological findings depicting the lesion morphology.

On the other hand, excision of malignant lesions will require variably larger margins and is appropriately reported with excision of malignant lesion CPT codes 11600-11646.

The AMA CPT coding manual often provides illustrations and guidelines to help dermatologists/NPCs accurately determine the total excised diameter of a lesion. These illustrations, also reproduced in the AAD Coding and Billing Manual, depict how to measure the lesion, and determine its dimensions, aiding in the selection of the appropriate CPT code for the procedure performed.

For instance, if a benign lesion on the neck measures 1.0 cm by 2.0 cm, the excised diameter would be 2.0 cm (the longest dimension). An additional 0.2 cm margin on each side (0.4 cm) is excised to ensure complete excision of the lesion resulting in a total excised lesion size of 2.4 cm.

Based on this information, the appropriate CPT code for the excision of this lesion (2.4 cm) is 11423, which corresponds to excision, benign lesion including margins, except skin tag (unless listed elsewhere), scalp, neck, hands, feet, genitalia; excised diameter 2.1 to 3.0 cm.

Excision of benign lesion of the neck

Source: AMA CPT Coding Manual

Similarly, a malignant lesion excision on the nose measuring 0.9 cm with an additional 0.3 cm margin on each side results in an excised diameter of 1.5 cm (lesion plus margins: 0.9 cm + 0.6 cm) = 1.5 cm and is appropriately reported with CPT code 11642 excision, malignant lesion including margins, face, ears, eyelids, nose, lips; excised diameter 1.1 to 2.0 cm.

Excision, malignant lesion of the nose

Source: AMA CPT Coding Manual

5. Determine the appropriate procedure code

Once the technique for treatment is determined, and the lesion has been measured accurately to determine the lesion size, the dermatologist/NPC can perform the excision and document the procedure. The documentation is used to justify the determination of the appropriate procedure code that represents the morphology, location, and lesion size excised.

Each benign lesion excised should be reported separately. Code selection is determined by measuring the greatest clinical diameter of the apparent lesion plus that margin required for complete excision (lesion diameter plus the narrowest margins required equals the excised diameter).

The CPT code set categorizes excision codes based on the location, size, and morphology of the lesion and includes simple closure. If an intermediate or complex closure is performed, it must be reported as a separate procedure. For excision of benign or malignant lesions requiring intermediate or complex closure, report 11400-11446 in addition to appropriate intermediate (12031-12057) or complex closure (13100-13153) codes.

When reporting excision codes, it is important to use the most specific code that accurately reflects the procedure performed based on the characteristics of the lesion. This includes accurately measuring and documenting the lesion size, and choosing the appropriate excision code, both aspects that are essential to correct coding and billing. This ensures proper reimbursement and reduces the risk of claim denials or audits.

Accurate documentation is crucial for coding excision procedures correctly. Dermatologists/NPCs should include detailed descriptions of the lesion, including its location, size (length, width, depth), margins, and any additional information supportive of a successful surgical encounter that can include:

• Type and volume of anesthesia, if performed

• Type of hemostatic techniques used (chemical, electrodesiccation, electrocautery, etc.)

• Estimated blood loss

• Type of closure

• Follow-up instructions

• Surgical complications (presence or absence of)

Photographs may also be useful for documentation purposes.

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