Making a Mountain out of a “Mohs” Hill

Mohs Procedure Miscoding: How Incorrect Billing Leads to Denials and How to Fix the Problems

Mohs surgery, a specialized and precise method of removing skin cancer, is one of the most common dermatologic procedures performed in-office. However, incorrect billing of Mohs procedures is a frequent issue in dermatology practices, leading to denials and reduced reimbursement. Billing errors for Mohs surgery can account for significant revenue loss and administrative burden, especially when claims are denied or underpaid. According to industry data, up to 25% of Mohs surgery claims are denied due to incorrect CPT codes or inaccurate documentation. This article explores common billing mistakes in Mohs procedures, the consequences of these errors, and how to ensure correct coding to prevent denials.

Understanding Mohs Procedure and Correct Coding

Mohs micrographic surgery is a highly effective and precise technique used to treat certain types of skin cancer, especially basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). The procedure involves the layer-by-layer excision of cancerous tissue, followed by microscopic examination to ensure all cancerous cells are removed.

CPT codes for Mohs procedures are specific and must reflect the complexity of the surgery, the size of the excised area, and the number of stages involved. The proper code selection is crucial to ensure that the procedure is reimbursed appropriately. Below are the common CPT codes used for Mohs surgery:

• 17311 – Mohs micrographic surgery, face, ears, eyelids, nose, lips; excised diameter excision of 0.5 cm or less
  
  
• 17312 – Mohs micrographic surgery, face, ears, eyelids, nose, lips; excised diameter excision of 0.6 to 1.0 cm
  
  
• 17313 – Mohs micrographic surgery, face, ears, eyelids, nose, lips; excised diameter excision of 1.1 to 2.0 cm
  
  
• 17314 – Mohs micrographic surgery, face, ears, eyelids, nose, lips; excised diameter excision of 2.1 to 3.0 cm
  
  
• 17315 – Mohs micrographic surgery, face, ears, eyelids, nose, lips; excised diameter excision of 3.1 to 4.0 cm
  
  
• 17316 – Mohs micrographic surgery, face, ears, eyelids, nose, lips; excised diameter excision of 4.1 cm or greater
  
  
• 17317 – Mohs micrographic surgery, other than face, ears, eyelids, nose, lips; excised diameter excision of 0.5 cm or less
  
  
• 17318 – Mohs micrographic surgery, other than face, ears, eyelids, nose, lips; excised diameter excision of 0.6 to 1.0 cm
  
  

What Can Go Wrong: Common Billing Mistakes

Incorrect billing of Mohs procedures occurs when practices make errors in selecting the wrong CPT codes, improper documentation, or failure to follow payer guidelines. Here are some common mistakes:

1. Incorrect CPT Code Selection

• Mistake: The most common error is selecting an incorrect CPT code based on the size of the excised lesion or the location of the procedure. For example, billing a code meant for smaller excisions when the excision was larger, or using the wrong code for facial lesions versus non-facial lesions.
  
  
• Impact: Incorrect code selection leads to underpayment or denial. Insurers may argue that the excision was improperly reported, resulting in the claim being rejected.
  
  

2. Not Documenting the Number of Stages

• Mistake: Failing to document the number of Mohs stages required to completely remove the cancerous tissue.
  
  
• Impact: Mohs surgery is often performed in multiple stages, and each stage should be documented accurately. If the number of stages is not clearly stated, the payer may deny the claim or reimburse incorrectly. The stages impact the final CPT code selection.
  
  

3. Failure to Properly Document the Size of the Excision

• Mistake: Not accurately measuring the size of the excised lesion, which is essential in selecting the correct CPT code.
  
  
• Impact: Incorrectly measuring or documenting the size of the excision can lead to denials or underpayments. This is particularly crucial when the excised diameter is near the boundary between two code categories (e.g., 0.5 cm or 0.6 cm).
  
  

4. Underreporting the Complexity of the Procedure

• Mistake: Coding for a simple Mohs procedure when the excision is complex, such as multiple stages or extensive tissue removal.
  
  
• Impact: Underreporting the complexity leads to underpayment, as the procedure was more involved than initially documented. Complex cases require more stages, and failure to document this can lead to denials.
  
  

5. Incorrect Use of Modifiers

• Mistake: Not using the appropriate modifiers for situations like bilateral procedures, or when a significant, separately identifiable service was provided during the same visit.
  
  
• Impact: The absence of the proper modifier (e.g., modifier 59) can result in denials or reduced payments for services that should be reimbursed separately.
  
  

6. Inconsistent Reporting of the Lesion’s Location

• Mistake: Not accurately reporting the location of the excised lesion, especially when it is on highly reimbursed areas like the face, ears, eyelids, nose, or lips.
  
  
• Impact: Mohs procedures performed on the face typically receive higher reimbursement rates than those on other body areas. Failure to document the lesion’s location accurately can lead to underpayments or misreimbursement.
  
  

The Financial Impact of Mis-Coding

According to a 2023 survey by the American Academy of Dermatology, approximately 25% of Mohs surgery claims are denied due to incorrect coding or incomplete documentation. This can significantly impact the financial health of a dermatology practice, especially in high-volume settings. Practices may face revenue loss, increased administrative costs for resubmissions and appeals, and delays in receiving payments.

How to Fix the Problem: Best Practices for Correct Coding

1. Accurate Documentation of Lesion Size and Location

• Always measure and document the size of the excised lesion accurately in the patient’s medical records. Include details about the location, particularly if the lesion is on the face, ears, eyelids, nose, or lips, as these areas require specific codes.
  
  

2. Report the Number of Stages Performed

• Clearly document the number of stages required for the excision, as this directly impacts the billing process. Ensure that the number of stages aligns with the complexity of the procedure.
  
  

3. Use the Correct CPT Codes Based on Size and Location

• Select the correct CPT code based on the excised diameter and the location (e.g., facial vs non-facial). Double-check the code for both excision size and location to ensure they match the documentation.
  
  

4. Apply the Appropriate Modifiers

• Use modifiers like modifier 59 to indicate that multiple distinct procedures were performed during the same session. Ensure that all applicable modifiers are properly used to avoid denials.
  
  

5. Regular Training and Audits

• Implement regular training sessions for coders and clinical staff to keep them updated on CPT coding guidelines and payer-specific requirements. Internal audits of Mohs claims can also help identify coding errors before claims are submitted.
  
  

6. Pre-Billing Review

• Conduct pre-billing reviews of the medical documentation to ensure all necessary information is present, including lesion size, location, number of stages, and complexity of the procedure. This can reduce errors before claims are submitted to insurers.
  
  

Conclusion: Avoiding Mohs Procedure Mis-Coding

Correct coding for Mohs procedures is crucial to ensure appropriate reimbursement and avoid the financial and administrative burden of denials. By focusing on accurate documentation, selecting the correct CPT codes, and using the appropriate modifiers, dermatology practices can significantly reduce the likelihood of denied claims and underpayment. Regular training, audits, and pre-billing reviews can help ensure that the Mohs surgery process is correctly coded, leading to timely and accurate reimbursements for the practice.

With proper documentation and correct coding, dermatology practices can maximize their revenue and continue providing high-quality care for their patients. Call us today to see how we can help decrease the ever growing mountain of unresolved AR; let’s start with one Mohs at a time!