Dermatology Coding Primer

Dermatology is one of the more complex specialties when it comes to coding and billing.  Coders must be familiar with benign and malignant masses along with actions such as shaving, destruction, and performing biopsies. In addition, they must identify simple, intermediate, and complex repairs, and deal with sizing terms such as length, depth, width, and circumference. And don’t forget knowing the difference between centimeters and millimeters. Dermatologists are very adept at providing their coders with the information they need to code correctly, but this may not be the case for all other providers. Coders who need to code dermatology-related procedures need to understand what each skin condition really is.


Perhaps one of the least understood topics in dermatology billing is the use of modifiers, particularly after CMS issued new alphabetical HCPCS modifiers in 2015 to replace the overused 59. If you’ve struggled with when to use modifiers with your E/M and dermatology procedure codes, this blog post is for you.


When should I use the “25” modifier?

CMS defines the “25” modifier like this: “A significant, separately identifiable evaluation and management [E/M] service by the same physician on the same day of the procedure or other service.” Sounds simple enough, but in practice, it’s easy to get wrong. First, “25” should only be used with E/M codes for established patients (not new patients) and never with procedure codes. Knowing when to add an E/M code to a dermatology procedure is where many inexperienced coders go astray. The best way to conceptualize the “25” modifier is to subtract a procedure from a visit, and see what documentation remains. Physicians often forget included in procedure codes are pertinent history, discussion of treatment options, performing the procedure, and followup care.


1700x, 1711x, and 1100x codes include most of the E/M code elements; therefore, it’s not appropriate to bill an E/M code with these procedures. However, there’s an exception to every rule, and that’s where the “25” modifier comes into play. Let’s say a patient you’ve been monitoring comes in with a new lesion on her back that you decide to biopsy. The 11000 code stands alone in this instance. However, if during the discussion of risks and benefits of the procedure, for example, the patient mentions that she also has an itchy rash developing under her left arm that you examine and treat, a separate E/M code with the “25” modifier would be appropriate. It’s always a good idea to evaluate the documentation carefully and pull out everything related to the procedure itself. If there is enough material left over to justify a separate office visit, then you can safely add it using the “25.”


When should I use the “59” modifier versus XE, XP, XS, and XU?

The “59” modifier is by far the most frequently used—and misused, which is probably why CMS issued the new X- modifiers, basically as a subset of “59.” The “59” modifier allows unbundling of codes so that distinct procedures can be billed and the claim can pass Medicare’s bundling edits. The “59” modifier is attached to CPT codes to indicate a procedure or service was distinct or separate from other services performed on the same day. For example, if a patient undergoes cryosurgery of 4 actinic keratoses and a shave biopsy of a mole, the biopsy CPT code 11100 would require a “59” modifier. If three procedures are performed in a single office visit, the “59” modifier would need to be applied to the second and third procedures listed. Due to perceived overuse of the “59” modifier, CMS developed four new modifiers which became effective as of January 1st, 2015.


Assume a patient comes in for cryosurgery on two lesions and during the visit, the doctor decides to do a biopsy of a separate lesion on a different part of the body. In this case, the “59” modifier would need to be appended to the biopsy code. Now let’s imagine that a patient comes in for shave excisions of AK lesions on two separate parts of the body. In this case, each successive 113x code would need the “XS” modifier to establish that each service was performed on a separate and distinct structure. CMS policy also states that X- modifiers should never be used with E/M codes; in addition, any time one of the X-modifiers applies, it should be used instead of the “59” modifier. Here’s a quick summary of the other X-modifiers:


  • XE—A distinct service in a separate encounter.
  • XP—A distinct service performed by a separate provider.
  • XS—A distinct service on a separate organ or structure.
  • XU—A service that is distinct because it is unusual or doesn’t typically overlap the main service.



Correctly applying modifiers in the dermatology specialty requires a deep understanding of all the components and documentation requirements in codes with global periods. Only then can you choose the correct modifiers where applicable and avoid triggering an audit. If you have questions about billing for your dermatology practice, contact EchoScribe for a free consultation.

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