Dermatology sits in a spot that most medical specialties do not. A large portion of what happens in a derm practice is medically necessary, covered by insurance, and billable to payers. But right next to that is a full menu of cosmetic services that are never covered and must be billed directly to the patient. The line between the two is not always as clean as it sounds, and that is exactly where most billing problems start.
When cosmetic and medical services overlap in the same visit, the same procedure, or even the same diagnosis, coding errors happen. Those errors lead to denied claims, refund demands, and in serious cases, compliance investigations. Let us look at where practices get tripped up the most.
The Same Procedure, Two Different Reasons
Here is a situation that plays out in derm offices every day. A patient comes in with a lesion. The provider evaluates it and determines it should be removed. If that removal is done because the lesion is suspicious for malignancy or causing symptoms like pain or irritation, it is a medical procedure. The insurance company covers it. If that same removal is done because the patient does not like the way it looks, it is cosmetic. The patient pays out of pocket.
The CPT code for the removal might be identical in both scenarios. What changes is the diagnosis code. A medical removal will carry an ICD-10 code that supports the clinical necessity, something like a neoplasm code, a code for a symptomatic skin condition, or a code for a lesion in a location that causes functional impairment. A cosmetic removal might only have a diagnosis code related to appearance or patient preference.
The mistake practices make is assigning a medical diagnosis to a cosmetic procedure to get it covered by insurance. This is not just a coding error. It is a false claim. And payers audit for it regularly, especially in dermatology where the overlap is well known.
Mohs Surgery & the Documentation Burden
Mohs micrographic surgery is one of the highest-reimbursing procedures in dermatology, and it gets heavy scrutiny from payers. The coding for Mohs involves the number of stages, the number of tissue blocks examined per stage, and the repair or reconstruction that follows.
The most common billing issue with Mohs is documentation that does not clearly support the number of stages billed. Each stage must have its own operative documentation, including the tissue mapping and pathology findings. If a practice bills for three stages but the note only details two, the third stage will be denied, and the payer may audit the practice’s entire Mohs claim history.
On the cosmetic side, some practices perform Mohs on lesions that could have been treated with simpler methods, and the payer questions medical necessity. When the pathology does not support the use of Mohs over a standard excision, the reimbursement is at risk.
Cosmetic Consults That Turn Medical
A patient books a cosmetic consultation for Botox or filler. During the visit, the provider notices an irregular mole and decides to biopsy it. Now the visit has both a cosmetic component and a medical one. How do you bill that?
The answer is to split the visit. The cosmetic consult is billed to the patient. The medical evaluation and biopsy are billed to the insurance carrier with appropriate E/M and procedure codes, along with supporting diagnosis codes. Modifier 25 may be needed on the E/M if a procedure is performed on the same day.
Where practices get into trouble is billing the entire visit to insurance, including the cosmetic portion, or failing to bill the medical portion at all because the visit was originally scheduled as cosmetic. Both scenarios lose money. One risks a compliance issue, the other leaves legitimate revenue uncollected.
Destruction Codes & the Counting Problem
Destruction of benign and premalignant lesions is bread-and-butter dermatology billing. CPT codes 17000 through 17004 cover destruction of premalignant lesions like actinic keratoses. Code 17000 is for the first lesion, and 17003 covers each additional lesion after the first, grouped in units.
The billing mistake here is in the counting. If a provider destroys 12 actinic keratoses, the claim should include 17000 for the first and 17003 with 11 units for the rest. Some practices bill 17000 twelve times, which results in denials or reprocessing. Others undercount because the operative note is vague about the number of lesions treated.
For cosmetic destruction, such as removal of skin tags for appearance, none of these codes should be submitted to insurance. The patient is responsible for the full cost. Mixing cosmetic and medical lesion counts on the same claim creates confusion and audit exposure.
Global Period Billing Errors
Many dermatologic surgical procedures carry a 10-day or 0-day global period. During the global period, follow-up visits related to the procedure are included in the surgical fee. Billing a separate E/M during the global period for routine post-operative care results in a denial, and repeated violations get flagged.
The exception is when the follow-up visit involves a new or unrelated problem. In that case, modifier 24 is appended to the E/M code. But again, the documentation must support that the visit addressed something separate from the surgical recovery. Templated notes that look the same as every other post-op visit will not hold up under payer review.
Getting the Split Right
Dermatology billing comes down to one discipline: knowing where the line is between medical and cosmetic, and documenting on the correct side of it. Every procedure, every visit, and every diagnosis code should clearly reflect the clinical reason for the service. When a visit includes both cosmetic and medical components, the billing must split them accurately.
Practices that invest in staff training on cosmetic versus medical coding, maintain clean documentation standards, and audit their claims regularly avoid the most costly mistakes. The revenue is there. It just has to be coded correctly and supported by the chart.