Dermatology medical billing is decided lesion by lesion: what was done to it, how large it measured with margins, where on the body it sat, and what the pathologist eventually called it. One visit can produce an E/M, three biopsies, a destruction series and an excision with a layered closure, each with its own unit rule and bundling edit. Coding from the superbill before the path report is back leaks revenue both ways.
Biopsies, destructions and the add-on unit rules
Skin biopsies are reported by technique. A tangential shave is 11102 for the first lesion and 11103 for each additional, a punch is 11104 and 11105, and an incisional biopsy is 11106 and 11107. When techniques are mixed, only the most complex primary code is reported and the remaining lesions go on add-ons, so two primary biopsy codes on one claim hit an edit however modified.
Destruction follows a different ladder. Actinic keratoses are 17000 for the first, 17003 for each of the second through fourteenth, and 17004 alone at fifteen or more. Warts are 17110 or 17111 by count, and malignant destruction uses 17260 to 17286 by site and size. The note must state count and diagnosis for each group, or the add-on units draw a unit-edit denial.
Excisions are sized by the specimen and coded by the pathologist
Excision codes are chosen by excised diameter, the lesion plus the narrowest margin on each side measured before the specimen leaves the room, and by body area. Benign excisions run 11400 through 11446 and malignant 11600 through 11646. Only the pathology result decides between the families, so we hold every excision claim until the report posts.
A repair is separately reportable only when it is intermediate, 12031 through 12057, or complex, 13100 through 13153; a simple closure is included in the excision. Repair length is summed across wounds in the same anatomic group and complexity class rather than listed per wound, so adding repairs one line at a time overstates the claim.
The diagnosis follows the same timing. Uncertain behavior, D48.5, is a pathologist's word and belongs on the claim only after the report uses it; before that the lesion is coded to the clinical finding. Once the histology is known, the claim carries the confirmed code with the exact site.
Mohs surgery and the surgeon-as-pathologist requirement
Mohs is 17311 for the first stage and 17312 for each additional stage on the head, neck, hands, feet and genitalia, with 17313 and 17314 for the trunk and extremities. The codes assume one physician acts as both surgeon and pathologist and reads the frozen sections personally. If a separate pathologist reads the slides, the case is not Mohs for billing purposes and is reported as an excision with pathology.
A biopsy on the same day as Mohs is separately payable only when there was no prior pathologic diagnosis and the note explains why the frozen-section result was needed first; it carries modifier 59. The reconstruction is reported on its own and holds much of the reimbursement, so we reconcile the closure code to the operative note.
Modifier 25 and the same-day visit, the most audited pattern in derm
A skin check that finds a suspicious lesion, biopsies it and adjusts the patient’s acne regimen is a legitimate E/M plus procedure, and modifier 25 on the visit says so. Payers audit it accordingly. Examining the lesion that was biopsied belongs to the procedure and cannot support the visit.
Our coders apply 25 only when the note shows a different problem, a medication change or a total-body examination with findings beyond the treated lesion; otherwise we bill the procedure alone. For distinct lesions treated by different methods, modifier 59 or the more specific XS marks the separate site, and the lesion map is what holds on appeal.
Phototherapy, patch testing and the biologic calendar
Medical dermatology has its own recurring lines. Narrowband UVB is 96910 and PUVA is 96912, one unit per session, and payers watch the diagnosis on every line because coverage is limited to psoriasis and a short list of other conditions. Patch testing under 95044 is billed per allergen applied, and the count has to match the panel in the chart.
Biologics for psoriasis and hidradenitis are the highest-value drug lines in the practice. Each carries a J code billed by unit with the NDC, an administration code and an authorization naming a product, a dose and an end date, which we keep on the injection calendar so a maintenance dose is never given on an expired approval.
Cosmetic versus medically necessary, settled before the patient leaves
Skin tag removal under 11200, seborrheic keratosis treatment, spider vein sclerotherapy and many cyst removals are cosmetic by default and covered only when the note documents irritation, bleeding, obstruction or suspicious change. Payers apply that rule at the claim edit, after the patient has left, and the practice writes off a fee it could have collected at the desk.
We build the cosmetic screen into scheduling and check-in. When a service is unlikely to be covered, Medicare patients sign an ABN and commercial patients sign a self-pay agreement showing the fee, and the claim carries the modifier reporting that the patient accepted responsibility.
How we take on dermatology billing
We begin with a free A/R review that sorts your aging the way dermatology bills: claims stuck on units, excisions waiting on pathology, Mohs reconstructions denied, biologics waiting on authorization and cosmetic write-offs that should have been patient balances. Our coders hold AAPC or AHIMA credentials, the BAA is executed before any record is shared, and we work inside the PM and EHR you already use.
The handoff is a parallel period of two to four weeks in which the outgoing biller and our team code the same encounters, and the differences become your written policy on modifier 25, lesion counts and repair bundling. After the initial term the contract runs month to month with a named account manager.
Codes and Modifiers We Watch in Dermatology
The codes that most often decide whether a dermatology claim pays.
| Code | What it is | What goes wrong |
|---|---|---|
| 11102 / 11103 | Tangential skin biopsy, first lesion / each additional lesion | Additional lesions belong on the add-on regardless of technique; two primary codes edit against each other. |
| 11104 / 11106 | Punch biopsy / incisional biopsy, first lesion | Only the most complex technique is the primary code; 11105 and 11107 carry the rest. |
| 17000 / 17003 / 17004 | Destruction of premalignant lesions, first / second through fourteenth / fifteen or more | 17004 is billed alone. Units above the documented count trigger the medically unlikely edit. |
| 11400–11446 / 11600–11646 | Excision of benign / malignant lesion, by excised diameter with margins and by site | The path result decides the family; claims filed before it posts are underpaid or corrected later. |
| 12031–12057 / 13100–13153 | Intermediate / complex repair, by anatomic group and summed length | Simple repair is bundled into the excision. Lengths are totaled per group, not billed per wound. |
| 17311 / 17312 | Mohs surgery, head, neck, hands, feet or genitalia, first / each additional stage | The same physician must act as surgeon and pathologist. A same-day biopsy needs modifier 59 and a reason. |
| 96910 / 96912 / 95044 | Phototherapy with UVB / PUVA, per session, and patch testing, per allergen | Phototherapy is one unit per session with the diagnosis on each line. Patch tests are billed per allergen applied, and payers cap the count. |
| Modifier 25 | Significant, separately identifiable E/M on the day of a procedure | Appended to most dermatology visits and audited for it; the note must show work beyond the lesion treated. |
| 88305 / Modifier 26 / TC | Surgical pathology level IV, professional / technical component | An in-house lab splits the read from the processing; billing the global code for one part is an overpayment. |
Common Dermatology Denials and How We Fix Them
- CO-97
A simple repair, a second biopsy primary code or a same-day E/M is denied as included in a procedure already paid on the claim.
FixIf truly bundled, write it off and correct the charge master. If the note supports separate work, resubmit with 25, 59 or XS and the documentation that proves it.
- CO-4
A procedure is denied as inconsistent with its modifier or missing a required one, usually a destruction and biopsy pair without XS or a visit without 25.
FixCheck the lesion map in the note, attach the modifier that describes the separation and send a corrected claim. The pairing is added to the pre-submission edit list.
- PR-96
The service is denied as non-covered cosmetic care and moved to patient responsibility, typically skin tags or seborrheic keratoses with no documented symptom.
FixWhere the note records irritation, bleeding or change, appeal with the symptom and matching diagnosis. Where it does not, bill the patient under the ABN or self-pay agreement.
- CO-197
A biologic for psoriasis or hidradenitis is denied because the authorization was missing, expired or covered a different dose or product than the one given.
FixRequest retro-authorization where the plan allows it and appeal with dosing history where it does not. Authorization dates and approved products are tracked against the injection calendar.
- CO-151
Units on 17003, 11103 or 11105 exceed what the payer considers plausible for one date of service and the line is denied.
FixConfirm the lesion count against the note and resubmit at the documented count; when the count is genuinely high, appeal with the note.
| Bundling and unit edits applied | NCCI procedure-to-procedure pairs and medically unlikely editsSource: CMS, National Correct Coding Initiative |
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Dermatology Billing: Common Questions
Because the excision code family depends on whether the pathologist calls the lesion benign or malignant, and the malignant codes reimburse at a higher level. Billing on the day of surgery means guessing and then filing a corrected claim; holding for the path report removes the guesswork.
The note has to show work separate from the procedure: a different problem addressed, a prescription started or changed, or a total-body skin examination with findings beyond the treated lesion. Evaluating the lesion that was biopsied is part of the biopsy.
Yes. The drug goes out under its J code with the NDC and units calculated from the dose, alongside the administration code. We track each patient’s authorization end date and approved product, and flag plans that require specialty pharmacy rather than buy-and-bill before the order is placed.
The code has to match what is known on that date. A lesion sent for biopsy with no result yet is coded to the clinical finding or as a neoplasm of unspecified behavior, not as uncertain behavior, which is reserved for a pathologist’s reading. Once the report posts we update the claim to the confirmed histology and site.
The change runs as a two-to-four-week parallel period in which both teams code the same encounters and we reconcile the differences with your providers. Schedules do not pause, we work inside your existing PM and EHR, and the free A/R review is completed before any agreement is signed.