Dermatology Billing Guide: Codes & Modifiers
Dermatology coding turns on distinctions that look small in the chart and are decisive on the claim: what technique removed the tissue, how many lesions were treated, whether the lesion was benign or malignant, and how the specimen was measured before it went in formalin.
This is a code reference for the procedures a dermatology practice bills most: biopsies, destructions, excisions, Mohs micrographic surgery, and dermatopathology — plus the modifier set that keeps them from bundling into each other.
Quick Answers
- Biopsy codes are technique-based: tangential, punch, and incisional each have their own primary and add-on code.
- Destruction codes are count-based for premalignant and benign lesions, and size/site-based for malignant ones.
- Excision codes are measured before excision — lesion diameter plus the narrowest margins on each side, not the size of the specimen in the jar.
- Mohs is surgeon and pathologist in one. The same physician performs both roles, which is why separate surgical pathology on the same lesion is not separately reportable.
- Modifier 25 and modifier 59 carry most of the risk in a dermatology claim, and both are assertions the documentation has to back up.
Skin Biopsy Codes
Biopsy coding is selected by the technique the physician used, not by the body site and not by what the pathologist later found. Each technique has a primary code for the first lesion and an add-on code for each additional lesion in the same session.
| Technique | First lesion | Each additional | What defines it |
|---|---|---|---|
| Tangential (shave, scoop, saucerize, curette) | 11102 | 11103 | Sharp blade removes a sample of epidermis and a portion of dermis |
| Punch | 11104 | 11105 | Punch tool removes a full-thickness cylindrical sample; includes simple closure |
| Incisional | 11106 | 11107 | Scalpel removes a full-thickness sample, often into subcutaneous fat |
When multiple techniques are used in one session
Report the single highest-level technique as the primary code, once, and every remaining biopsy — regardless of technique — as add-on units. The hierarchy runs incisional, then punch, then tangential. A punch biopsy of one lesion and two shave biopsies of others is one 11104 plus two units of 11103, not three separate primaries.
When a biopsy is not separately reportable
A biopsy is included in a more extensive procedure performed on the same lesion at the same session. If the lesion is excised or destroyed, the sampling that happened on the way there is part of that service. The biopsy becomes separately reportable only when it is performed on a different lesion, or when it is a diagnostic biopsy whose result determines whether and how to treat — and in that case the documentation and an appropriate modifier have to make the separateness explicit.
Destruction Codes
Destruction covers ablation by any method — cryosurgery, electrosurgery, laser, chemical. The code family depends on what the lesion was, and within a family the code depends on how many lesions were treated.
| Lesion type | Codes | How the count works |
|---|---|---|
| Premalignant (e.g., actinic keratoses) | 17000, 17003, 17004 | 17000 for the first lesion, 17003 per lesion for the second through fourteenth, 17004 instead of the others when fifteen or more are treated |
| Benign (other than skin tags or cutaneous vascular lesions) | 17110, 17111 | 17110 covers up to fourteen lesions as a single unit; 17111 covers fifteen or more |
| Malignant | 17260–17286 | Selected by anatomic site and by lesion diameter; each lesion is reported separately |
The premalignant and benign families count differently, which is the single most common destruction error. 17003 is reported per lesion as an add-on; 17110 is reported once for the whole group of up to fourteen. Billing 17110 with fourteen units instead of one unit is an overpayment waiting to be recovered.
Excision Codes and Repairs
Excision codes are chosen by three things: whether the lesion is benign or malignant, the anatomic site, and the excised diameter.
| Lesion | Range | Selected by |
|---|---|---|
| Benign | 11400–11446 | Site family, then excised diameter |
| Malignant | 11600–11646 | Site family, then excised diameter |
Measure before you cut. The excised diameter is the clinical lesion diameter at its widest point plus the narrowest margin taken on each side. It is recorded in the operative note before excision, in centimeters. A specimen measured after removal has already shrunk, and a chart that only records the post-excision specimen size cannot support the code that was billed.
Which repairs are separately reportable
Simple closure is included in the excision code. Intermediate repair (12031–12057, layered closure) and complex repair (13100–13153) are separately reportable when the documentation describes what made the closure more than simple — layered closure of deeper tissue, extensive undermining, debridement of traumatized tissue, or a scar revision. Adjacent tissue transfer codes (14000–14302) include the lesion excision itself, so the excision is not reported again alongside them.
Mohs Micrographic Surgery
Mohs is coded differently from every other dermatologic procedure because of a single fact: the surgeon and the pathologist are the same physician. The codes already contain the excision, the mapping and color-coding, the frozen sectioning, and the microscopic examination.
| Code | Anatomic area | What it reports |
|---|---|---|
| 17311 | Head, neck, hands, feet, genitalia, and specified other sites | First stage, up to five tissue blocks |
| 17312 | Same sites | Each additional stage, up to five tissue blocks |
| 17313 | Trunk, arms, legs | First stage, up to five tissue blocks |
| 17314 | Trunk, arms, legs | Each additional stage, up to five tissue blocks |
| 17315 | Any site | Each additional block beyond the first five, in any stage |
Rules that decide most Mohs denials
- Do not report surgical pathology separately for the Mohs specimens. The microscopic examination is inside the Mohs code. Billing 88302–88309 for the same tissue is duplicate billing.
- Stages, not lesions, drive the units. Each additional stage on the same lesion is 17312 or 17314; a second lesion at a different site starts over at a first-stage code.
- Blocks are counted per stage. 17315 applies only to blocks beyond five within a stage, and it can be reported for more than one stage in the same session.
- A same-day biopsy is separately reportable only when the diagnosis was not already established. If the patient arrives with a known, biopsy-proven malignancy, there is nothing left to diagnose. When the diagnosis genuinely is established that day, the biopsy and its pathology are reported with an appropriate modifier and the note has to say the decision to perform Mohs followed the result.
- Repair is separate. Closure of the Mohs defect — including flaps and grafts — is reported in addition to the Mohs codes when performed.
Dermatopathology Codes
When the specimen goes to a pathologist rather than being read in the Mohs suite, the pathology side has its own codes — and its own professional/technical split.
| Code | What it covers |
|---|---|
| 88304 | Surgical pathology, gross and microscopic, Level III |
| 88305 | Surgical pathology, gross and microscopic, Level IV — the level most skin biopsies fall into |
| 88312 | Special stain for microorganisms |
| 88313 | Special stain, Group II (other than microorganisms) |
| 88341, 88342 | Immunohistochemistry, per specimen and per additional antibody |
Two structural points matter for a dermatology practice. First, the unit is the specimen — each separately identified and separately submitted lesion is its own unit, which is why specimen labeling in the procedure room determines the pathology claim. Second, pathology codes split into professional and technical components the same way imaging does: a practice that owns the lab and employs the dermatopathologist bills globally, while a practice that sends slides out bills only the component it actually performed.
Dermatology Modifier Reference
| Modifier | Use it when | What it is asserting |
|---|---|---|
| 25 | A significant, separately identifiable E/M was performed on the same day as a procedure | That the visit addressed something beyond the decision to do the procedure, and the note documents it separately |
| 59 / XS | Unbundling a code pair when the services were at a separate site or session | That the NCCI edit does not apply because the lesions or sessions were genuinely distinct |
| 51 | Multiple procedures in one session, for payers that want it | Nothing clinical — it is a payment-sequencing modifier, and many payers append it themselves |
| 58 | A staged or planned related procedure during the global period | That the return was anticipated, not a complication |
| 78 | An unplanned return to the operating room for a related problem | That the return was a complication of the original procedure |
| 79 | An unrelated procedure during the global period | That this is different work on a different problem |
| LT / RT | Identifying laterality for paired sites | Which side, for payers that track it |
| GA, GX, GY, GZ | Services the payer may not cover | Whether an ABN was obtained, and whether the service is statutorily excluded |
Modifier 25 is the one most likely to be reviewed. An E/M on the same day as a lesion destruction is reportable only when the visit did work beyond the procedure itself — evaluating a separate complaint, or making a new diagnosis that led to the decision to treat. A note that documents only the lesion and the procedure does not support it.
Cosmetic vs. Medically Necessary
The coding question and the coverage question are separate. A benign lesion removal is a legitimate CPT code whether or not the payer covers it; what changes is the modifier set and the financial responsibility path.
The documentation that supports medical necessity for a lesion removal describes the symptom, not the appearance: bleeding, itching, pain, rapid change, obstruction of vision or function, or a clinical suspicion of malignancy. "Patient requested removal" does not support coverage, and an ABN plus a GA modifier is the correct handling for that case rather than a stronger diagnosis code.
The operational side of this — disputing cosmetic denials, appealing medical-necessity determinations, and building the documentation templates that prevent them — is covered on our dermatology billing services page.
Frequently Asked Questions
Which CPT codes are used for a skin biopsy?
Biopsy codes are technique-based. Tangential biopsy is 11102 for the first lesion and 11103 for each additional; punch biopsy is 11104 and 11105; incisional biopsy is 11106 and 11107. When multiple techniques are used in one session, report the highest-level technique once as the primary code and everything else as add-on units.
How do I code destruction of actinic keratoses?
Report 17000 for the first premalignant lesion destroyed and 17003 for each additional lesion from the second through the fourteenth. When fifteen or more lesions are destroyed, report 17004 alone instead of 17000 and 17003.
Can surgical pathology be billed with Mohs surgery?
No. The Mohs codes 17311 through 17315 already include the mapping, frozen sectioning, and microscopic examination performed by the same physician acting as both surgeon and pathologist. Reporting 88302 through 88309 for those same specimens is duplicate billing. Repair of the surgical defect, however, is reported separately.
How is lesion size measured for excision coding?
Measure before excising. The excised diameter is the widest clinical diameter of the lesion plus the narrowest margin taken on each side, recorded in centimeters in the operative note. A specimen measured after removal has shrunk and will not support the code billed.
When does modifier 25 apply in dermatology?
Modifier 25 applies when a significant, separately identifiable evaluation and management service was performed on the same day as a procedure — for example, evaluating an unrelated complaint, or making the new diagnosis that led to the decision to treat. A note that documents only the lesion and the procedure performed does not support it.
Is 17110 billed once or per lesion?
Once. 17110 covers the destruction of up to fourteen benign lesions as a single unit; 17111 covers fifteen or more. This is different from the premalignant family, where 17003 is reported per lesion. Billing 17110 with multiple units is a common overpayment.