Reference
Dermatology Procedure Coding Guides
Skin biopsies, lesion destruction, excisions and repairs, Mohs stages and blocks, and the cosmetic-versus-medical split — what decides the code for each, and what the note has to record for it to hold.
Guides in this section
Skin biopsy
Skin Biopsy Coding: 11102 to 11107 in Dermatology Billing
How to code skin biopsies correctly: tangential, punch and incisional families, primary versus add-on units, and why the technique in the note decides the code, not the lesion.
Lesion destruction
Lesion Destruction Coding: 17000, 17003, 17004 and 17110
Destruction of premalignant and benign lesions coded correctly: 17000 and 17003 unit stacking, when 17004 replaces them, and how 17110 and 17111 differ.
Excisions and repairs
Excision and Repair Coding in Dermatology
Benign and malignant excision coding by site and excised diameter, plus when simple, intermediate and complex repairs are separately reportable.
Mohs surgery billing
Mohs Surgery Billing and Coding (17311-17315)
Mohs micrographic surgery coding explained: first stage versus additional stages, tissue block add-ons, what is bundled into the Mohs code, and how repairs are reported.
Cosmetic vs medical
Cosmetic Versus Medical Dermatology Billing
How to separate cosmetic self-pay work from medically necessary dermatology on the same visit: consent, financial disclosure, coding and the compliance line you cannot cross.
Phototherapy
Phototherapy Billing (96900, 96910, 96920-96922)
Phototherapy billing for dermatology: actinic therapy 96900, UVB with tar 96910, laser 96920-96922, home unit supervision, and the documentation each treatment session needs.
Biologics and injectables
Biologics and Injectable Billing (J-codes, 96372, 96401)
Billing dermatology biologics and injectables: J-code units, administration codes 96372 and 96401, buy-and-bill versus specialty pharmacy, wastage, and prior authorization.
Skin substitutes
Skin Substitute Application Billing (15271-15278)
Skin substitute application coding for dermatology: the 15271-15278 body-area and wound-size structure, product Q-codes, wastage, and the coverage documentation payers require.
Teledermatology
Teledermatology Billing: Codes, Modifiers and Place of Service
How teledermatology is billed: synchronous video E/M, store-and-forward, e-visits and remote review codes, place of service 02 versus 10, and modifiers 95, GT and GQ.
Patch testing
Patch Testing Billing: 95044 Units and Reading Visits
Patch testing billing in dermatology: how 95044 units are counted per allergen, how the application and reading visits are reported, and what payers require for coverage.
Dermatopathology
Dermatopathology Billing: 88304-88342 and Component Splits
Dermatopathology billing explained: specimen-level unit counting under 88304 and 88305, special stains and immunohistochemistry, and global versus TC and 26 component billing.
How dermatology procedure coding works
Dermatology procedure coding is the process of translating what was done to the skin into CPT and HCPCS codes, and in this specialty the code is almost never chosen from the diagnosis. It is chosen from four things recorded during the procedure: the technique used, the number of lesions or sites treated, a measurement taken before the tissue was altered, and the intent — diagnostic sampling versus definitive removal versus destruction.
Those four inputs behave differently across the code families. Biopsies are selected by technique and stacked with per-lesion add-ons. Destruction is selected by lesion type and paid by unit count. Excisions are selected by the excised diameter, which includes the margins and must be measured before fixation shrinks the specimen. Repairs are classified by layers and summed length within the same anatomic grouping. Mohs is counted by stage and by tissue block. Injections, phototherapy and skin substitutes each carry their own unit definition again.
Where the code is actually decided
- In the room, when a measurement is taken or not taken. A number that was never written cannot be recovered by a coder later.
- In the specimen container, because a specimen is defined as tissue that can be separately diagnosed — two lesions in one jar is one unit.
- In the note template, when a default closure type or a pre-filled modifier turns a per-case judgement into a standing pattern.
- At charge entry, when an add-on unit count is left at one because the field the clinician filled is not the field the charge reads.
- In the payer's coverage article, which decides whether a correctly coded service is payable at all in your jurisdiction.
Why dermatology procedure coding leaks money quietly
Most specialties lose revenue to denials, which are visible. Dermatology loses most of its revenue to undercoding, which is not. A destruction billed at one unit when nine lesions were treated pays cleanly. An excision coded from the lesion diameter instead of the excised diameter pays cleanly. A sixth Mohs block never reported pays cleanly. Nothing in the remittance says anything is wrong.
That is why these guides are written around the measurement and the count rather than around the code list. The code is almost never the hard part — the hard part is whether the number that drives it was captured in the room, in a field a biller can see.
How to use these guides
- Each guide covers what determines the code, what the note must record, and where the common error sits.
- Documentation requirements are written as what the record must show, not as phrases to paste into a template.
- Undercoding and overcoding are treated as equally serious. One costs you money now, the other costs you more later.
- These are references, not coding advice for a specific claim. Payer policy varies by contract and by MAC jurisdiction, and it changes.
Frequently asked questions
Which dermatology procedure is most often coded wrong?
Lesion destruction, because the add-on unit count is the whole value of the claim and it depends on a number being carried from the note to the claim intact.
Do you review how our practice currently codes these?
Yes. The free claims audit samples recent claims against the documentation behind them and reports undercoding as well as risk, since undercoding is usually the larger number.
Can our providers use these guides directly?
They are written for that. The documentation sections are the ones worth putting in front of clinical staff, because that is where the code is actually decided.