Dermatology Billing in 2026

OIG Audit Risks, Surgical vs. Medical Coding, and Pathology Bundling

Published May 21, 2026 · 11 min read · By Yagnesh Dave

Dermatology generates more claim lines per patient encounter than almost any other outpatient specialty, an E/M visit, a biopsy, a destruction procedure, a pathology specimen, and a biologic injection can all occur in a single visit, each requiring a separate correctly coded claim line. The challenge is not volume; it is precision. Cosmetic vs. medical necessity disputes drive 22% of dermatology denials, while Mohs surgery coding errors, where documentation must support every individual tissue stage billed, account for the single highest dollar-value denial category in the specialty. Get this wrong at volume and the cost shows up fast, through denials, undercoding, or missed follow-up.

At RCMAXIS, our dermatology billing team handles coding for medical dermatology, procedural dermatology, Mohs surgery programs, and cosmetic practices with medical components. Here's the complete guide to what goes wrong, and how to fix it.

1. Lesion Removal: Shaving, Excision, and Size Documentation

Lesion removal coding is determined by three factors: the removal technique (shaving, excision, destruction), the lesion type (benign vs. malignant), and the lesion size including margins. The most common error is reporting the size of the lesion alone without adding the margin width, a mistake that consistently results in undercoding.

Shave Removal (11300–11313)

• Shave removal codes are size-based: 0.5 cm or less (11300), 0.6–1.0 cm (11301), 1.1–2.0 cm (11302), over 2.0 cm (11303)
• Size is measured as the single longest diameter of the lesion itself, no margin calculation needed for shave removal
• 11305–11313 apply to the scalp, neck, hands, feet, and genitalia (same size increments)

Excision: Benign (11400–11471) and Malignant (11600–11646)

• Excision codes require the total excised diameter: lesion size plus the narrowest margin on all sides
• Document the lesion diameter AND the planned margin width in the procedure note, "excised 1.2 cm lesion with 0.3 cm margins = 1.8 cm total excised diameter"
• Malignant excision codes (11600+) reimburse significantly higher than benign excision codes at comparable sizes, use the correct code based on the clinical working diagnosis and pathology result
• If pathology upgrades a benign-coded excision to malignant, rebill with the malignant code after the pathology report is received

2. Destruction of Lesions: AKs, Warts, and Benign Lesions

Destruction codes (cryotherapy, laser, chemical, electrosurgery) are frequently confused with excision codes. Destruction is used when no specimen is sent for pathology, if a specimen is sent, use the appropriate biopsy or excision code instead.

Destruction Code Reference

• 17000: Destruction of premalignant lesion (AK), first lesion
• 17003: Each additional 2–14 lesions (add-on), bill one unit per two additional lesions
• 17004: 15 or more premalignant lesions (replaces 17000 + 17003 when 15+ lesions are destroyed)
• 17110: Destruction of benign lesions, up to 14 lesions
• 17111: 15 or more benign lesions
• 17250: Chemical cauterization of granulation tissue

17000 and 17110 can't be billed together on the same date of service. AKs and benign lesions are distinct code families. However, destruction of different lesion types (AKs and seborrheic keratoses) can be billed on the same day with modifier 59 to indicate distinct services at separate anatomic sites.

3. Mohs Micrographic Surgery: Stage-by-Stage Documentation

Mohs surgery coding is the most documentation-intensive procedure billing in dermatology. Each stage must be individually documented with tissue mapping, histologic examination results, and the decision to proceed to the next stage. The number of stages billed is limited by the number of stages performed and documented, not by the complexity of the case.

Mohs Surgery Code Reference

• 17311: Mohs, first stage, up to 5 tissue blocks, head, neck, hands, feet, genitalia, or any location with prior surgery or radiation
• 17312: Each additional stage after the first, up to 5 tissue blocks (add-on to 17311)
• 17313: First stage, up to 5 blocks, trunk, arms, or legs
• 17314: Each additional stage (add-on to 17313)
• 17315: Each additional block beyond 5 per stage (add-on)

Documentation Requirements Per Stage

• Tissue map showing the orientation and section numbers of each block removed
• Pathology report for each stage showing clear vs. positive margins by section
• Surgical note documenting the clinical decision to proceed to an additional stage based on positive margins
• Final stage documentation confirming clear margins and wound closure plan

4. Cosmetic vs. Medical Necessity: The Critical Distinction

The single most important billing judgment in dermatology is whether a service is cosmetic (patient-paid, not covered by insurance) or medically necessary (billable to insurance). Billing cosmetic services to insurance is fraud. Failing to bill medically necessary services because they appear cosmetic is revenue loss. The distinction requires clinical and coding precision.

Always Non-Covered (Cosmetic)

• Chemical peels for cosmetic skin rejuvenation
• Botulinum toxin for cosmetic wrinkle reduction
• Laser hair removal
• Removal of benign lesions for cosmetic reasons without functional impairment
• Filler injections (hyaluronic acid, collagen)

Potentially Covered with Medical Necessity Documentation

• Removal of dermatofibromas, seborrheic keratoses, or skin tags when causing functional problems (irritation, bleeding, interference with clothing)
• Laser treatment of port wine stains or hemangiomas in functionally significant locations
• Botulinum toxin for hyperhidrosis (64650, J0585), covered when documented as severe primary axillary hyperhidrosis failing topical treatment
• Photodynamic therapy (96567) for field cancerization with multiple AKs

5. Biologic Therapy: Drug Billing and Prior Authorization

Biologic therapies for moderate-to-severe psoriasis, atopic dermatitis, and hidradenitis suppurativa represent the highest per-patient revenue opportunity in dermatology. Prior authorization management is the critical operational challenge, and failed PA workflows are the primary reason dermatology practices lose biologic revenue to specialty pharmacies.

Common Dermatology Biologic HCPCS Codes

• J0222: Dupilumab (Dupixent), per 200 mg, atopic dermatitis, asthma, prurigo nodularis
• J0897: Denosumab (Prolia/Xgeva), not dermatology-specific; verify indication
• J3358: Ustekinumab (Stelara), per 1 mg, psoriasis, psoriatic arthritis
• J0882: Ixekizumab (Taltz), per 80 mg, plaque psoriasis
• J0490: Secukinumab (Cosentyx), per 1 mg, psoriasis, psoriatic arthritis, AS

Bill the administration code (96372 for subcutaneous injection) plus the drug HCPCS code on the same claim. Ensure prior authorization covers both the drug and the administration, some payers authorize the drug through the pharmacy benefit and the administration through medical, creating a billing split that requires coordination.

6. Pathology Billing in Dermatology

When the dermatologist performs the pathology in-house (reading their own slides), both the surgical procedure and the pathology interpretation are billable. When pathology is sent out to an external laboratory, the dermatologist bills only the procedure, the external lab bills pathology under their NPI.

In-House Pathology Code Reference

• 88305: Level IV surgical pathology, the most common code for skin biopsies and excision specimens
• 88307: Level V, for complex specimens including sentinel lymph nodes, wide excisions with margins
• 88314: Special stain, each, when special stains (PAS, GMS, AFB) are performed on the specimen
• 88342: Immunohistochemistry, first antibody, for melanoma staging or lymphoma typing

RCMAXIS manages dermatology billing for practices across the full spectrum, from solo medical dermatologists to multi-site Mohs surgery programs. Our compliance auditing service includes a dedicated dermatology cosmetic vs. medical review that identifies services billed to payers that should be patient-pay, and vice versa. See our illustrative scenarios for examples of how revenue recovery work is structured.

7. OIG Work Plan: Dermatology Risk Areas for 2026

Dermatology shows up on the OIG Work Plan almost every year, and the 2026 update is no exception. The pattern is consistent: high procedure volume, borderline medical-necessity calls, and drug billing that's easy to get wrong at scale, exactly the mix auditors look for.

The lookback period on these reviews typically runs 36 months, which means a documentation habit that's been wrong since last year is still fully exposed today. Most practices don't find out until a payer requests records, by then the recoupment is already calculated.

What Dermatology Procedures Pay and What Errors Cost

A busy dermatology practice earns on volume, so small coding gaps compound. At the 2026 Medicare rate, destroying a premalignant lesion under 17000 pays $66.47 in the office, a simple shave under 11300 pays $96.53, and a larger malignant excision under 11600 pays $198.40.

Say 60 procedures a month lose the separate E/M or the add-on lesion code because of a missed modifier 25 or a wrong count. At an average of $66 each, that's $3,988 a month and $47,858 a year. The fix isn't more training in general. It's a charge capture checklist that asks, for every procedure visit, whether a separate E/M was documented and how many lesions were treated.

Frequently Asked Questions About Dermatology

How do you choose between shave removal, excision, and destruction codes?

The article explains that lesion removal codes depend on the technique, whether the lesion is benign or malignant, and the size including margins. Destruction is used when no specimen goes to pathology, and if a specimen is sent, the biopsy or excision code applies.

Can cosmetic procedures be billed to insurance?

No. The article is direct about this: a cosmetic service is patient-paid, and billing it to insurance is fraud. Medically necessary services can be billed, but the record has to show the medical reason.

How is pathology billed when the practice reads its own slides?

When the dermatologist performs the pathology in house, both the surgical procedure and the pathology interpretation are billable. When the specimen goes to an outside lab, the lab bills for the pathology instead.