Dermatology Billing 2026 Mohs Surgery, Biopsy Coding & E/M Split Billing

Why Dermatology Billing Demands Precision in 2026

Dermatology is one of the highest-revenue specialties per encounter, but it is also one of the most audit-prone. Mohs micrographic surgery, skin biopsies, destruction of lesions, and E/M services frequently overlap in a single visit, creating a billing landscape where one modifier error or one missing pathology report can trigger a five-figure recoupment.

In 2026, CMS has continued to refine its policies on same-day E/M billing with procedures, Mohs surgery documentation requirements, and biopsy code selection based on technique. Payers are increasingly using AI-driven audit tools to flag dermatology claims for review, making clean first-pass submission more critical than ever.

This guide covers the three pillars of dermatology billing complexity: Mohs surgery, biopsy coding, and E/M split billing -- with the specific CPT codes, modifiers, documentation rules, and denial prevention strategies your practice needs.

Mohs Micrographic Surgery Billing

Mohs surgery is the most technically complex and highest-reimbursement procedure in dermatology. The CPT code structure is based on the number of stages, tissue blocks, and anatomic location. Correct billing requires understanding the distinction between the first stage, additional stages, and the unique block-based reporting system.

Mohs Surgery CPT Codes

CPT Code	Description	Key Rule
17311	Mohs, first stage, up to 5 tissue blocks, head/neck/hands/feet/genitalia	Primary code; includes histopathologic exam
17312	Each additional stage, up to 5 blocks (add-on to 17311)	Same lesion, same anatomic group as 17311
17313	Mohs, first stage, up to 5 tissue blocks, trunk/arms/legs	Different rate from 17311; lower RVU
17314	Each additional stage, up to 5 blocks (add-on to 17313)	Same lesion, trunk/arms/legs
17315	Each additional block beyond 5, any stage (add-on)	Add-on to 17311-17314; per block

Mohs Billing Rules -- Critical Points

Surgeon as Pathologist: Mohs surgery is unique because the surgeon acts as both surgeon and pathologist. The CPT codes include the histopathologic examination of margins. Do NOT separately bill pathology codes (88302-88309) for the Mohs margin examination -- this is already included in 17311-17314.

Stage vs. Block: A stage consists of the excision plus microscopic examination of the margins. Each stage can involve up to 5 tissue blocks. If more than 5 blocks are needed in a single stage, bill 17315 for each additional block. The average Mohs case requires 1.7 stages.

Multiple Lesions: When Mohs is performed on multiple separate lesions on the same day, report 17311 or 17313 for the first stage of each lesion. Append modifier -59 (distinct procedural service) to the second and subsequent lesion's first-stage code to prevent bundling denials.

Reconstruction Billing: Wound repair after Mohs is billed separately using repair codes (12031-14302 for intermediate/complex repair, or flap/graft codes). The repair is NOT included in the Mohs codes. Always document the repair as a separate operative note.

ICD-10 Codes for Mohs-Eligible Lesions

ICD-10 Code	Description	Common Location
C44.311	Basal cell carcinoma of skin of nose	Most common Mohs indication
C44.319	BCC of other parts of face	Eyelid, ear, lip margin
C44.41	BCC of skin of scalp and neck	High-risk scalp tumors
C44.511	Squamous cell carcinoma of skin, lip	SCC lip margin
C44.521	SCC of skin of ear and external auricular canal	Ear SCC
C44.310-C44.399	BCC by site (nose, eyelid, ear, face, scalp, trunk, limbs)	Site-specific BCC
C44.510-C44.599	SCC by site	Site-specific SCC
D04.0-D04.9	Carcinoma in situ of skin	When Mohs is used for CIS

CMS Article A53883: The CMS Billing and Coding Article for Mohs Micrographic Surgery outlines covered indications, required documentation, and reporting guidelines for Medicare claims.

Skin Biopsy Coding: Technique-Based Code Selection

Effective January 1, 2019, CMS restructured skin biopsy codes to be technique-based rather than site-based. This means the code selection depends on HOW the biopsy was performed (tangential, punch, incisional), not WHERE it was taken from. This change continues to cause coding errors in dermatology practices that have not fully adapted their workflows.

Biopsy CPT Codes by Technique

CPT Code	Description	Technique	Billing Rule
11102	Tangential biopsy (shave), single lesion	Shave/scoop/saucerize	First lesion; primary code
11103	Tangential biopsy, each additional lesion	Shave add-on	Add-on to 11102
11104	Punch biopsy, single lesion	Circular blade punch	First lesion; primary code
11105	Punch biopsy, each additional lesion	Punch add-on	Add-on to 11104
11106	Incisional biopsy, single lesion	Scalpel incision through dermis	First lesion; primary code
11107	Incisional biopsy, each additional lesion	Incisional add-on	Add-on to 11106

Biopsy Billing Rules

One Primary + Add-Ons: When multiple biopsies are performed on the same day, bill one primary code (11102, 11104, or 11106) for the first lesion biopsied, and use the corresponding add-on code for each additional lesion. You may only bill ONE primary biopsy code per encounter.

Mixed Techniques: If you perform a shave biopsy on one lesion and a punch biopsy on another, bill the primary code for the first lesion biopsied and the add-on code corresponding to the technique used for each subsequent lesion. Example: first lesion shave (11102) + second lesion punch (11105).

Biopsy + Excision Same Lesion: If a biopsy and excision are performed on the SAME lesion during the same encounter, only bill the excision (11600-11646 for malignant, 11400-11446 for benign). The biopsy is bundled into the excision when performed on the same lesion, same date.

Pathology: Skin biopsies require a separate pathology interpretation. If the dermatologist personally interprets the pathology slides, bill 88305 (surgical pathology, Level IV) separately. If sent to an outside lab, the lab bills the pathology.

E/M Split Billing: When to Bill an Office Visit with a Procedure

Same-day E/M billing with dermatologic procedures is one of the most audited areas in all of medicine. The key question: when does the decision to perform a procedure constitute a separately billable E/M service? The answer hinges on modifier -25 and the documentation to support it.

The Modifier -25 Rule

When Modifier -25 Applies: An E/M service (99202-99215) may be billed on the same day as a minor procedure (global period 0 or 10 days) ONLY when the E/M represents a significant, separately identifiable service beyond the decision to perform the procedure.

What Qualifies: The patient presents with a complaint or condition that requires independent medical decision-making beyond simply examining the lesion being biopsied or treated. Examples: a patient comes in for a suspicious mole (biopsy) but also has a new rash requiring diagnosis and treatment plan, or a patient with actinic keratosis destruction also needs a full skin cancer screening with documentation of medical history, multi-system exam, and management plan.

What Does NOT Qualify: Simply documenting a review of systems or examining the lesion before deciding to biopsy does NOT justify a separate E/M. The pre-procedure evaluation is part of the procedure itself.

Documentation Requirements for E/M + Procedure

• Separate and distinct chief complaint or problem addressed by the E/M service

• Documented medical decision-making for the E/M that goes beyond the procedure decision
• Clear separation in the note between the E/M portion and the procedure portion
• The E/M level must be supported by the documented complexity of the non-procedural problem
• Modifier -25 appended to the E/M code on the claim

Common E/M Split Billing Scenarios in Dermatology

Scenario	Bill E/M?	Rationale
Patient presents for suspicious mole; biopsy performed	NO	Evaluation of the mole is part of the biopsy decision
Patient presents for mole biopsy + new eczema flare requiring treatment plan	YES with -25	Eczema is a separate condition requiring independent MDM
Cryotherapy for 5 actinic keratoses + comprehensive skin cancer screening	YES with -25	Full screening with ROS, exam, and management is separate from destruction
Follow-up for pathology results + excision of confirmed BCC	YES with -25	Path review discussion and excision are distinct services
Patient presents for acne follow-up + shave biopsy of incidental lesion	YES with -25	Acne management is the primary reason for visit; biopsy is incidental

 

 

Lesion Destruction: Premalignant and Benign Codes

Destruction of skin lesions (cryotherapy, electrodesiccation, curettage) is among the most common dermatology procedures but carries specific counting rules that differ between premalignant and benign lesions.

Destruction CPT Codes

CPT Code	Description	Counting Rule
17000	Destruction, premalignant lesion (e.g., actinic keratosis), first lesion	First premalignant lesion
17003	Destruction, premalignant, 2nd through 14th lesion, each	Per lesion; add-on to 17000
17004	Destruction, premalignant, 15 or more lesions	Flat fee; replaces 17000+17003 when 15+
17110	Destruction, benign lesions other than skin tags, up to 14 lesions	Flat fee regardless of count (1-14)
17111	Destruction, benign lesions, 15 or more	Flat fee for 15+ benign lesions
17106-17108	Destruction, cutaneous vascular proliferative lesions	By size: <10, 10-50, >50 sq cm

Critical Distinction: Premalignant lesions (actinic keratoses) are counted individually (17000 + 17003 x number), while benign lesions are billed as a flat fee regardless of count (17110 for 1-14). Mixing up these counting systems is a common audit finding.

Biopsy + Destruction Same Lesion: If you biopsy a lesion and then destroy the remaining tissue at the same visit, only bill the biopsy code. Destruction of the biopsy site is included in the biopsy procedure.

Top 5 Dermatology Denial Triggers

1. Modifier -25 Abuse on E/M Claims

Payers flag practices with -25 modifier usage rates above 50% of procedural encounters. If your practice appends -25 to every procedure day, expect audits. Only bill E/M when truly separate conditions are managed and documented independently from the procedure.

2. Biopsy + Excision Same Lesion Bundling

Billing 11102 (shave biopsy) and 11600 (malignant excision) for the same lesion on the same date is a bundling violation unless the biopsy was performed on a prior date and the excision is performed after pathology confirmation. Same-day biopsy + excision of the same lesion = excision code only.

3. Mohs Pathology Double-Billing

Billing 88305 (surgical pathology) alongside Mohs codes (17311-17314) for the same tissue examined during Mohs surgery. The pathology is already included in the Mohs code. Only bill separate pathology for tissue sent to an outside pathologist (e.g., permanent sections of the deep margin after Mohs).

4. Incorrect Lesion Count for Destruction

Billing 17000 + multiple 17003 units for benign lesions (which should use 17110 flat fee) or billing 17110 for premalignant lesions (which should use 17000 + 17003). Know the diagnosis before selecting the destruction code series.

5. Missing Site-Specific ICD-10 for Skin Cancer

Using unspecified site codes (C44.90 -- unspecified malignant neoplasm of skin) instead of anatomically specific codes (C44.311 -- BCC of nose). Unspecified codes trigger higher denial rates and audit scrutiny. Always report the most specific anatomic location code available.

Let 24/7 MBS Maximize Your Dermatology Revenue

Dermatology billing requires subspecialty-level coding knowledge that general billing teams simply do not have. From Mohs stage-and-block reporting to biopsy technique selection to E/M split billing compliance, 24/7 Medical Billing Services has the certified dermatology coders and audit-ready documentation processes your practice needs.

Our dermatology billing specialists review every claim for NCCI edit compliance, modifier accuracy, and proper code sequencing before submission -- eliminating the most common denial triggers before they reach the payer.

Schedule a Free Dermatology Billing Audit

888-502-0537  |  www.247medicalbillingservices.com

FAQs

What are the key Dermatology Billing 2026 updates?

Dermatology Billing 2026 includes coding updates for Mohs surgery, biopsy procedures, modifier usage, and E/M split billing documentation requirements.

How is Mohs surgery billed in 2026?

Mohs surgery is billed using CPT codes based on the anatomical site, number of stages performed, and tissue blocks processed during the procedure.

Can skin biopsy and E/M services be billed together?

Yes, dermatologists can bill biopsy procedures with E/M services when documentation supports a separately identifiable evaluation using modifier -25.

What modifier is used for separate dermatology E/M billing?

Modifier -25 is commonly used when a significant and separately identifiable E/M service is performed on the same day as a dermatology procedure.

Are biopsy coding rules changing in Dermatology Billing 2026?

Dermatology Billing 2026 emphasizes accurate lesion documentation, biopsy technique selection, and medical necessity to avoid payer denials.

What documentation is needed for Mohs surgery claims?

Providers should document lesion location, pathology confirmation, surgical stages, tissue mapping, and reconstruction details for compliant billing.

Why do dermatology claims get denied frequently?

Common reasons include incorrect modifiers, insufficient documentation, unbundling errors, and inaccurate biopsy or Mohs coding.

How can dermatology practices improve reimbursement in 2026?

Practices can improve reimbursement through accurate coding, updated billing workflows, payer-specific compliance checks, and clean claim submission processes.