Dermatology is one of the most modifier-25-intensive specialties in U.S. medicine, and CMS Comprehensive Error Rate Testing data continues to flag it among the top error categories. The 2026 CPT code set retained the consolidated biopsy structure (11102 through 11107) introduced in 2019, kept the destruction codes (17000-17004 for premalignant lesions, 17110-17111 for benign lesions), and adjusted certain excision descriptors. For dermatology practices, the 2026 billing playbook is dominated by three patterns: biopsy method coding discipline, modifier 25 documentation when E/M is billed alongside a procedure, and the surgical pathology coordination with the lab.
The biopsy code structure
The consolidated 2019-and-after biopsy structure assigns codes by biopsy method, not by lesion site:
- 11102: tangential biopsy, single lesion (epidermal layer only).
- 11103: each additional tangential biopsy (add-on to 11102).
- 11104: punch biopsy, single lesion.
- 11105: each additional punch biopsy (add-on to 11104).
- 11106: incisional biopsy, single lesion (deeper, full-thickness sample).
- 11107: each additional incisional biopsy (add-on to 11106).
Method documentation matters
Documentation must specifically describe the biopsy method to support the code billed. A note that says “biopsy performed” supports nothing. A note that says “shave biopsy with a number 15 blade, removing the elevated portion of the lesion” supports a tangential biopsy (11102). A note that says “3 mm punch biopsy taken from the central pigmented area” supports a punch biopsy (11104). A note that says “elliptical incision down to subcutaneous tissue, removing a wedge for histology” supports an incisional biopsy (11106). When multiple biopsies are taken at the same encounter, the add-on codes (11103, 11105, 11107) attach to the corresponding base code, and modifier 59 may be required when a different method is used at a different lesion.
Lesion destruction codes
Destruction codes apply when the lesion is destroyed without tissue sent for pathology. Premalignant lesions (actinic keratoses) use 17000 (first lesion) and 17003 (each additional 2-14, billed once with units), with 17004 reserved for 15 or more lesions billed once. Benign lesions (warts, molluscum, milia, skin tags, cherry angiomas) use 17110 (up to 14 lesions) or 17111 (15 or more lesions). Malignant lesion destruction uses 17260-17286 by site and size. The most common audit failure is destruction codes billed without documentation of the destruction method (cryotherapy, electrosurgery, chemical, laser) or the number of lesions treated.
Excision codes and the closure question
Lesion excision codes (11400-11646) are selected by lesion type (benign 11400-11471, malignant 11600-11646) and by site and excised diameter (lesion plus narrowest margins). Simple closure is included in the excision code. Intermediate closure (12031-12057, requiring layered closure of subcutaneous tissue and skin) and complex closure (13100-13160, requiring extensive undermining or scar revision) are billed separately. Documentation must specify the closure type performed; “closed primarily” without further detail typically defaults to simple closure for billing purposes. The opportunity for under-billing is the intermediate or complex closure that the documentation does not describe in enough detail to support the code.
Mohs surgery (17311 through 17315)
Mohs micrographic surgery codes apply when the same physician performs the surgical excision, prepares and reads the pathology, and continues until the margins are clear. Codes are selected by anatomic location (17311 for trunk, arms, legs, with first stage; 17312 for trunk add-on stages; 17313 for face, ears, eyelids, nose, lips, scalp, neck, hands, feet, genitalia, with first stage; 17314 for those add-on stages; 17315 for each additional block on the same stage). Mohs cannot be billed with separate excision or pathology codes for the same lesion at the same encounter. Documentation must establish that the surgeon performed both the surgery and the pathology interpretation in the same procedure.
Modifier 25 patterns specific to dermatology
Dermatology is one of the highest-volume modifier 25 specialties because patients commonly present with both a primary problem and an unrelated dermatologic concern. The audit-defensible modifier 25 case in dermatology has separate documentation for the E/M service and the procedure, with the E/M addressing a problem distinct from the procedure target. Patients arriving for a scheduled procedure with no other clinical concern should not generate a modifier 25 claim. Patients arriving for a check on a separate concern who also have a procedure performed at the same visit can support modifier 25 when the documentation establishes the distinct cognitive efforts.
How MHB helps dermatology practices
For dermatology practices that want specialty-trained coders working their biopsy, destruction, excision, Mohs, and modifier 25 claims, our team supports specialty medical coding for dermatology. The work runs in the practice’s existing EHR.
The bottom line
Dermatology billing rewards documentation specificity. Method-specific biopsy notes, destruction details, excision diameter and closure type, and disciplined modifier 25 use are the difference between full revenue capture and either denied claims or audit recoupment. Practices that build templates aligned to the code structures move at full margin. Practices that improvise leak revenue and absorb audit risk simultaneously.
Authoritative sources
This article cites the following primary sources for billing-code and regulatory guidance. Always confirm current rules and codes with the publishing authority before applying to a specific claim.
