Many small procedures, each with its own rules
A single dermatology visit can include an evaluation, several biopsies using different techniques, destruction of premalignant lesions and an excision — each coded by lesion, method, size or count. Most of these are minor procedures with a 0- or 10-day global period, so whether the visit itself can also be billed depends on what else was done and documented. Errors here are common because every lesion is a separate coding decision.
Biopsies, destructions and excisions
| Service | Coded by | Common codes |
|---|---|---|
| Skin biopsy | Technique (tangential, punch, incisional); first lesion plus each additional | 11102–11107 |
| Destruction of premalignant lesions | Number of lesions | 17000, 17003, 17004 |
| Destruction of benign lesions (e.g. warts) | Number of lesions | 17110, 17111 |
| Excision, benign or malignant | Excised diameter including margins, and anatomic site | 11400–11471, 11600–11646 |
| Repair after excision | Repair type (intermediate, complex) and total length per site group | 12031–12057, 13100–13153 |
Excision codes depend on the lesion’s diameter plus the narrowest margins, measured before excision — a measurement that must be in the note. Malignant or benign status comes from pathology, so excisions are usually coded once the pathology report is back. A simple repair is included in the excision; intermediate and complex repairs are billed separately.
Modifiers on the same day
- Modifier 25: the decision to perform a minor procedure is part of the procedure, so a same-day E/M is billable only for a significant, separately identifiable service — for example, managing a different problem.
- Modifier 59 or XS: used when procedures that normally bundle are performed on separate lesions or sites, as the documentation supports.
- Multiple procedures: the order of lines and modifier 51 affect payment when several procedures are performed in one session.
Mohs surgery and pathology
In Mohs micrographic surgery (17311–17315) the same physician removes the tissue and examines it, so the codes include both roles; separate surgical pathology for the same tissue is not billed. Codes depend on the anatomic area, the stage and the number of tissue blocks, and many payers apply appropriate-use criteria for Mohs. Practices with an in-house lab bill dermatopathology (for example 88305) with the correct professional and technical components.
Cosmetic or medically necessary
Removing a benign lesion only for appearance is cosmetic and not covered. When a lesion is symptomatic — bleeding, irritated, inflamed or suspicious — the note must say so for the removal to be covered. Medicare does not cover cosmetic services by law; modifier GX can show that a voluntary notice was given, and patients should agree to self-pay pricing before the service.
Biologics and phototherapy
Treatments for psoriasis, atopic dermatitis and hidradenitis often require prior authorization with documentation of severity and earlier therapies, and renewals on a schedule. Phototherapy (96910–96922) is billed per session and often limited by payer policy. See prior authorization services.