Mohs micrographic surgery uses CPT codes 17311 (first stage, including up to 5 tissue blocks) and 17312 (each additional stage beyond the first). Repair of the surgical defect is billed separately using closure codes (12031-14302, depending on size and location). Mohs is not subject to multiple procedure reduction when billed with repair codes. Requires a qualified Mohs surgeon (dermatologist with Mohs training). Facial lesions are auto-approved by most payers; trunk and extremity lesions typically require prior authorization. Documentation of tumor location, size, histology, and final margin status is essential for claim approval.
Bill 17311 once per Mohs procedure (represents first stage with up to 5 tissue blocks). For each additional stage beyond the first, bill 17312. A typical 3-stage procedure bills as 17311 × 1 + 17312 × 2. Document the number of stages and blocks clearly. If the tumor is excised in one stage (rare), bill 17311 only. Repair codes (12031-12057 for simple closure, 12100-12107 for intermediate, 13100-13160 for complex) are billed separately based on wound size, depth, and location. Use the tumor's ICD-10 code (C43.x for melanoma, C44.x for non-melanoma) as the primary diagnosis.
Facial Mohs (face, ears, eyelids, scalp) is auto-approved by virtually all payers without prior auth. Non-facial Mohs (trunk, arms, legs) requires prior authorization. Submit the lesion location, size, clinical diagnosis (melanoma, basal cell, squamous cell), and clinical indication for Mohs vs. standard excision. Most payers approve non-facial Mohs for high-risk tumors (recurrent, perineural invasion, aggressive histology) or cosmetically sensitive areas. Standard excision is considered adequate for most low-risk lesions. Verify your patient's coverage before scheduling.
Mohs codes and repair codes are not bundled. Bill both on the same claim without modifier 51 (multiple procedure reduction). Do not apply modifier 25 to the Mohs code—it is the primary service. If pathology is performed by an outside lab and billed separately (CPT 88305), do not apply modifiers; coordination with pathology billing is required to avoid duplicate charges. Do not use modifiers 26 or 59 with Mohs codes. Simple closure is sometimes included in skin cancer removal codes; verify that the repair code selected accurately reflects the reconstruction complexity and is not already included.
Document the lesion's location (anatomical site), pre-operative size (length and width), and clinical diagnosis. Record the histopathologic findings from each stage (positive margins, negative margins, tumor thickness). Document the number of stages and tissue blocks processed. Include a description of the final reconstruction: closure type (primary linear, flap, graft), suture material, and anticipated cosmetic outcome. Note the Mohs surgeon's credentials (board certification in dermatology and Mohs surgery training). Attach pathology reports and final margins documentation. For prior auth requests, clearly state why Mohs was chosen over standard excision (tumor characteristics, location, recurrence risk).
Each lesion is coded separately. Bill 17311 for the first lesion and 17312 for each additional lesion's additional stages. If a second lesion requires 2 stages, bill 17311 (first lesion) + 17312 × 2 (additional lesion stages). Include the location of each lesion in the documentation to distinguish them.
The treating physician makes the clinical decision based on tumor characteristics (histology, size, location, recurrence risk), patient factors, and cosmetic considerations. Payers defer to the clinician's judgment for facial lesions. For non-facial lesions, payers may require justification for Mohs over standard excision. Document the clinical rationale in the operative note.
Yes. Bill 17311 once. The code includes up to 5 blocks and represents the surgical procedure regardless of the number of positive/negative margins. One-stage Mohs (clear margins on first attempt) is still a Mohs procedure and bills 17311.
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