Dermatology billing that keeps medical and cosmetic work separate.

Dermatology medical billing turns on lesion count, size, and a clear line between medically necessary and cosmetic work. One afternoon can include a necessary excision, destructions, a cosmetic filler, and a Mohs case. Mixing those charges on one claim leads to denials and refunds — often months later, after the patient already paid cash for the cosmetic portion.

Destructions and the lesion-count ladder

Destruction of premalignant lesions typically starts with 17000 for the first lesion and 17003 for each additional lesion through 14; 17004 covers 15 or more in a single session. Benign destruction codes sit in a different family (often 17110/17111 depending on count). Mixing premalignant and benign counts on the wrong CPT is a frequent scrubber catch. Document lesion type and count clearly — “treated several AKs” is not a billable count.

Excisions by size and margin, biopsies, and Mohs

Excision codes (11400–11446 for benign, 11600–11646 for malignant) are selected by anatomic site and excised diameter including margins, not by lesion size alone. Measure clinically before excision; pathology size does not replace clinical measurement for CPT selection. Biopsy codes 11102–11107 distinguish tangential, punch, and incisional techniques with add-ons for additional lesions. Do not bill a biopsy when intent and documentation support a full excision.

Mohs micrographic surgery uses 17311 for the first stage on head, neck, hands, feet, and genitalia (17313 for trunk/arms/legs), with 17312 / 17314 for additional stages. Each stage needs documented tissue maps and histopathologic examination by the surgeon. Repair codes may be separately billable when intermediate or complex repair is performed and not bundled by payer policy — check NCCI before stacking.

• Count lesions by type before selecting 17000/17003/17004 vs benign destruction codes.
• Select excision CPTs using excised diameter including margins, by site.
• Use 11102–11107 only when the procedure is a biopsy, not a definitive excision.
• Keep cosmetic charges on self-pay tickets — never on the insurance claim with medical CPT codes.

Cosmetic vs medical: separate the cash lane

Cosmetic services (elective destruction of benign lesions without medical necessity, aesthetic injectables, laser packages) should never ride an insurance claim “to see if it pays.” That habit creates false A/R, patient refunds, and compliance risk. Our dermatology medical billing workflows use separate ticket types and posting rules so cosmetic cash cannot contaminate medical ERA posting. Medical necessity diagnoses must match the procedure; “patient desires removal” is not a covered indication for most plans.

Pathology timing matters when you hold claims for results. Bill the procedure when performed; bill professional pathology when the interpretation is complete. Holding the excision claim for two weeks until pathology returns ages A/R without cause. A dermatology medical billing company should post both sides cleanly, keep first-pass rates at 97%+, and update malignant diagnoses without rewriting history on the original date of service. Days in A/R should stay under 28 even in a Mohs-heavy month.