Excision and Repair Coding in Dermatology

How excised diameter is actually calculated

The measurement is lesion diameter plus twice the narrowest margin taken. A 0.8 cm lesion excised with 0.5 cm margins is a 1.8 cm excision, not a 0.8 cm one — and those fall in different code brackets with materially different payment. The measurement is taken in the room, before excision, while the tissue is still in its natural state.

Measuring from the pathology report systematically undersizes the code, because formalin fixation shrinks tissue and the pathologist measures the specimen, not the surgical field. Where the only measurement in the chart came from pathology, the correct response is a template change that captures the pre-excision measurement, not an upward adjustment of the pathology figure.

Benign, malignant and the pathology timing problem

Benign excisions run in the 11400 to 11446 range and malignant excisions in the 11600 to 11646 range, both subdivided by site group — trunk/arms/legs, scalp/neck/hands/feet/genitalia, and face/ears/eyelids/nose/lips. Malignant excision pays substantially more, and the difference is decided by a pathology report that usually arrives after the encounter is closed.

The correct practice is to hold the charge until pathology returns, then code to the final diagnosis. Practices that bill benign on the day and never revisit the claim leave the malignant differential unclaimed on every skin cancer they excise; practices that bill malignant in anticipation create a refund liability. A held-charge worklist reconciled against returned pathology is the control that resolves both.

When a repair is separately reportable

• Simple repair is included in the excision code and is never separately reported. A single-layer closure of the excision defect is simple repair.
• Intermediate repair — layered closure involving deeper subcutaneous tissue or superficial fascia, or single-layer closure of a heavily contaminated wound requiring extensive cleaning — is separately reportable when documented as layered.
• Complex repair requires more than layered closure: scar revision, debridement, extensive undermining, stents or retention sutures. The note must describe what made it complex rather than asserting complexity.
• Adjacent tissue transfer and flap codes include the excision. Reporting the excision separately alongside a flap is a bundling error, not an additional charge.

Multiple excisions in one session

Each lesion excised is reported separately with its own code reflecting its own site and its own excised diameter. Diameters are never summed across lesions. Where two excisions fall in the same code, the second is reported as an additional unit or a second line with the appropriate distinct-service modifier depending on payer preference, and each needs its own documented site.

Repairs behave differently: repairs of the same classification in the same anatomical group are summed in length and reported as a single code. Summing repairs across classifications or across anatomical groups is an overcode, and failing to sum within a group is an undercode.