Coding
Mohs micrographic surgery
A staged skin cancer excision in which the same physician acts as surgeon and pathologist, billed by stage and by additional tissue block.
What it means in dermatology
Mohs is reported with a first-stage code for the anatomic area (17311 or 17313) and an additional-stage code for each subsequent stage (17312 or 17314), plus 17315 for each block beyond the first five within a single stage. The defining requirement is that one physician performs both the excision and the microscopic examination during the same session.
Because the codes describe stages rather than time or lesion size, the operative note has to make the stage sequence explicit. A note that describes the case narratively without numbering stages and blocks is the most common reason a correctly performed Mohs case gets underpaid or denied on review.
Why it matters to your revenue
Mohs is the single largest revenue line in most surgical dermatology practices, so a stage-counting habit that is off by one on a fraction of cases costs more than every small-balance denial combined.
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