Biopsies, destructions and the add-on unit rules
Skin biopsies are reported by technique. A tangential shave is 11102 for the first lesion and 11103 for each additional, a punch is 11104 and 11105, and an incisional biopsy is 11106 and 11107. When techniques are mixed, only the most complex primary code is reported and the remaining lesions go on add-ons, so two primary biopsy codes on one claim hit an edit however they are modified.
Destruction follows a different ladder. Actinic keratoses are 17000 for the first, 17003 for each of the second through fourteenth, and 17004 alone at fifteen or more. Warts are 17110 or 17111 by count, and malignant destruction uses 17260 to 17286 by site and size. The note must state count and diagnosis for each group, or the add-on units draw a medically-unlikely-edit denial.
Excisions are sized by the specimen and coded by the pathologist
Excision codes are chosen by excised diameter, the lesion plus the narrowest margin on each side measured before the specimen leaves the room, and by body area. Benign excisions run 11400 through 11446 and malignant excisions 11600 through 11646. Only the pathology result decides between the families, so we hold every excision claim until the path report posts.
A repair is separately reportable only when it is intermediate, 12031 through 12057, or complex, 13100 through 13153; a simple closure is included in the excision. Repair length is summed across wounds in the same anatomic group and complexity class rather than listed per wound, so adding repairs one line at a time overstates the claim.
Mohs surgery and the surgeon-as-pathologist requirement
Mohs is 17311 for the first stage and 17312 for each additional stage on the head, neck, hands, feet and genitalia, with 17313 and 17314 for the trunk and extremities. The codes assume one physician acts as both surgeon and pathologist and reads the frozen sections personally. If a separate pathologist reads the slides, the case is not Mohs for billing purposes and is reported as an excision with pathology.
A biopsy on the same day as Mohs is separately payable only when there was no prior pathologic diagnosis and the note explains why the frozen-section result was needed first; it carries modifier 59. The reconstruction that follows is reported on its own and holds much of the reimbursement, so we reconcile the closure code to the operative note before submission.
Modifier 25 and the same-day visit, the most audited pattern in derm
A skin check that finds a suspicious lesion, biopsies it and adjusts the patient’s acne regimen is a legitimate E/M plus procedure, and modifier 25 on the visit says so. Payers see 25 on nearly every dermatology claim and audit it accordingly. Examining and deciding about the lesion that was biopsied belongs to the procedure and cannot support the visit.
Our coders apply 25 only when the note shows a different problem, a medication change or a total-body examination with findings beyond the treated lesion; otherwise we bill the procedure alone. For distinct lesions treated by different methods, modifier 59 or the more specific XS marks the separate site, and the lesion map in the note is what makes it hold on appeal.
Cosmetic versus medically necessary, settled before the patient leaves
Skin tag removal under 11200, seborrheic keratosis treatment, spider vein sclerotherapy and many cyst removals are cosmetic by default and covered only when the note documents irritation, bleeding, obstruction or suspicious change. Payers apply that rule at the claim edit, after the patient has left, and the practice writes off a service it could have collected at the desk.
We build the cosmetic screen into scheduling and check-in. When a service is unlikely to be covered, Medicare patients sign an ABN and commercial patients sign a self-pay agreement showing the fee, and the claim carries the modifier reporting that the patient accepted responsibility. Where necessity exists, the documented symptom and matching diagnosis go on the claim.
How we take on dermatology billing
We begin with a free A/R review that sorts your aging the way dermatology bills: biopsy and destruction claims stuck on units, excisions waiting on pathology, Mohs reconstructions denied, biologics waiting on authorization and cosmetic write-offs that should have been patient balances. Our coders hold AAPC or AHIMA credentials, the BAA is executed before any record is shared, and we work inside the practice management and EHR you already use.
The handoff is a parallel period of two to four weeks in which the outgoing biller and our team code the same encounters, and the differences become your written policy on modifier 25, lesion counts and repair bundling. After the initial term the contract continues month to month, with a named account manager who learns your payers and your lab arrangement.
