Question: A patient returns for surgery after remaining symptomatic following a simple mastoidectomy. The surgeon performs a revision mastoidectomy, resulting in a conversion to a complete mastoidectomy. Afterwards, the surgeon documents the placement of an Alloderm® graft in the mastoid bowl as a means of soft tissue reinforcement underneath the skin. What’s the CPT® coding? Ohio Subscriber Answer: You may come across the use of an acellular dermal matrix (ADM) such as Alloderm® during mastoidectomy revisions in addition to a wide variety of other ENT reconstruction and revision surgeries. However, there’s a great deal of confusion as to how you should code an ADM when placed underneath a dermal layer for reinforcement purposes. Code 15275 (Application of skin substitute graft to face, scalp, eyelids, mouth, neck, ears, orbits, genitalia, hands, feet, and/ or multiple digits, total wound surface area up to 100 sq cm; first 25 sq cm or less wound surface area) is inappropriate since this scenario does not involve the placement of skin substitute graft. Furthermore, code +15777 (Implantation of biologic implant (eg, acellular dermal matrix) for soft tissue reinforcement (ie, breast, trunk) (List separately in addition to code for primary procedure)) meets the surgical criteria of what you’re looking for, but the anatomic sites don’t align. Instead, you’ll have to resort to reporting the unlisted code 17999 (Unlisted procedure, skin, mucous membrane and subcutaneous tissue) and submitting the claim on paper with the appropriate documentation. You may also use code +15777 as a reference code for reimbursement purposes.