E524 – Mohs micrographic surgery - additional cuts
OHIP Surgical Assists Code — INTEGUMENTARY SYSTEM SURGICAL PROCEDURES · Schedule of Benefits
This fee is an add-on to `R081` for one or more additional cuts performed during Mohs micrographic surgery. Mohs micrographic surgery is eligible for payment when rendered for a lesion that is a histologically confirmed cutaneous malignancy (including basal cell carcinoma, squamous cell carcinoma, malignant melanoma, lentigo maligna, dermatofibrosarcoma protuberans, sebaceous carcinoma, microcystic adnexal carcinoma, atypical fibroxanthoma, Merkel cell carcinoma, eccrine carcinoma, extramammary Paget's disease, leiomyosarcoma and primary cutaneous adenocarcinoma); and that meets one or more of the following conditions: - a. a lesion with clinical margins greater than 1.5 cm; - b. a lesion located in an anatomically sensitive area, in particular but not limited to the periocular, perinasal, perilabial, and periauricular surfaces, or the nose; - c. a recurrent malignancy that has not responded to prior therapy; - d. a malignant lesion in a patient with immunodeficiency or genodermatoses predisposing to widespread skin cancers, such as basal cell nevus syndrome; - e. a histologically aggressive lesion (such as a basal cell carcinoma that is sclerosing, infiltrative, baso-squamous, or micronodular, or a squamous cell carcinoma that is poorly differentiated, or demonstrates peri-neural/lymphatic/vascular involvement) at any anatomic site. Closure of the resulting defect by undermining and advancement flaps is included in the fees. More complicated closure may be eligible for payment using skin flap and graft codes.
When to Use
- Use E524 as an add-on to R081 for each additional tissue stage (cut) required to achieve clear margins during Mohs micrographic surgery.
- Apply this code when the initial excision (R081) fails to clear the malignancy, necessitating further horizontal sections to map the tumor extent.
Common Pitfalls
- Billing E524 without an associated R081 on the same claim will result in automatic rejection.
- Claiming E524 when a pathologist performs the histological analysis is prohibited; in such cases, you must bill standard excision codes instead of Mohs-specific codes.
- Attempting to bill E524 for complex repairs (like Z-plasties or full-thickness grafts) is inappropriate, as these require separate skin flap or graft codes.
Billing Tips
- Ensure the number of units for E524 accurately reflects the total number of additional stages beyond the initial R081 excision.
- Document the specific histological findings for each stage to justify the necessity of the additional cuts billed under E524.
Effective: April 1, 2025
M. Integumentary System Surgical Procedures
INTEGUMENTARY SYSTEM SURGICAL PROCEDURES
Surgical
Integumentary System Surgical Procedures
Eligible for payment only to physicians with generally accepted specialized training in Mohs surgery. An example of generally accepted specialized training is the successful completion of a fellowship accredited by the American College of Mohs Surgery.
`R081` and E524 are eligible for payment only to physicians with generally accepted specialized training in Mohs surgery.
Closure of the resulting defect by undermining and advancement flaps is included in the above fees. If more complicated closure is necessary, the service may be eligible for payment using fee codes under skin flaps and grafts.
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