Mohs under review

By Alexander Miller, MD, June 1, 2020

As Mohs surgical treatment of skin cancers has expanded, enhanced scrutiny of claims by third-party payers has followed. In order to avoid claims adjudication, payment, and/or audit grief, it is essential to fulfill both Mohs surgery qualification requirements as well as billing paradigms. Novitas Solutions, the Medicare Administrative Contractor (MAC) for Jurisdiction H (AR, CO, LA, MS, NM, OK, TX, Indian Health & Veterans Affairs) and Jurisdiction L (D.C., DE, MD, NJ, PA) has recently launched a Targeted Probe and Educate (TPE) audit focused on Mohs surgery. This initiative gives impetus to a review of Mohs qualifying, documentation, and billing criteria.

Medicare spelled out basic Mohs qualifying and documentation requirements in a Medicare Learning Network Matters (MLN Matters) article several years ago (PDF download). The article’s guidance, covered in a prior Cracking the Code on Mohs surgery, lays out national requirements for Mohs surgery that are to be followed by every MAC in the U.S., regardless of whether it has individually published separate guidelines or not. Check out the previous Cracking the Code column on this topic.

Some of the Mohs surgery requirements that must always be met are:

• Mohs surgery may only be done by a physician (MD or DO)

• The Mohs physician must act as both the surgeon (removes the Mohs tissue specimen to be presented to the technician for processing) and pathologist (interprets Mohs microscope slides and maps out any residual tumor sites)

A number of MACs have generated Local Coverage Determinations (LCDs) that further characterize Mohs coverage, indications, and qualifying criteria. These can be found on the individual MAC websites. The Mohs Appropriate Use Criteria (AUC), available for reference via a downloadable app, are variably integrated into the LCDs. Learn more about how to download the app. The logically constructed AUC app facilitates a quick input of sequential clinical criteria to reach an AUC ranking, that can then be integrated into patient recommendations for or against Mohs surgery. One should recognize that the AUC rankings range from “appropriate” to “inappropriate,” and are to be used as components of decision making rather than as absolute validating or negating criteria.

The LCD documents have been modified to exclude coding information, which is now described in a complementary Local Coverage Article (LCA). LCAs specify coding requirements and some special coding circumstances and list pertinent CPT and ICD-10-CM codes. Keep in mind that only the ICD-10-CM codes listed in the LCA document will be considered for Mohs surgery reimbursement.

Now, back to the Novitas TPE initiative. TPEs are authorized for any MAC to institute as a need arises. Although Novitas is the only MAC to have initiated a Mohs TPE audit, other MACs may choose to do the same, and lessons learned from the Novitas project are applicable to all who do Mohs surgery and bill Medicare for it. The Novitas TPE is aimed at significant statistical outlier billing patterns, specifically 59 modifier use in conjunction with Mohs surgery. Audit notifications are mailed to addresses on file with Medicare. Consequently, your staff should be alerted so as to bring appropriate attention to official mailings from Medicare contractors as well as other auditing entities. Failure to reply to a TPE audit may result in penalties, including a referral to Recovery Audit Contractors (RAC), Zone Program Integrity Contractors (ZPIC), United Program Integrity Contractors (UPIC), or demands for retroactive refunds.

Bad news, indeed. If an audit request — which may involve 20 to 40 patient charts — is received, one should ensure that all pertinent information concerning the Mohs surgeries in question is sent, including criteria that satisfy (PDF download) published requirements as well as any requirements in an LCD. If unsure of the requirements, one should explore the MAC website for clarifications. Three rounds of TPE audits may be offered, each followed by one-on-one “education” by a nurse. Once outlier behavior is remedied, then the audits will stop. As the TPE audits focus upon statistical outlier practices, most Mohs surgeons should not expect an audit. However, if you do receive one, take it very seriously: Your financial future may depend upon it.

Example 1

I did a legitimate Mohs surgery on a scalp atypical fibroxanthoma, satisfied all qualification and documentation criteria, submitted a claim to Medicare with CPT 17311 and 17312 for two stages of Mohs surgery, and indexed it to ICD-10-CM code C44.40, “Unspecified malignant neoplasm of skin of scalp and neck,” as there is no ICD-10-CM code specifying an atypical fibroxanthoma. The claim was denied. Why?

Answer: The Mohs LCA in your state does not include C44.40 in its list of “Codes that Support Medical Necessity.” Typically, “unspecified” neoplasm ICD-10-CM codes do not qualify for payer reimbursement. One should use an “Other specified malignant neoplasm” code, in this case, C44.49, “Other specified malignant neoplasm of skin of scalp and neck.”

Example 2

You do two Mohs surgeries on a patient. One is for a basal cell carcinoma on the nose and another, for a basal cell carcinoma on the right cheek. Each tumor clears with one stage of Mohs. You submit a claim with CPT 17311 for the nose Mohs and 17311-59 for the cheek Mohs. A nose flap repair is coded with CPT 14060 and a cheek flap repair is reported with 14040-59.

Answer: Correct. The 59 modifier distinguishes the two separate Mohs procedures and separate adjacent tissue rearrangement procedures as distinct. The 59 modifier is to be applied to only one set of the two sets of procedures.

Example 3

You do two Mohs surgeries, one with two stages on the right cheek, and the other with two stages on the left temple. Both sites are repaired with adjacent tissue rearrangement. You report: 17311-59, 17312-59, 14040-59 for the cheek surgery and 17311-59, 14040-59 for the temple Mohs excision and repair.

Answer: Incorrect. Too many modifiers! Consistent indiscriminate application of the 59 modifier may get you audited! The primary Mohs procedure and reconstruction, in this case the cheek, should have no modifier appended: 17311, 17312, 14060. The second Mohs procedure is done on an identical anatomical billing area, reported with ICD-10 C44.319 for both the cheek and temple. Furthermore, the reconstruction involves a repeat of the same CPT code, 14040. Without an appropriate modifier placement, one or both of the Mohs surgery claims may be rejected, or if paid, may be retroactively rejected and subject to a refund. Not good! The 76 modifier, “Repeat procedure or service” should be appended to the second Mohs procedure and reconstruction as: 17311-76 and 14040-76. In some instances, reporting 17311-59,76 and 14040-59,76 may work best. However, it is essential that only one set of codes receives modifiers.

Example 4

You punch biopsy a lesion suspicious for a morpheaform basal cell carcinoma on the temple, have your technician generate diagnostic frozen section slides, confirm the tumor presence, and proceed to excise it with two stages of Mohs surgery. You report CPT 11104-59 and 88331-59 for the biopsy and diagnostic frozen section and 17311, 17312 for the Mohs surgery.

Answer: Correct. Diagnostic biopsy and frozen section procedures are covered only under select circumstances (see LCD criteria). Only the biopsy and diagnostic frozen section CPT codes should be appended with a 59 modifier. The 59 modifier should not be appended to the Mohs procedure.

Example 5

You do a five-stage Mohs excision on one day before the patient indicates they cannot tolerate further surgery. You then continue the Mohs surgery the following day, clearing the excision margins with a total of seven stages of Mohs surgery. You document the reason for discontinuation as related to patient request in the medical record. You report the first five stages with CPT 17311, 17312x4 and the subsequent day’s two stages with CPT 17311-79, 17312-79.

Answer: Incorrect. The subsequent day’s continuation of two stages of Mohs surgery was correctly coded with the primary Mohs code, 17311, and then 17312, per Mohs MLN guidelines. However, the 79 modifier should not have been appended, as it is indicated only when additional unrelated procedures are done within a postoperative period. Mohs surgery has a zero-day global postoperative period. Neither 79 nor 58 (staged or related procedure during the postoperative period) are necessary.

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