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Billing Frozen Sections (88331) on the same day as Mohs
Last Updated: 07/19/2016
There are two scenarios where it is permissible to bill 88331 (pathology consultation during surgery with frozen section) on the same day as Mohs Micrographic Surgery.
1. A provider wants to confirm a suspicious lesion is malignant, a skin specimen is obtained (e.g., biopsy), frozen section is performed, and this result leads to the decision to perform Mohs surgery on the patient that day. This is a confirmation biopsy prior to Mohs.

2. A skin specimen is obtained for tissue completely unrelated and separate from the lesion on which Mohs is performed that doesn’t involve Mohs surgery.

The role of the National Correct Coding Initiative in the above scenarios
The National Correct Coding Initiative (NCCI) edits list CPT code pairs that CMS considers to be bundled together (or mutually exclusive) and cannot be billed together on the same date of service. The guidelines and coding rules for the NCCI can be found on the CMS website…

There is a helpful document from CMS that explains the concept and rules of the NCCI in coding claims.

CMS specifically states…

“NCCI Procedure-to-Procedure (PTP) code pair edits are automated prepayment edits that prevent improper payment when certain codes are submitted together for Part B-covered services.”

However, we know that there are instances where certain code pairs should be billed together on the same date of service, if certain clinical circumstances or criteria are met. The biller would add a modifier (such as Modifier 59 or XS) to over-ride the NCCI edits and indicate to the carrier that the clinical circumstances have been met and warrant separate payment.

CMS specifically states...

“Modifiers may be appended to HCPCS/CPT codes only if the clinical circumstances justify the use of the modifier. A modifier should not be appended to a HCPCS/CPT code solely to bypass a PTP code pair edit if the clinical circumstances do not justify its use. If the Medicare Program imposes restrictions on the use of a modifier, the modifier may only be used to bypass a PTP code pair edit if the Medicare restrictions are fulfilled.”

Next, let’s look at each of the previous scenarios in a bit more detail.

Scenario 1 – Confirmation biopsy (or path consultation prior to Mohs)

A patient is in the office presenting with a lesion that is of concern to the provider. The provider makes the decision to do a simple biopsy and frozen section utilizing the in-house lab to determine if the lesion meets the criteria for performing Mohs surgery. The frozen section pathology report shows a malignant lesion with aggressive margins (or other concerning morphology) and the results are discussed with the patient. The provider makes the decision to perform Mohs during the same operative session. In this case, the biopsy/frozen section can be billed in addition to Mohs.

This scenario is addressed specifically in the National Correct Coding Initiative Edits.

Specifically in the link… NCCI Policy Manual for Medicare Services - Effective January 1, 2016

Within this file are several documents. Of importance is the file called CHAP3-CPTcodes10000-19999_final103115.pdf

This PDF document discusses the NCCI as it related to the Integumentary System guidelines for CPT codes 10000-19999

On page III-8 we see the following excerpt. I have bolded the most important instruction.
“F. Mohs Micrographic Surgery

Mohs micrographic surgery (CPT codes 17311-17315) is performed to remove complex or ill-defined cutaneous malignancy. A single physician performs both the surgery and pathologic examination of the specimen(s). The Mohs micrographic surgery CPT codes include skin biopsy and excision services (CPT codes 11100-11101, 11600-11646, and 17260-17286) and pathology services (88300-88309, 88329-88332). Reporting these latter codes in addition to the Mohs micrographic surgery CPT codes is inappropriate. However, if a suspected skin cancer is biopsied for pathologic diagnosis prior to proceeding to Mohs micrographic surgery, the biopsy (e.g., CPT codes 11100-11101) and frozen section pathology (CPT code 88331) may be reported separately utilizing modifier 59 or 58 to distinguish the diagnostic biopsy from the definitive Mohs surgery. Although the CPT Manual indicates that modifier 59 should be utilized, it is also acceptable to utilize modifier 58 to indicate that the diagnostic skin biopsy and Mohs micrographic surgery were staged or planned procedures. Repairs, grafts, and flaps are separately reportable with the Mohs micrographic surgery CPT codes.”

Clearly, CMS is stating that it’s permissible to bill 88331 (after a biopsy) on the same date of service as Mohs Micrographic surgery, as long as that biopsy/frozen section leads to the decision to perform Mohs that day.

Since the separate payment criteria have been met, and codes 88331 and 11100 are bundled with 17311 according to the NCCI edits, you would bill using modifier 59 to over-ride the payment edit bundle. Modifier 58 (staged or planned procedure) is also permissible. Remember that modifier 59 is used as a modifier of last resort if no other more descriptive modifier is available.

For example, you might bill:

17312 (if applicable)
14060 (or other applicable repair code)
11100 -58 (staged or planned procedure)
88331 -58 (staged or planned procedure)


17312 (if applicable)
14060 (or other applicable repair code)
11100 -59 (distinct procedure or service)
88331 -59 (distinct procedure or service)

Any other frozen sections performed as part of Mohs Micrographic surgery on a specific lesion or piece of tissue cannot be billed separately. These are simply billed as additional stages or blocks using an appropriate Mohs code.

Caveat: It is recommended that the medical exam documentation and operative report clearly indicate the lesion was suspicious, a confirmation biopsy and frozen section were performed to validate the medical necessity of performing Mohs, and that the results were discussed with the patient prior to Mohs being performed. It is also highly recommended that a formal pathology report from the frozen section be permanently documented in the patient’s medical record. Remember documentation is your best weapon in an audit or appeal.

We have received reports of some providers being audited for frozen sections and Mohs. Since no documentation was in the record indicating that the confirmation biopsy was done to show the medical necessity for meeting Mohs criteria and that the results were shared and discussed with the patient prior to Mohs, the audit denied the 88331 with Mohs. Denials have also occurred and audits have been lost for lack of a formal path report for the frozen section prior to Mohs.

Caution: Many EMRs have default wording populated in the chart note whenever a biopsy is performed stating that the path results will be shared with the patient in X days after path is returned. This is not the case with frozen sections being performed prior to Mohs. Do not rely upon technology to perform documentation for you automatically. As a provider, you are ultimately responsible for the accuracy and completeness of your documentation for each and every patient and for each unique circumstance. Note cloning and standardized phraseology can work against you in an audit.

Scenario 2 – Frozen section on separate and unrelated lesion

Another scenario might be when a patient is referred to a Mohs surgeon for treatment of a malignant lesion, such as BCC. When the patient is in the office, the provider notices a second unrelated lesion of concern and performs a frozen section to rule out malignancy. This second unrelated lesion turns out to be benign, (such as an AK), and therefor does not meet the criteria for Mohs.

In this case, you have a separate and unrelated lesion on which a biopsy and frozen section were performed.

17312 (if applicable)
14060 (or other applicable repair code)
11100 -59 (distinct procedure or service)
88331 -59 (distinct procedure or service)

ote: As of 2015, the new ‘X’ modifiers have been put in place and are accepted by Medicare and most commercial carriers. Although nearly all carriers still accept modifier 59, if used correctly, you could also code the above example as the following.

17312 (if applicable)
14060 (or other applicable repair code)
11100 -XS (separate organ/structure)
88331 -XS (separate organ/structure)

88304/88305 and Mohs

As of 7/1/2016, the NCCI edits now list Mohs codes 17312-17315 with pathology codes 88304 and 88305 as a series of bundled code pairs. The same considerations above regarding about Mohs and frozen being performed on the same date of service would apply to traditional pathology.

Processing of unrelated specimens or tissue outside that of the tissue examined by Mohs technique would be permissible as a clinical circumstance where 88304/88305 might be performed and billed separately.

We see the above concepts described in several of the Medicare contractor’s Local Coverage Determination (LCD) policies.

For example Novitas Solutions’ LCD L34961

We see within this document…
“There are occasional clinical situations in which tissue separate from the tissue examined during Mohs surgery is appropriately submitted for subsequent formalin fixed processing and histopathologic examination. The submitted tissue is not the same tissue that was processed during the Mohs surgery. It may constitute a tissue margin beyond that evaluated with Mohs surgery or it may involve a totally unrelated tissue specimen. In such situations, both the Mohs surgery and the histopathology may be considered reasonable and necessary. In such cases, the clinical record must clearly show the reasoning for the histopathologic specimen and interpretation. Occasionally, that biopsy may need to be done on the same day that MMS is planned to be done.”

Medicare versus Commercial

The above information is for Medicare. Many commercial carriers follow similar guidelines as far as the NCCI edits are concerned. This is especially true if it is a Medicare Advantage plan administered by a commercial carrier. In this case, the commercial carriers are required to follow the Medicare guidelines such as the National Correct Coding Initiative.

Providers should verify with commercial carriers and contracts to see their documentation and coverage requirements for billing frozen sections on the same day of service as Mohs.

Second opinions or confirmatory pathology

Mohs surgeons cannot bill carriers for tissue specimens on which Mohs was already performed for purposes of a second opinion or confirmatory pathology. The role of the Mohs surgeon is to act as both the surgeon and pathologist. A Mohs surgeon can seek the opinion of a second pathologist, but it will not be reimbursed by carriers in most instances.

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