Surgical coding challenges
Cracking the code
Dr. Miller, who is in private practice in Yorba Linda, California, represents the American Academy of Dermatology on the AMA-CPT Advisory Committee.
By Alexander Miller, MD, March 1, 2020
There are instances where we do multiple surgical and/or diagnostic procedures on a patient during one encounter. This may be done for medical indications as well as for patient convenience, as it compacts several services into one encounter and reduces the need for multiple separate visits — a particularly valuable benefit for patients who may travel a substantial distance to obtain care. However, such patient benefits may come at a cost for dermatologists who fail to appropriately report their services.
Multiple procedures performed during the same encounter should be reported with a modifier or modifiers to distinguish the separate services. Typically, this would require appending a 59 modifier (or XE, XS, XP, or XU — check with individual payers to confirm that they accept the use of the X[ESPU] modifiers) to the additional procedures in order to distinguish them from each other. Occasionally, a 76 modifier would be required. Read more of the Academy's resources on modifiers. Then, there is the matter of whether the separate services would be reimbursable at all, and under what circumstances.
For example, if during the course of Mohs surgery, you clear the margins histologically but then submit an additional peripheral margin for formalin fixed sections. How would you report this, and would this additional service be reimbursable? How would a “debulking” of central tissue prior to Mohs excision be reported if it is sent for histopathologic evaluation?
The AMA CPT Assistant, February 2014, page 10 states the following: “there are legitimate instances in which tissue separate from the tissue examined during the Mohs surgery is submitted for subsequent formalin-fixed processing and histopathologic examination. In these instances, the submitted specimen may originate from the same operative site or from a different operative site but is not the same tissue that was processed during the Mohs surgery. In such a situation, codes 88302-88309, describing the pathology performed on the separate tissue, may be reported in addition to the Mohs surgery codes (17311-17315).”
Medicare Administrative Contractors parallel the CPT Assistant in their Local Coverage articles and policy, stipulating that the submitted tissue must be different from that processed during the Mohs surgery, such as an additional tissue margin not evaluated with Mohs surgery.
If an additional tissue margin excision is done during the same day as the Mohs surgery and submitted for separate formalin-fixed histopathologic evaluation, then it would be challenging to obtain reimbursement for the excision. The Mohs surgery codes include tissue excision, so coding for an excision done on the same site as Mohs surgery would risk having the Mohs surgery disallowed and the excision only paid. That would be most aggravating, as one would have to appeal the rejected service.
However, if the additional margin excision were done on a subsequent date/encounter, then the service would be reportable and possibly covered by an insurer. Such a procedure would represent a staged excision, and would be reported as follows:
The original tumor’s ICD-10 diagnostic code
Appropriate CPT code based upon the tumor location and the diameter of the additionally excised margin of tissue
No modifier needed, as Mohs surgery is a zero-day global period service
The medical record should in all cases specify why it was necessary to remove additional tissue and send it for histopathologic evaluation
A histopathology CPT code 88305 charge billed as date of service same as the Mohs surgery may lead to a disallowance of the Mohs surgery payment. Be prepared to appeal such an impropriety and ensure that your chart records justify the charge.
How about a Mohs tissue debulking specimen sent for histopathologic evaluation? How would this be reported? First, debulking of Mohs excised tissue is included in the CPT Mohs surgery descriptor, which states, “Mohs micrographic technique, including removal of all gross tumor.” So, no separate reporting of this tissue removal.
However, the histopathologic processing and interpretation would be separately reportable with CPT code 88305. The medical record should justify why it was necessary to evaluate debulked tissue with formalin fixed sections. Beware of routinely sending debulked tissue for histopathology, as repeated reporting of CPT code 88305 in association with Mohs surgery creates a pattern and would mark your practice as a statistical outlier, attracting an audit by the insurer or outright rejections of the Mohs surgery portions of claims. An audit could disallow both current and previous Mohs surgeries, leading to a demand for a refund. Ouch!
Example 1: You are referred a Medicare patient for Mohs surgery of a presumed basal cell carcinoma on the nose. No prior biopsy report is available, and the patient is unsure of when the site had been biopsied. You proceed to do a diagnostic frozen section punch biopsy of the site, confirm the presence of a morpheaform basal cell carcinoma, and do the Mohs surgery. You report the biopsy with CPT code 11104-59 and the diagnostic frozen section processing and interpretation as 88331-59.
Answer: Correct. Medicare Administrative Contractors instruct that modifier 59 be appended to the biopsy code in this scenario. Additionally, the medical record should delineate that either results of a biopsy done within the preceding 60 days were not obtainable after a “reasonable effort” to procure them, or that a biopsy had not been done in the preceding 60 days.
Example 2: After debulking central tumor tissue during the course of Mohs surgery you have your Mohs technician prepare frozen section slides of the debulked tissue and interpret them in order to further characterize the tumor, which was biopsied 10 days prior and reported as a squamous cell carcinoma. You submit CPT code 88331-59 for your frozen section interpretation.
Answer: Incorrect. Frozen section specimen interpretation in this case is not separately reportable, as a biopsy had been done only 10 days prior to the Mohs surgery, and its results were available. Reporting a frozen section examination in such a scenario could negate the Mohs surgery, leading to non-payment by the insurer.
Example 3: You identify a potential infiltrating basal cell carcinoma on the left cheek, which you punch biopsy on the same day as you do a two-stage Mohs surgery on a right cheek tumor. You report the Mohs surgery with CPT codes 17311 and 17312, and the biopsy as 11104-59.
Answer: Correct. Although the above coding is correct, one should clearly document that the two lesions were on opposite sides of the face. This distinction may also be specified in the notes section of the CMS1500 billing form. Appending an additional modifier, -LT for the left cheek and -RT for the right cheek, may or may not help with reimbursement, as this would depend upon the insurer’s ability to properly process laterality modifiers. A rejected claim may have to be appealed.
Example 4: The third stage of a Mohs excision of a forehead squamous cell carcinoma reveals no residual squamous cell carcinoma but an unexpected infiltrating basal cell carcinoma at a lateral margin. You proceed to excise the newly diagnosed basal cell carcinoma with two additional stages of Mohs surgery. You report the service as CPT codes 17311 and 17312x2 for the squamous cell carcinoma excision and 17311-59 and 17312-59 for the basal cell carcinoma removal.
Answer: Incorrect. Although a new tumor was identified during the course of Mohs surgery, its site was contiguous with an ongoing Mohs surgical excision. The CPT describes Mohs surgery as “a technique for the removal of complex or ill-defined skin cancer.” The Mohs procedure codes are not tumor specific. Consequently, since the two tumors led to an excision of additional contiguous Mohs layers, proper reporting should be: CPT codes 17311, 17312x4 (two units for the squamous cell carcinoma excision and two additional units for the excision of the merged basal cell carcinoma).
