Pathology/Lab Coding Alert

Question: The pathologist examined specimens from a double mastectomy, identifying cancer in both breasts. The pathologist evaluated findings from an automated system to quantify staining of both tumors for ER, PR, Her-2 neu, and Ki57. We reported the service as 88361-26 x 8, but received a rejection. What could be wrong?

Arkansas Subscriber

Answer: If the payer is Medicare or one that follows Medicare rules, you may have run afoul of a Medically Unlikely Edit (MUE) limit. The number of units allowed per day for the service you provided is six.

Based on CPT^® coding principles, you’ve selected the correct code (88361, Morphometric analysis, tumor immunohistochemistry [e.g., Her-2/neu, estrogen receptor/progesterone receptor], quantitative or semiquantitative, per specimen, each single antibody stain procedure; using computer-assisted technology) and the appropriate modifier (26, Professional component) for your pathologist’s interpretation of these quantitative immunohistochemistry (IHC) stains. You’ve also listed the proper number of units, because your pathologist evaluated four separate antibody stain procedures (ER, PR, Her-2 neu, and Ki67) for each of two distinct breast specimens.

Problem: Medicare provides an MUE limit of six for 88361, and you’ve reported eight units. Medicare lists this MUE with “MUE Adjudication Indicator” (MAI) of “3,” which means that it is a date-of-service limit based on a clinical benchmark. Because this isn’t a claim-line edit, you can’t overcome the limitation by listing the services on separate claim lines.

More trouble: Medicare instruction for MAI3 states that if you exceed the clinical benchmark limit for a single date of service (six, in this case), “the contractor will deny all units on the current claim.”

Possible solution: Medicare also instructs that for MAI3 MUEs, “denials may be appealed by the provider,” and the contractor might pay for more units than the MUE limit if you provide adequate documentation of medical necessity.

In your case, if you appeal and provide documentation that your pathologist evaluated two separate specimens, each using a number of IHC stains below the “benchmark” limit of six, you might find that your Medicare contractor will pay for the eight units of 88361.