Depends on carrier's preference.
Some carriers will allow 76 on the additional units above the MUE. Some will accept 59.
I would also make sure you populate Box 19 (Narrative) with a statement like "A total of 4 CPT 88342 performed on 03/03/2018
Make sure your appeal cover letter is clear and note show medical necessity of performing more than 3 IHC stains and they each stain was a unique stain.
MUE guidance and policies appear in the National Correct Coding Initiative policy files.
We find the following instructions:
In the April 1, 2013 version of MUEs, CMS began introducing date of service (DOS) MUEs. Over time CMS will convert many, but not all, MUEs to DOS MUEs. Since April 1, 2013, MUEs are adjudicated either as claim line edits or DOS edits. If the MUE is adjudicated as a claim line edit, the units of service (UOS) on each claim line are compared to the MUE value for the HCPCS/CPT code on that claim line. If the UOS exceed the MUE value, all UOS on that claim line are denied. If the MUE is adjudicated as a DOS MUE, all UOS on each claim line for the same date of service for the same HCPCS/CPT code are summed, and the sum is compared to the MUE value. If the summed UOS exceed the MUE value, all UOS for the HCPCS/CPT code for that date of service are denied. Denials due to claim line MUEs or DOS MUEs may be appealed to the local claims processing contractor. DOS MUEs are utilized for HCPCS/CPT codes where it would be extremely unlikely that more UOS than the MUE value would ever be performed on the same date of service for the same patient.
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If a HCPCS/CPT code has an MUE that is adjudicated as a claim line edit, appropriate use of CPT modifiers (e.g., 59, 76, 77, 91, anatomic) may be used to report the same HCPCS/CPT code on separate lines of a claim. Each line of the claim with that HCPCS/CPT code will be separately adjudicated against the MUE value for that HCPCS/CPT code. Claims processing contractors have rules limiting use of these modifiers with some HCPCS/CPT codes.