Changes in IHC coding in 2014

Two sets of IHC coding will be implemented in 2014.  The American Medical Association (AMA) and the Centers for Medicare and Medicaid Services (CMS) could not come to a mutually accepted compromise.These coding authorities have different approaches to
the units of service in health care practice.

The diagrams below present both coding provisions separately. The comments are taken from official materials such as the AMA’s CPT-2014 Codebook (diagram 1) and CMS Physician Fee Schedule (diagram 2) final rule on November 27, 2013.

Diagram 1



Diagram 2


 (Emphasis added by bold). There are three main differences:

AMA’ CPT-2014 suggested 88342 each separately identifiable antibody per block/cytology/smear and 88343 for each additional separately identifiable antibody per slide.

CMS abandoned CPT for Medicare claim filing for qualitativeimmunohistochemistry suggesting two G codes, namely G0461 for immunohistochemistry or immunocytochemistry per specimenand G0462 for each additional single or multiple stain.

G0462 code requires  List separately in addition to code for primary procedure. This requirement shown in parentheses is the key for cuts in reimbursements.

The governmental organizations (Medicare, Medicaid, and Tricare) must follow CMS provisions. Private insurers can use AMA’s coding, but it seems that eventually they will follow CMS. The CMS’s approach is more consistent with the CPT coding principles of the orientation on the specimen as a unit of service, rather than the block/slide.

The nuanced approach to changes in IHC coding starting on January 1st, 2014 is presented in an excerpt from Dennis Padget’s Pathology Service Coding Handbook, Subscriber Special Bulletin, December 16, 2013, posted on HistoNet discussion group website on 12/18/13.

The main changes are, however, in the CMS’s reimbursement rates. This website touches on these issues as little as possible. Some data are presented in the article Add-on CPT Coding. See also the post 88343 vs. G0462 on “Grossing Technology in Surgical Pathology” (

Unfortunately for 2015, the confusion that is feeding numerous interpretations and consultants remains: For non-Medicare it is per block – CPT code 88342.
For Medicare – per specimen. G0461 for the first antibody and G0462 for each additional different antibody.

And of course, 88343 for multiple stains on the same slide, when the first is 88342 and additional 88343, for example in prostate triple stain (PIN4 cocktail).



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