CMS institutes changes to IHC coding

As of Jan. 1, 2014, Centers for Medicare and Medicaid Services (CMS) has deemed CPT codes 88342 and 88343 “not valid for Medicare purposes" when billing for qualitative immunohistochemistry (IHC) and will deny payment if billed on a claim.

Instead, Medicare has created codes G0461 and G0462 specifically for their use. To report a professional, technical or global charge for qualitative IHC testing for a Medicare beneficiary on and after Jan.1, 2014, you must use the appropriate HCPCS Level II code with the appropriate modifier where applicable:

  • G0461 Immunohistochemistry or immunocytochemistry, per specimen; first single or multiplex antibody stain;
  • +G0462  each additional single or multiplex antibody stain (List separately in addition to code for primary procedure)

Currently, CMS pays for just one unit of service for IHC cocktail stains. With the new directive, CMS is now indicating that IHC should be billed based on the primary stain, not on the basis of the number of individual antibodies that can be detected and analyzed using that stain. For example, Medicare can be billed for one unit of G0461 for a PIN-4 IHC cocktail applied to one prostate biopsy specimen, even though the report may give a result for each of the three separately interpretable antibodies that make up the primary cocktail stain (one vial).

According to the current work descriptor, one unit of G0461 can be billed for the first qualitative IHC stain for a given tissue specimen. If you perform one qualitative IHC stain on a specimen which then results into two, three or more additional qualitative IHC stains from that specimen, each such additional stain will be reported as one unit of G0462.

For example, if a single skin biopsy is worked up using HMB-45, tyrosinase and Melan-A qualitative IHC stains (three separate vials), you'd report that as one unit of G0461 (first stain) and two units of G0462 (two additional stains).

Note: Codes G0641 indicates that it is intended for use "per specimen; first single OR multiplex stain".

On the other hand, with non-Medicare patients, pending any restrictions from specific payors, providers should continue using 88342 and the new add-on code 88343.           

  • 88342 Immunohistochemistry or immunocytochemistry, each separately identifiable antibody per block, cytologic preparation, or hematologic smear; first separately identifiable antibody per slide.
  • +88343 each additional separately identifiable antibody per slide
    (List separately in addition to code for primary procedure)

Note: The 88342 code descriptor now states "per block" which is a change from "per specimen." Also note "per slide" in reference to cocktails or multiplex IHC stains. Thus, for non-Medicare patients, the only time one can use 88343 is with cocktails.

For services rendered on after the effective date, instead of reporting “88342 X 3” for one block, one will now report “88342, 88343 X 2”.

Providers are reminded to note that the reporting sequencing of per specimen – rather than per block – applies to Medicare, Tricare and Medicaid. Currently, Tricare and Medicaid agencies typically do not use HCPCS Level II codes. However, CMS has not yet provided guidance on whether one should use 88342 and 88343 or the G-codes with Tricare and Medicaid claims. The American Academy of Dermatology and other affected societies have submitted an inquiry for further clarification to CMS and will share the response and outcome as soon as it is received. Providers are encouraged to reach out directly to commercial payers to ascertain specific coding guidance that apply to each payer.

2014 AMA CPT Changes - Insider's View

Immunohistochemistry code 88342 has been revised to more clearly define the unit of service. Prior to 2014, 88342 described Immunohistochemistry including tissue immunoperodixase, each antibody. In 2014, the code descriptor now includes immunocytochemistry and describes each separately identifiable antibody per block, cytologic preparation, or hematologic smear. The unit of service is the first separately identifiable antibody per slide. An add-on code (88343) has been added to identify each additional separately identifiable antibody per slide. When more than one antibody is applied to the same slide, one unit of 88342 should be reported and one unit of 88343 for each additional antibody. A new parenthetical note following code 88343 provides this instruction. The cross-reference parenthetical notes following codes 88313 and 88319 have been revised to include 88343.

There are also some changes implemented to prostate biopsy coding:

CMS established new G codes (G0416-G0419) which will apply to all prostate biopsies (regardless of surgical technique) when 10 or morespecimens are reviewed. “Increased scrutiny in the reporting of multiple prostate biopsy specimens led to this policy change,” says CMS.

Prostate biopsies with fewer than 10 specimens should be billed using CPT code 88305.

For examples on billing for qualitative IHC stains, see the Question and Answer section.

More information on billing for qualitative IHC stains can be found at