This commentary is a summary prepared by McKesson’s Business Performance Services division and highlights certain changes, not all changes, in 2013 CPT® codes relating to the specialty of pathology. This commentary does not supplant the American Medical Association’s current listing of CPT® codes, its documentation in the annual CPT Changes publications, and other related publications from American Medical Association, which are the authoritative source for information about CPT® codes. Please refer to your 2013 CPT® Code Book, annual CPT® Changes publication, HCPCS Book and Payer Bulletins for additional information, including additions, deletions, changes and interpretations that may not be reflected in this document.

CPT is a registered trademark of the American Medical Association (“AMA”). The AMA is the owner of all copyright, trademark and other rights to CPT® and its updates.

Distinguishing between Immunohistochemistry Codes

It’s important to be able to distinguish between the three immunohistochemistry (IHC) codes: 88342, 88360 and 88361. There are basically two components to determine when applying the IHC codes. First, how the results are reported (qualitative, semi-quantitative/quantitative) and second, the method used to perform the reporting of results (manual or automated).

Reporting Results

Qualitative Reporting

Code 88342 applies when a pathologist reports an IHC stain using qualitative expression. A result is stated in qualitative terms if the report says simply that a stain is positive or negative. In the example, “the tissue stain was negative for cytokeratin,” a value of 1+, 2+, etc., reported with NO scale is also considered qualitative (i.e., scale example: 1+ = 10% cells stained).

Semi-quantitative and Quantitative Reporting

Codes 88360 and 88361 apply when a quantitative or semi-quantitative result is determined and reported using the IHC staining technique by manual (88360) or computer-assisted (88361) methods.

  • Semi-quantitative results are derived by counting the number of positive cells on the slide and expressing the outcome as a percent of total cells. A common method of “scoring” IHC involves counting positive cells to a threshold number such as 10%, combined with a subjective assessment of staining intensity: the 0 to 4+ score is deemed to be a semi-quantitative result. {CAP Today, Feb. 2005}.

    Please note that the report should contain both the threshold (scale) percentage value and the score value (0-4+) in order to be considered semi-quantitative. A mere report of 1+, 2+, etc. is not sufficient to meet semi-quantitative values and must be billed as qualitative (88342 for IHC).
  • Quantitative results are those expressed in numerical value (0, 5, 10, etc.) – actual numerical counts.

Method Used to Report Results

Quantitative or semi-quantitative immunohistochemistry using computer-assisted technology (digital cellular imaging) should be reported as CPT code 88361. CPT code 88361 should not be used to report any service other than quantitative or semi-quantitative immunohistochemistry using computer-assisted technology (digital cellular imaging). Digital cellular imaging includes computer software analysis of stained microscopic slides. Documentation must state it is computer assisted in some form or fashion (i.e., imaging, digital analysis).

Quantitative or semi-quantitative immunohistochemistry performed by manual techniques should be reported as CPT code 88360.

Unit of Service Requirements

The unit of service for IHC stains (88342, 88360 or 88361) is per each different antigen tested and individually reported per different specimen as stated in CAP Today, June 2004 and CPT Assistant, AMA, Oct. 2010. The unit of service is not based on the number of blocks or slides that have the same antibody stained and interpreted. This standard applies to all payers (Medicare, Medicaid and Commercial).

Cocktail Stains

However, what about “cocktail” stains? Cocktail stains are those which contain multiple different antibodies within the same stain vial used in a single staining procedure.

For Medicare contractors, you cannot report multiple units of 88342/88360/88361 (Immunohistochemistry [including tissue immunoperoxidase], each antibody) for “cocktail” stains containing multiple antibodies in a single “vial” applied in a single procedure, even if you document that each antibody provides distinct diagnostic information.

Medicare’s National Correct Coding Initiative Policy Manual states: “Physicians should not report more than one unit of service per specimen for an immunohistochemical antibody(s) stain (procedure) even if it contains multiple separately interpretable antibodies.”

An example is the PIN-4 stain, where the stain contains three different antibodies that stain different colors within that one single staining procedure. Even though the pathologist may interpret three antibodies, Medicare deems this as one unit of service. For private insurers that do NOT follow Medicare coding guidelines, the AMA and the CAP (CAP Today, June 2004) state that when an antibody is uniquely identifiable and reported via IHC technique, it’s separately chargeable, regardless of the staining platform (i.e., single stain/single antibody vs. cocktail stain vs. double- or triple-stain).

CPT 2013
CAP Today, June 2004


Kimberly J. West, CPC
National Pathology Auditing & Coding Manager
McKesson Business Performance Services


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