Unit of Service Changes for IHC Codes 88342, 88360 and 88361

July 13, 2012

As you are probably aware, there has been a significant change in the unit of service coding rules for IHC codes 88342, 88360 and 88361. Effective January 1, 2012, per the AMA and CAP, the unit of service for each IHC stain charge is one unit per different antigen tested and individually reported, per specimen. This policy reverts back to the College’s position in CAP Today, June 2004, and the American Medical Association’s CPT Assistant, dated October 2010.

The following is an example of this new coding rule:

Example: A sentinel lymph node is submitted for pathologic review and diagnosis. The node is processed and 3 blocks are submitted (A1 – A3) for review. A pancytokeratin stain is done on blocks A1 and A2. This case should be coded 88342x1.

In a sharp contrast to the AMA and CAP’s policies, CMS has revised its coding policy by instituting an NCCI edit, effective January 1, 2012. CMS has indicated in their policy manual that pathologists should not report more than one unit of IHC service, per specimen for an immunohistochemistry antibody stain, even if it contains multiple separately interpretable antibodies. Therefore, CMS clarifies that IHC stains that are made up of multiple antibodies (ie. double stain, triple stain or cocktail stains) should not be reported more than one time, or one unit of service, per specimen for each immunohistochemical antibody stain procedures. Therefore, there will be different coding and billing policies in place for IHC whether it’s a Medicare account or a commercially covered patient. Given these two new policies, following are several IHC combinations and the corrected coding to be followed.

1. PIN4 IHC Cocktail Stain – 3 individual antibodies, each distinguishable one from another by color is applied to a single prostate biopsy specimen. Per the AMA and CAP, report 88342x3. Per Medicare/Medicaid, report 88342x1.

2. Double Stain – 1 primary antibody HMW cytokeratin and 1 primary antibody P504S. One stains brown, the other red. Both applied to the same specimen. Per the AMA and CAP, report 88342x2. Per Medicare/Medicaid, report 88342x2.

3. Triple Stain – 1 primary antibody for p63, 1 primary antibody stain for CK5 and 1 primary cocktail stain TTF‐1 and napsin A (TTF‐1 and napsin A each stain a different color). Per AMA and CAP, report 88342x4. Per Medicare/Medicaid, report 88342x3.

4. URO‐3 – 1 primary antibody for CK20 and 1 cocktail stain for CD44 and p53. Each is separately distinguishable by color. Per AMA and CAP, report 88342x3. Per Medicare/Medicaid, report 88342x2.

Note, when coding for this service, APS is asking that all clients continue to report all immunohistochemical stains per antibody, per specimen, as carrier information will probably not beknown at the time the case is coded. APS Medical Billing has programmed pre‐billing edits in its system to review and handle all coding adjustments, per financial class. Initially, this edit will only be applied to Medicare and Medicaid accounts. If other carriers decide to follow this coding policy, updates will be provided. In addition, the number of glass slides that are used during any IHC procedure isn’t relevant to the unit of service assignment decision. Hopefully, this further clarifies this unit of service coding change for IHC stain. Should you have any further questions, please feel free to contact Jan Toczynski or Holly Wolford in our Coding department, or Tom Scheanwald.