Pathology/Lab Coding Alert

Distinguish rules for 88342, +88343.

The CPT® 2014 promise of billing immunohistochemistry (IHC) stains per block was too good to be true — at least for Medicare.

Instead of accepting revised and new CPT® 2014 codes 88342 (Immunohistochemistry or immunocytochemistry, each separately identifiable antibody per block, cytologic preparation, or hematologic smear; first separately identifiable antibody per slide) and +88343 (…each additional separately identifiable antibody per slide [List separately in addition to code for primary procedure]), Medicare implemented the following two codes on Jan. 1:

• 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).
  

That means you have to consider two code sets for reporting qualitative IHC based on whether the payer is Medicare or not. Let our experts help you learn differences in how you’ll use the codes — and how you’ll get paid.

Difference 1: Unit of Service

The first difference you’ll notice between the two code sets is that you should report 88342-88343 “per block,” but G0461-G0462 “per specimen.”

“That distinction will be significant for specimens such as breast, that often require processing more than one tissue block per specimen,” explains R.M. Stainton Jr., MD, president of Doctors’ Anatomic Pathology Services in Jonesboro, Ark.

Tip: The block/specimen unit of service distinction also poses a dilemma for coding qualitative versus quantitative IHC. Read “88360-88361Use ‘Specimen’ as Unit of Service” in this issue to learn more.

See antibody distinction: The next disparity you’ll notice is that you should report 88342-+88343 “per separately identifiable antibody,” but G0461-G0462 “per single or multiplex antibody stain.”

This distinction means that you should use 88342/+88343 to separately bill for distinct antibodies in a “cocktail” stain, but you cannot use G0461-G0462 to do so. The ‘G’ codes count multiplex (cocktail) stains as a single unit.

“Reference to ‘multiplex stain’ leaves no room for ambiguity; one primary stain, whether it targets a single antibody or multiple antibodies, warrants just one unit of charge,” explains Dennis Padget, MBA, CPA, FHFMA, The Villages, Fla., Senior Editor in Chief, Pathology Service Coding Handbook, for American Pathology Foundation.

Difference 2: How to Use the ‘Child’ Code

Codes 88342/+88343 and G0461/G0462 each represent a set of two codes, with a “parent” code followed by an indented “child” code sharing the same initial definition preceding the semicolon. But that’s where the similarity ends. The two pairs of codes do not have parallel usage.

CPT® codes: You should use 88342 for each distinct antibody stain on a tissue block. That means you’ll report multiple units of 88342 if the pathologist examines multiple distinct antibody stains on different slides. Don’t turn to +88343 unless you’re dealing with a cocktail stain. Then you’ll use +88343 only for the second and subsequent antibodies in a cocktail stain that involves multiple separately identifiable antibodies applied to a single slide and distinctly evaluated by the pathologist (see “88342, +88343 Clarify Immuno-Stain Coding” in Pathology/Lab Coding Alert Vol. 14 No. 12 for a complete discussion of how to use these codes).

HCPCS Level II codes: You should use G0461 for the first distinct antibody or multiplex (cocktail) stain on a tissue specimen. Then you’ll use G0462 for each additional distinct or multiplex antibody stain.

Example: The pathologist examines distinct qualitative estrogen receptor (ER) and progesterone receptor (PR) stains for breast tissue specimen (single block). You should code this scenario as 88342 x 2 for non-Medicare payers and G0461 plus G0462 for Medicare.

Difference 3: What You’ll Get Paid

Although 88342/88343 aren’t parallel in usage, they are in pay. CMS crosswalked G0461 payment to 88342 relative value units (RVUs), and G0462 payment to 88343 RVUs. That means you’ll stand to lose money three ways when reporting qualitative IHC to Medicare. The following three examples (each assuming you’re entitled to bill the global service) illustrate the three variables that will affect your bottom line:

1. Per block vs. per specimen example: Sentinel lymph node specimen with cytokeratin stain, two blocks:

a. Non Medicare: 88342x2 = 4.94 RVUs
b. Medicare: G0461 = 2.47 RVUs

2. Multiple distinct antibody stains example: Skin specimen (single block) with Melan-A and separate S-100 stain.

a. Non Medicare: 88342 x 2 = 4.94 RVUs
b. Medicare: G0461 and G0462 = 4.38 RVUs

3. Cocktail stains example: Prostate biopsy specimen (one block) PIN4 cocktail stain including three separately identifiable antibodies (P504S, p63, and CK903):

a. Non Medicare: 88342 and +88343 x 2 = 6.29 RVUs
b. Medicare: G0461 = 2.47 RVUs.