Pathology/Lab Coding Alert

Know CPT's assay/stain distinction to pick the right code.

The adage to "always report the most specific CPT code" could ambush your estrogen receptor (ER) and progesterone receptor (PR) coding for breast cases. Let our experts help you sort out the difference between specific analyte and specific method to make sure you choose the right code -- every time.

1. Reserve 84233 and 84234 for Assays

If you're looking for specific codes when a surgical pathology report references estrogen and/or progesterone receptor testing, you can't miss 84233 (Receptor assay; estrogen) and 84234 (... progesterone). But are those always the right choice?

"The 84233 and 84234 definitions create a dilemma for coders reporting ER/PR tests," asserts Dennis Padget, MBA, CPA, FHFMA, president of DLPadget Enterprises Inc. and publisher of the Pathology Service Coding Handbook, in The Villages, Fla. "The question is whether you must report 84233/84234 because the definitions specify ER/PR, or if you can instead report a generic immunohistochemistry code such as 88342 (Immunohistochemistry, [including tissue immunoperoxidase], each antibody) for certain ER/PR testing." "Assay" resolves quandary: "Codes 84233 and 84234 describe laboratory tests for estrogen and progesterone receptors that use a biochemical ligand-binding assay method, such as dextran-coated charcoal assay," Padget says. But most labs evaluate ER/PR using immunohistochemistry, because clinical studies have consistently shown the superiority of immunohistochemistry over biochemical assay methods for ER/PR testing.

Bottom line: "If the lab performs an immunohistochemical analysis for ER or PR, you should not report 84233 or 84234, because immunohistochemistry is not an assay," Padget says. Reserve 84233 and 84234 for ER/PR assays.

2. Be on the Lookout for Immunohistochemistry

When the lab method involves immunohistochemistry (IHC) for tissue specimens, such as evaluating breast tumors for ER and PR status, you should look to the following codes to describe the service:

• 88342 -- Immunohistochemistry (including immunoperoxidase), each antibody
• 88360 -- Morphometric analysis, tumor immunohistochemistry (e.g., Her-2/neu,estrogen receptor/progesterone receptor), quantitative or semiquantitative, each antibody; manual
• 88361 -- ... using computer-assisted technology.

"Even though these code definitions are 'generic' in the sense that they don't specifically identify estrogen or progesterone receptors, you should use them for an ER or PR (or any other) immunohistochemistry antibody stain," Padget says.

3. Distinguish Qualitative/Quantitative Codes

Selecting among 88342, 88360, or 88361 requires knowing whether the immunohistochemistry analysis is qualitative or quantitative (including semiquantitative), and whether quantification uses computer-assisted technology or "manual" counting, including visual approximation. "You might use any of these three codes for ER, PR, Her- 2/neu, Ki-67, or any of several other IHC analyses," Padget says. For instance, an estrogen receptor immunostain might be qualitative (88342), quantified by a person counting or visually approximating stained cells in certain areas of the slide (88360), or quantified using an automated computerized system (88361).

4. Count Antibodies

You should report one unit of the appropriate code for each antibody stain, regardless of which antibody you're coding.

For instance: "Not infrequently, I'll order a p63 or smooth muscle specific actin stain for a needle core breast biopsy to confirm that an atypical glandular proliferation is, in fact, an invasive carcinoma. Then, I'll order ER/PR to evaluate the hormone receptor status of the tumor," says Christopher M. Flynn, M.D., a pathologist in Battle Creek, Mich.

If you don't know whether the immunohistochemistry evaluation is qualitative or quantitative/semi-quantitative (not to mention manual or computer assisted for the latter), you can't select the proper code. Assuming that all three antibodies in the preceding example involve manual quantification, you should code the case as 88360 x 3.

Count specimens: The preceding scenario involved multiple antibody stains for a single specimen -- a needle core breast biopsy. And you can see that the code definitions allow you to list one unit for each distinct antibody. But if you have multiple specimens, you can charge for individual immunohistochemistry stains for each specimen. In other words, you can code per antibody, per specimen.

Although "per stain per specimen" used to be the final word on the matter, pathologists may have new opportunities for special stains, thanks to a CMS policy change. Read all about it in "IHS Stain Unit Change Could Benefit Your Bottom Line," on page 66.