Pathology/Lab Coding Alert

Beware unit of service impact.

When your pathologist consults on material referred from an outside lab, opportunities abound to capture ancillary-service pay.

But opportunities come with pitfalls, and our experts can help you recognize the difference.

Introducing the Case

The pathologist receives two blocks of prostate chips from a single prostate biopsy with a request for consultation from the referring physician at another institution.

The lab accessions the case, describing block A and block B, and preparing hematoxylin and eosin (H&E) slides from each block. The pathologist examines the slides and determines the need for additional stains.

Noting xanthogranulomatous tissue in both blocks, the pathologist examines additional stained slides to aid in differential diagnosis of adenocarcinoma and nonspecific granulomatous prostatitis (NSGP). The preparations include acid-fast bacillus (AFB) and early growth response-1 (ERG-1) stained slides from both blocks, and PIN-4 stained slides from block B.

Coding the Case

You should report the pathology consultation as 88323 (Consultation and report on referred material requiring preparation of slides) rather than 88321 (Consultation and report on referred slides prepared elsewhere) because the case involves de novo slide preparation from referred material using routine and special stains.

Although you receive two blocks, you should report just one unit of 88323. Based on AMA instruction regarding the pathology consultation codes 88321-88325, the unit of service is the “case,” not the specimen, as it is for surgical pathology evaluation codes 88300-88309 (Level … – Surgical pathology … examination …). “Case” refers to material extracted on a single date of service during a single surgical procedure from an anatomic site. The case often reflects the accession from the referring entity. The prostate biopsy blocks in this example represent a single case.

For Medicare, the unit of service is more stringent, limited to one pathology consultation code per date of service. The National Correct Coding Initiative (NCCI) Policy Manual states, “CMS payment policy allows only one unit of service for CPT^® codes 88321, 88323, and 88325 per beneficiary per provider on a single date of service.”

Bottom line: Regardless of the payer in this example, you’re dealing with one unit of 88323.

Capture the Stains

Rules for reporting 88323 allow you to report stains that your lab performs de novo on the referred material. You should generally use the stain codes the same way you would if you were reporting stains for a surgical pathology case.

The case description involves preparation and interpretation of the following stains:

• H&E on slides from two blocks
• AFB on slides from two blocks
• ERG-1 on slides from two blocks
• PIN-4 on slides from one block.

H&E: “This is a standard stain, so you won’t report an additional code for preparing these slides. The 88323 payment rate accounts for preparing slides with H&E staining,” says R.M. Stainton Jr., MD, president of Doctors’ Anatomic Pathology Services in Jonesboro, Ark.

AFB: The AFB stain is for microorganisms, so the appropriate code is 88312 (Special stain including interpretation and report; Group I for microorganisms (eg, acid fast, methenamine silver)). A CPT^® text note following 88312 states, “Report one unit of 88312 for each special stain, on each surgical pathology block, cytologic specimen, or hematologic smear.” That means you can report two units of 88312 in this case, because the pathologist examines AFB stained slides from both blocks.

ERG-1: This is an immunohistochemical (IHC) marker that identifies vascular differentiation associated with rapid cell growth, often expressed in prostate adenocarcinomas. As an IHC stain, you should code this stain using 88342 (Immunohistochemistry or immunocytochemistry, per specimen; initial single antibody stain procedure). “Because the code defines the unit of service as ‘per specimen,’ you should report just one unit of 88342 despite examining slides from two blocks,” says Peggy Slagle, CPC, coding and compliance manager for Regional Pathology Services at the University of Nebraska Medical Center in Omaha.

PIN-4: Pathologists often evaluate prostate tissue using PIN-4, which is a multiplex IHC stain involving three distinct markers such as p63, cytokeratin high molecular weight (CK HMW), and P504S to aid in differential diagnosis of prostate carcinoma or prostate intraepithelial neoplasia (PIN). The pathologist can individually interpret components of this triple stain, with p504S staining cytoplasm red in adenocarcinoma cells, p63 staining basal cell nuclei brown when PIN is present, and CK HMW staining normal/benign prostate gland cells brown. Because this is a multiplex stain, you should report 88344 (Immunohistochemistry or immunocytochemistry, per specimen; each multiplex antibody stain procedure).

As with 88342, the “specimen” unit of service for 88344 means that you should report just one unit of the code in this case. Despite the fact that the pathologist identifies three distinct stains on the slide(s), you should not bill three units of 88344 for a single PIN-4 specimen stain. “The 88344 code already accounts for multiple, separately-interpreted antibody stains,” Slagle says.

Beware bundling: NCCI bundles all of the stain codes in this case (88312, 88342, 88344) as column 2 codes with 88323. That’s because you shouldn’t bill the stain codes if the pathologist reviews special stains prepared by the referring physician. But because the pathologist in this case prepares and evaluates these slides de novo, you can report the codes and override the edit pair with a modifier such as 59 (Distinct procedural service) or XE (Separate encounter, a service that is distinct because it occurred during a separate encounter).

Similarly, NCCI bundles 88342 as a column 2 code with 88344, because 88344 includes multiple IHC stains, and you shouldn’t unbundle those stains and separately report them as 88342. In this case, the 88342 is a distinct IHC stain from any included in the 88344 code, so you can override the edit pair with the appropriate modifier.