Pathology/Lab Coding Alert

Remember: report ISH per specimen, then per procedure.

Ancillary tests using in situ hybridization (ISH) show up in many clinical situations and many CPT^® codes, and that can leave you scratching your head.

Study the three following scenarios to make sense of the coding options so you can report your next ISH case with confidence.

Tip: Although ISH procedures often use a fluorescent tag (FISH procedures), the CPT^® codes for ISH include other tags, such as chromogenic ISH (CISH).

Case 1: Don’t Make this MD Mistake

A urologist submits a urine specimen for a patient with hematuria to rule out bladder cancer. The lab performs a UroVysion fluorescence in situ hybridization (FISH) assay using FISH probes for aneuploidy in chromosomes 3,7, and 17 as well as 9p2 locus deletion, with computer assisted examination of 25 cells and requested interpretation of results by the PhD clinical pathology lab manager.

Do this: Code the UroVysion test as 88273 (Molecular cytogenetics; chromosomal in situ hybridization, analyze 10-30 cells (eg, for microdeletions)). With appropriate documentation and final report, you should additionally bill the lab manager interpretation as 88291 (Cytogenetics and molecular cytogenetics, interpretation and report).

That answer may surprise you, because CPT^® provides two specific codes for urinary tract specimens evaluated using FISH cytopathology: 88120 (Cytopathology, in situ hybridization (eg, FISH), urinary tract specimen with morphometric analysis, 3-5 molecular probes, each specimen; manual) and 88121 (… using computer assisted-technology).

Problem: Codes 88120 and 88121 are physician codes, and this case specifies that the clinical laboratory director, who is not an MD or DO, oversees the test and provides the interpretation. Because of the “who” in this case, you have to change the “what” from a physician code to a clinical lab code.

Notice: If a pathologist had been the lab manager overseeing the test performance and providing an interpretation of results, you would have billed 88121 in this case. Code 88121 is a global code that includes a technical component (which you could report separately using modifier TC, Technical component) and a professional component (which you could report separately using modifier 26, Professional component). That means billing 88121 includes both the technical work of performing the UroVysion test and the pathologist’s interpretation and report on the findings.

Case 2: Identify Multiplex FISH for HER2/neu

The pathologist performs a breast biopsy exam and a FISH test on the tissue to detect amplification of the HER2/neu gene. The FISH test uses computer assisted technology to quantify amplification of the HER2/neu gene relative to the signal from the chromosome 17 centromere (CEP17). The FISH ratio reported by this test is 3.2 to 1, meaning that the specimen is HER2/neu positive.

Coding: First, you should report the pathology biopsy exam as 88305 (Level IV - Surgical pathology, gross and microscopic examination …Breast, biopsy, not requiring microscopic evaluation of surgical margins …). You should additionally bill the FISH test as 88374 (Morphometric analysis, in situ hybridization (quantitative or semi-quantitative), using computer-assisted technology, per specimen; each multiplex probe stain procedure).

Why multiplex: The documentation indicates that FISH HER2/neu is a multiplex test as evidenced by the fact of two probes – one for the HER2/neu gene and one for CEP17. Further, because the two probes are not distinct procedures and the two probes contribute to a single clinical finding, which is a ratio, you should not code this as two individual FISH tests using codes such as 88367 (Morphometric analysis, in situ hybridization (quantitative or semi-quantitative), using computer-assisted technology, per specimen; initial single probe stain procedure) and +88373 (… each additional single probe stain procedure (List separately in addition to code for primary procedure)).

More details: “You have other multiplex ISH code choices besides 88374 based on whether the test is qualitative or quantitative; manual or computer assisted,” says Peggy Slagle, CPC, coding and compliance manager for Regional Pathology Services at the University of Nebraska Medical Center in Omaha.

The other multiplex ISH codes include 88377 (Morphometric analysis, in situ hybridization (quantitative or semi-quantitative), manual, per specimen; each multiplex probe stain procedure) and 88366 (In situ hybridization (eg, FISH), per specimen; each multiplex probe stain procedure). Because 88374 describes a computer-assisted assay and a quantitative or semiquantitative result (a ratio of HER2/neu and CEP17 levels), the manual code (88374) and qualitative code (88366) are not appropriate for this scenario.

In this case, the ratio 3.2:1 indicates that the HER2/neu gene is amplified, meaning that there are more copies of the gene than expected for the number of chromosome signals present in the specimen. “HER2/neu amplification has important implications for prognosis and treatment options for breast cancer patients,” says R.M. Stainton Jr., MD, president of Doctors Anatomic Pathology Services in Jonesboro, Ark.

Case 3: PLA Codes Trump Category 1

The lab receives a prostate needle biopsy specimen, which the pathologist examines. The lab also carries out a gene expression profiling FISH test protocol from Mayo Clinic. The test involves applying special DNA and RNA probes that selectively attach to target segments of DNA or RNA associated with ASAP1, HDAC9, CHD1 and PTEN genes, which can be analyzed under a fluorescence microscope to detect and localize the target(s) in the tissue. Using the FISH and other clinical data, the lab carries out a special algorithmic analysis to predict the probability of a high-grade prostate tumor.

Solution: You should report the pathologist’s biopsy exam as 88305 (… Prostate, needle biopsy …). For the FISH gene expression profile test, report 0053U ((Oncology (prostate cancer), FISH analysis of 4 genes (ASAP1, HDAC9, CHD1 and PTEN), needle biopsy specimen, algorithm reported as probability of higher tumor grade).

Beware: Looking to CPT^® Category 1 FISH codes, you might think you could code this case as 88365 (In situ hybridization (eg, FISH), per specimen; initial single probe stain procedure)) and three units of +88364 (… each additional single probe stain procedure (List separately in addition to code for primary procedure)), or a single unit of 88366. Either venture would be wrong.

First, realize that the FISH codes are “per specimen,” then “per procedure.” If a single procedure involves multiple probes, you should turn to the multiplex code(s), not the individual probe codes – so that rules out reporting 88365 and +88364 in this case. Even so, selecting 88366 for the described test would be wrong.

Here’s why: The test performed is a proprietary laboratory developed test by Mayo Clinic that has a specific proprietary laboratory analyses (PLA) code – 0053U. According to CPT^® guidelines, if a PLA code is available, it takes priority over any Category 1 code. Conversely, you should not use a PLA code for any procedure other than the specified test by the specific lab or manufacturer.