Pathology/Lab Coding Alert

Question: We have a pathology report for a breast biopsy exam, and the report states, “The tumor demonstrates HER2/ neu amplification (3.1:1 ratio) by FISH procedure.” How should we code this?

Tennessee Subscriber

Answer: You should code the breast biopsy exam as 88305 (Level IV - Surgical pathology, gross and microscopic examination… Breast, biopsy, not requiring microscopic evaluation of surgical margins …).

Choosing the correct fluorescence in situ hybridization (FISH) code depends on deciding if the procedure is single or multiplex, qualitative or quantitative, and manual or computer assisted.

Because the pathologist reports the FISH test as a ratio, that means the procedure involves two probes — one for the HER2/neu gene and one for the chromosome 17 centromere (CEP17). A FISH test that simply enumerates the HER2/ neu gene would not be reported as a ratio. In other words, the FISH test in this case is multiplex. Multiplex FISH is a single test that uses multiple (two, in this case) distinct, separately-identifiable probes.

Because each signal is separately identifiable under the microscope, the clinician or the computer software can quantify the HER2/neu gene signal and the chromosome signal. Once quantified, the ratio allows the pathologist to know if HER2/neu is “amplified,” meaning that there are more copies of the gene than expected for the number of chromosome signals present in the specimen.

Similarly, because the result is a ratio, we know that the test in question is quantitative, not qualitative. The computer system or clinician “counted” the HER2/new targets and the CEP17 targets.

The fact that the FISH test is multiplex and quantitative narrows your code choice to the following:

• 88374 (Morphometric analysis, in situ hybridization (quantitative or semi-quantitative), using computer-assisted technology, per specimen; each multiplex probe stain procedure)
• 88377 (Morphometric analysis, in situ hybridization (quantitative or semi-quantitative), manual, per specimen; each multiplex probe stain procedure)

Problem: The pathology report doesn’t indicate if the test is “manual” or “computer assisted.” The pathologist must indicate that information in the pathology report for you to be able to correctly assign the procedure code for the HER2/neu FISH test.

Clinical: HER2/neu amplification has important implications for prognosis and treatment options for breast cancer patients.