Pathology/Lab Coding Alert

Distinguish anatomic and clinical tests.

If you want to unscramble the four code families (and more!) that describe in situ hybridization (ISH) procedures you might encounter in your claims reporting, we’ve got the primer for you.

Basics: ISH is a lab method that uses a nucleic acid (DNA or RNA) sequence (called a “probe”) that carries a label such as a fluorescent dye. The procedure involves joining the labeled probe to a target nucleic acid sequence in the test specimen in a process called “hybridization.” Depending on the probe and the specimen, the resulting hybridization can help the clinician diagnose and characterize certain cancers, or evaluate certain chromosomal or genetic abnormalities.

Problem: Because labs use this fundamental process on disparate specimens for a wide range of diagnostic purposes, you’ll find “ISH” listed in many CPT^® codes — and that’s the source of much coder confusion.

Solution: Let us break it down for you so you can code ISH cases with confidence.

Follow Clinical Context to Find Code Family

You’ll find the four CPT^® ISH code families and some unique ISH codes by first identifying the clinical context.

Histopathology/cytopathology: “Pathologists may evaluate tissue or cytology specimens using an ancillary ISH service, often as part of cancer diagnosis,” says R.M. Stainton Jr., MD, president of Doctors’ Anatomic Pathology Services in Jonesboro, Ark. In those cases, you should turn to the following codes:

• 88365 (In situ hybridization (eg, FISH), per specimen; initial single probe stain procedure)
• +88364 (… each additional single probe stain procedure (List separately in addition to code for primary procedure))
• 88366 (… each multiplex probe stain procedure)
• 88367 (Morphometric analysis, in situ hybridization (quantitative or semi-quantitative), using computer-assisted technology, per specimen; initial single probe stain procedure)
• +88373 (… each additional single probe stain procedure (List separately in addition to code for primary procedure))
• 88374 (… each multiplex probe stain procedure)
• 88368 (Morphometric analysis, in situ hybridization (quantitative or semi-quantitative), manual, per specimen; initial single probe stain procedure)
• +88369 (… each additional single probe stain procedure (List separately in addition to code for primary procedure))
• 88377 (… each multiplex probe stain procedure).

Exception 1: CPT^® provides two specific codes to accommodate ISH evaluation for urinary tract cytology specimens:

• 88120 (Cytopathology, in situ hybridization (eg, FISH), urinary tract specimen with morphometric analysis, 3-5 molecular probes, each specimen; manual)
• 88121 (… using computer-assisted technology).

Exception 2: If CPT^® provides a Proprietary Laboratory Analysis (PLA) code for the ISH test, such as the following two codes, you must use the specific PLA code:

• 0009U (Oncology (breast cancer), ERBB2 (HER2) copy number by FISH, tumor cells from formalin-fixed paraffin-embedded tissue isolated using image-based dielectrophoresis (DEP) sorting, reported as ERBB2 gene amplified or non-amplified)
• 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).

You’ll typically use these codes in addition to surgical pathology codes 88302-88309 (Level … Surgical pathology, gross and microscopic examination …) or cytopathology codes such as 88172-88173 and +88177 (Cytopathology, evaluation of fine needle aspirate …) or 88104-88112 (Cytopathology…) for tissue or cytology specimens. The tests normally aid in the diagnosis and characterization of cancers.

Molecular cytogenetics: If you’re coding for a clinical lab test as an ISH test for a cytogenetics case, not a histopathology or cytopathology case, you should turn to a different set of codes, as follows:

• 88271 (Molecular cytogenetics; DNA probe, each (eg, FISH))
• 88272 (… chromosomal in situ hybridization, analyze 3-5 cells (eg, for derivatives and markers))
• 88273 (… chromosomal in situ hybridization, analyze 10-30 cells (eg, for microdeletions))
• 88274 (… interphase in situ hybridization, analyze 25-99 cells)
• 88275 (… interphase in situ hybridization, analyze 100-300 cells)
• 88291 (Cytogenetics and molecular cytogenetics, interpretation and report).

The specimen for these tests may be blood or amniotic or other fluid, or may be tissue or cell culture. “Clinicians may order these tests to evaluate certain chromosomal or genetic abnormalities, often as part of a larger cytogentic study, possibly involving other codes in the range 88230-88299,” says William Dettwyler, MT AMT, president of Codus Medicus, a laboratory coding consulting firm in Salem, Ore.

Focus on Details Within Families

Once you’ve zeroed in on the correct code family, you need to distinguish between the individual codes using details such as whether the test is quantitative, computer assisted, or analyzes a certain number of cells. Here’s a breakdown within code groups:

88365-88377: These codes first divide down along the lines of whether the test is a qualitative “stain” procedure (codes +88364-88366), or a quantitative/semiquantitative evaluation (codes 88367-88377). Within 88367-88377, you can further subdivide the codes according to analyses that use computer assisted technology (88367, +88373, 88374), or manual quantification methods (88368, +88369, 88377).

Unit of service: Although you have three code families (the qualitative family, the quantitative/manual family, and the quantitative/computer assisted family), they are similar in how you report the unit of service. Each code family begins with a parent code for the first, single probe procedure. In addition to these codes for the “initial single probe,” each code family also has an indented, add-on code to report additional single probes. Finally, each code family has a code for a “multiplex probe stain procedure.” Use a single unit of these codes if the ISH test identifies multiple antibodies or probes in a single procedure.

88120-88121: As with codes 88367-88377, you can distinguish between the 88120 and 88121 based on whether the quantification involves manual or computer-assisted methods.

88271-88275: Code 88271 is essentially a qualitative stain code, but the difference between 88272-88275 is a matter of counting the number of cells evaluated. CPT^® provides parenthetic examples, such as “eg, for microdeletions” in 88273, but those instances do not limit when you can use the code.

Unit of service: Molecular cytogenetics codes for cellular ISH are “building block” codes. You should select the appropriate hybridization code (88272-88275) based on the number of cells analyzed and whether the lab used metaphase or interphase hybridization. In addition to the hybridization, a single ISH study might involve multiple DNA probes, and you should report one unit of 88271 for each probe.