Pathology/Lab Coding Alert

Reader Questions:

Recognize Multiplex Parameters

Published on Mon Feb 12, 2024

Question: The lab performs a triple antibody stain on a melanoma specimen using SOX10, which stains nuclei blue, PD-L1, which stains membranes brown, and CD8, which stains cytotoxic T-cells red. The pathologist evaluates the staining pattern for each antibody, which allows an interpretation of proliferation. How should we report this procedure?

Tennessee Subscriber

Answer: What you describe is a multiplex immunohistochemistry (IHC) stain procedure.

An IHC stain uses an antibody/antigen reaction to detect a specific target. You describe three separate stains in one procedure, each of which is separately identifiable on the slide: SOX10, CD8, and PD-L1.

Multiplex: When an IHC stain procedure involves multiple distinct targets and provides distinct results for each target, it is a multiplex test. On the other hand, if an IHC stain procedure involves multiple targets but provides a single result, it is not a multiplex test.

The appropriate code for this test is 88344 (Immunohistochemistry or immunocytochemistry, per specimen; each multiplex antibody stain procedure).

Avoid: Because this is one procedure that includes three stains, you should not report this as 88342 (Immunohistochemistry or immunocytochemistry, per specimen; initial single antibody stain procedure) and two units of +88341 (… each additional single antibody stain procedure (List separately in addition to code for primary procedure))