Pathology/Lab Coding Alert

Question: Our pathologist examined a breast biopsy and evaluated stained slides for ER, PR, and Her 2-neu. Five weeks later, the treating physician contacted the pathologist, requesting AE1/AE3 antibody stain for the same biopsy tissue. How should we code this?

Minnesota 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 ...). For the initial immunohistochemistry (IHC) stains for estrogen receptor (ER), progesterone receptor (PR) and Her-2/neu, you should list 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)).

You should bill the AE1/AE3 antibody stain that you performed five weeks later as a single unit of 88342. Although this stain uses two histochemical antibodies, it functions as a single-color stain to detect the presence of cells expressing both low- and high-molecular-weight cytokeratins. That means you should report AE1/AE3 as a single unit of 88342.

Notice date: If your pathologist had performed the AE1/AE3 on the same date as the initial IHC stains, you would have reported the service as an additional unit of +88341 instead of coding the test as 88342. But given that the test was five weeks later, the pathologist should use the date of service (DOS) for the AE1/AE3 test as the date that the pathologist pulls the biopsy from storage to perform the new test. On that date, the pathologist performs an initial IHC stain, which is 88342.

Recall: Date of service requirements are different for clinical lab tests and technical or professional components of pathology services, or certain tests such as molecular pathology. To review the DOS rules, visit recent articles in Pathology/Lab Coding Alert: "Take Advantage of 14-Day Rule Change" in Vol. 19, No. 4 and "Forget Professional Component DOS Instruction" in Vol. 19, No. 3