Question: Please explain why CCI bundles 88342 into 88323. If our pathologist consults on a case, why can't he charge for immuno-stains that he orders and interprets to reach a diagnosis? Montana Subscriber Answer: Your pathologist can bill for both the slide consultation and the immuno-stains -- under certain circumstances. Know the edits: You are correct that Medicare's National Correct Coding Initiative (CCI) lists 88342 (Immunohistochemistry [including tissue immunoperoxidase], each antibody) as a component of 88323 (Consultation and report on referred material requiring preparation of slides). The reason for the edit is for situations when the immuno-stain is already done. If your pathologist receives a case that includes slides that were already immuno-stained and interpreted, you should only code the consult -- 88323. On the other hand, if the pathologist receives unstained slides or a block and performs immunohistochemistry in his lab and interprets the slides as part of the overall case to reach a diagnosis, then you may charge 88342 in addition to 88323. Watch for modifier: Because the CCI edit is in place, you must use a modifier to let the payer know that your pathologist did perform a distinct staining service rather than interpreting already-stained slides. You should append modifier 59 (Distinct procedural service) to 88342 to override the edit pair. Reader Questions and You Be the Coder were prepared with the assistance of William Dettwyler, MT-AMT, president of Codus Medicus, a laboratory coding consulting firm in Salem, Ore.