Pathology/Lab Coding Alert

Question: How many immunohistochemistry stains of can we charge for this case: one breast tissue block of labeled A1 stained for ER/PR; two sentinel lymph nodes in blocks B1, B2; and C1, C2, C3 processed for sentinel node protocol cytokeratin stains.

Tennessee Subscriber

Answer: You should report immunohistochemistry per antibody stain, per specimen. The number of blocks or slides that you assess does not impact coding. The case includes three specimens: breast and two sentinel lymph nodes. CPT does not bundle sentinel lymph nodes with breast tissue, although CPT does bundle regional lymph nodes with a mastectomy specimen.

Assuming that the lab performed qualitative immunohistochemistry for estrogen receptor (ER) and progesterone receptor (PR), you should report two units of CPT 88342 (Immunohistochemistry [including tissue immunoperoxidase], each antibody) for the two antibody stains that you performed on the A1 breast specimen. You should also report a single unit of 88342 for the cytokeratin stains from the two lymph node blocks labeled B1 and B2. The cytokeratin stains from the three lymph node blocks labeled C1, C2 and C3 warrant another unit of 88342.

Bottom line: Coding per stain, per specimen you should report 88342 x 4 -- that includes two stains for the first specimen and one stain for each of the other two specimens.

You should report certain ER/PR assays using a code introduced in CPT 2004 -- 88361 (Morphometric analysis; tumor immunohistochemistry [e.g., Her-2/neu, estrogen receptor/progesterone receptor], quantitative or semiquantitative). Although the code describes quantitative or semiquantitative morpho-metric analysis of tumor immunohistochemistry, Medicare has placed some further restrictions on the use of the code.

For a full discussion of when to report 88342 or 88361, see "Tumor Morphometry Update: Make Sure to Use 88342 for Medicare Manual IHC" in the August 2004 issue of Pathology/Lab Coding Alert.