Pathology/Lab Coding Alert

• Right breast biopsy: Stage 1 adenocarcinoma, ER+, PR+; manual HER2 protein level +1
• Left breast biopsy: fibroadenosis, no special stains

Request: Sixteen days following the biopsy, the surgeon requested Ki67 testing for the right breast biopsy.

Findings: Manual IHC, report 32 percent Ki67

Avoid These Procedure Coding Pitfalls

Let’s break down the procedure coding for this case, step by step.

Step 1: Select the pathology exam code(s). Because the surgeon submits two, distinctly identified breast biopsy specimens, and the pathologist documents diagnosis specimen A and specimen B, you should report two units of 88305 (Level IV - Surgical pathology, gross and microscopic examination … Breast, biopsy, not requiring microscopic evaluation of surgical margins…).

Step 2: Identify immunohistochemistry (IHC) codes. The case involves four IHC procedures performed on the cancer tissue.

ER/PR: The ER and PR tests are qualitative, which is apparent because the pathologist reports the findings as positive or negative. Estrogen and progesterone are hormones, and some cancer cells have receptors that these hormones can bond to. The pathologist uses an immunostain to identify the presence or absence of these receptors, which they reported in this case as ER+/PR+. Code this as 88342 (Immunohistochemistry or immunocytochemistry, per specimen; initial single antibody stain procedure) and +88341 (… each additional single antibody stain procedure (List separately in addition to code for primary procedure)) because you have two distinct antibody stains on a single specimen (right breast biopsy).

HER2: The HER2 test reported for this case is a semiquantitative IHC test. You know this because the pathologist reports the findings as a “score” of +1. That means the pathologist provides an estimate of the amount of cell staining based on counting limited area(s) of the slide. The appropriate code for the test is 88360 (Morphometric analysis, tumor immunohistochemistry (eg, Her-2/neu, estrogen receptor/progesterone receptor), quantitative or semiquantitative, per specimen, each single antibody stain procedure; manual).

Clarification: HER2 is the name of both a protein and a gene that codes for the protein. Overexpression of the protein in breast tumor tissue (such as a +3 score) is associated with aggressive tumor growth and may indicate that the tumor will be susceptible to Herceptin therapy. The test for the protein is the IHC test described in this case. But labs might also do a test for the gene, and that’s a completely different test. If the IHC test is inconclusive (such as a 2+ score), the lab might also perform a gene amplification test such as 88365 (In situ hybridization (eg, FISH), per specimen; initial single probe stain procedure).

Ki67: The pathology report lists a percentage for Ki67, so you know it is a quantitative measure. “Pathologists often use Ki67 as a marker for cellular proliferation, which may indicate the likelihood that the cancer is invasive,” says R.M. Stainton Jr., MD, president of Doctors’ Anatomic Pathology Services in Jonesboro, Arkansas. The report also indicates that this is a manual evaluation of the slide. For those reasons, the appropriate code for the work is 88360.

DOS rule: The Medicare date of service (DOS) rule states that for clinical lab tests performed on a specimen stored for 30 days or fewer, you should use the date the specimen was taken as the DOS. That is, unless the specimen was taken from a hospital inpatient or outpatient and the test results didn’t guide treatment while in the hospital (which describes the Ki67 test). For the 14th through 30th day after the patient discharge, you should use the date you perform the test as the DOS.

Get the Diagnosis Right

You’ll need to make decisions at several points in the process of choosing the correct procedure codes for this case.

Consider: When you have two masses in different locations of the breast, both diagnosis codes should be reported, according to Melanie Witt, RN, MA, an independent coding expert based in Guadalupita, New Mexico.

First, you should code the pathologist’s right breast biopsy exam findings as C50.211 (Malignant neoplasm of upper-inner quadrant of right female breast). You should additionally report Z17.0 (Estrogen receptor positive status [ER+]). Remember that an ICD-10-CM note with the Z17 codes states, “code first malignant neoplasm of breast (C50.-). There is no specific ICD-10-CM code for PR or HER2 status.

For the left breast, report N60.22 (Fibroadenosis of left breast).