Oncology & Hematology Coding Alert

Understand these core codes and how to apply them.

Breast cancer coding may seem simple on the surface, but a closer look reveals many nuances that can be easily missed. This made the HEALTHCON Regional 2024 presentation “Breast Cancer Coding” extremely valuable to anyone involved in oncology coding.

These articles based on the presentation will take you through all the essential steps for comprehensive breast cancer reporting, as outlined by Halee Garner, CPC, CPMA, CHONC, CCA, CPhT, AAPC Approved Instructor, quality assurance coordinator for Florida Cancer Specialists & Research Institute in Fort Myers, Florida.

First, let’s begin with her take on how to document breast cancer diagnoses and mastectomies.

Know How the ICD-10-CM Codes Work

Garner began with a refresher on how the C50.- (Malignant neoplasm of breast) codes are broken down. The 4^th characters used in the C50.- codes provide location information, and Garner offered the following tips about how report the characters correctly:

• The quadrant code designations (4^th character 2 = upper, inner; 3 = lower, inner; 4 = upper, outer, 5 = lower, outer) mirror each other; in other words, “they are not going in the same direction,” according to Garner, which you can see in the diagram provided by the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) Program.
• The axillary tail code designation (4^th character 6) includes a lot of the different lymph nodes along with the armpit and side area.
• The overlapping sites code designation (4^th character 8) indicates that the breast cancer is located in more than one quadrant or other anatomic location as long as the sites are contiguous.

Importantly, C50.4- (Malignant neoplasm of upper-outer quadrant of breast) “is going to be the most commonly used code, as 50 percent of patients with breast cancer have it in that upper outer quadrant,” Garner explained.

In order to assign the 5^th character for gender, you “must go by sex assigned at birth,” Garner noted, pointing out that less than 1 percent of breast cancer patients are, in fact, male. And to complete the code, you’ll need to assign a 6^th character for laterality.

Finally, the 6^th character identifies the documented laterality (right, left) or if not documented, unspecified.

Using the table below, you’ll plug all of that information to locate the most specific code for a patient’s breast cancer diagnosis:

Note these secondary site codes: While secondary breast cancer is not common, primary breast cancer commonly leads to secondary cancer in the following:

• C78.0- (Secondary malignant neoplasm of lung)
• C78.7 (Secondary malignant neoplasm of liver and intrahepatic bile duct)
• C79.2 (Secondary malignant neoplasm of skin)
• C79.31 (Secondary malignant neoplasm of brain)
• C79.51 (Secondary malignant neoplasm of bone)

And remember the ER+/ER- estrogen receptor codes: Garner also offered the reminder that while ICD-10-CM for 2025 has expanded the Z17.- code category to include the receptor status of other hormones and factors, the estrogen receptor codes represented by Z17.0 (Estrogen receptor positive status [ER+]) and Z17.1 (Estrogen receptor negative status [ER-]) have not changed. These two codes are utilized for malignant breast cancers and will always be secondary to the primary cancer code.

Master Mastectomy Coding

Garner then reviewed coding for mastectomy procedures. The codes include 19303 (Mastectomy, simple, complete), which is the basic mastectomy code used when the surgeon only removes the breast and nothing else, and 19305-19306 (Mastectomy, radical …) and 19307 (Mastectomy, modified radical …), which are for removal of more than the breast as specified by the code descriptors.

To help you report the codes correctly, Garner offered the following advice:

• All the mastectomy codes are unilateral, so you’ll need to add RT (Right side), LT (Left side), or 50 (Bilateral procedure) modifiers as appropriate and per payer preference.
• Never use 19300 (Mastectomy for gynecomastia) for female mastectomies, as it is used for the procedure to reduce male breasts.
• The National Correct Coding Institute (NCCI) allows you to use different mastectomy codes for the same encounter. That’s because different breasts may require different procedures.
• However, for all CPT^® mastectomy codes, the medically unlikely edit (MUE) is 1, meaning 1 unit of the procedure is the maximum unit of service (UOS) that you report on a claim by the same provider for the same beneficiary on the same date of service. As each breast can only be removed once, this particular MUE is easy to understand.
• Intraoperative clip placement is not separately reported.

Garner also offered the reminder to bookmark the Z90.1- (Acquired absence of … breast and nipple(s)) codes once the patient has undergone the mastectomy procedure.

In Part 2, we’ll look at Garner’s advice on how to document breast reconstruction and common intravenous (IV) breast cancer drug treatments, and how to report breast cancer symptoms and diagnostics.

Bruce Pegg, BA, MA, CPC, CFPC, Managing Editor, AAPC