Oncology & Hematology Coding Alert

Hint: Treatment documentation is key.

One of the most common areas of confusion when it comes to oncology coding is when to report a patient’s malignancy as active or personal history.

Here are some great tips to help you correctly assign an active or personal history code the next time you are confronted with the problem.

Know What the Guidelines Have to Say

The ICD-10-CM guidelines are always the best place to start in determining proper code assignment. According to I.C.2.m. of the 2025 ICD-10-CM guidelines, you should code a primary malignancy as active when there is treatment directed at the site, even if it has been excised. When there is treatment, such as chemotherapy, radiation therapy, or even additional surgical interventions directed to the site of the malignancy, the malignancy should be coded as active until all treatment has been completed and the provider determines there is no evidence of malignancy.

On the other hand, when a malignancy has been excised, there is no evidence of the malignancy existing at the site, and there is no further treatment directed at the site, you should assign a personal history code. Keep in mind that you can only assign a personal history code from Z85.- (Personal history of malignant neoplasm) when coding for a former site of a primary malignancy. Assign Z85.89 (Personal history of malignant neoplasm of other organs and systems) for either a primary or secondary malignancy.

Documentation Is Essential

The provider’s documentation is key to allowing coders to accurately assign diagnosis codes. The provider must paint the full picture of the current status of the malignancy. Often, coders are left wondering which codes should be assigned because the documentation is not clear.

The following two scenarios illustrate how confusion can creep into your coding when trying to determine if the patient’s condition is active.

Scenario 1: A provider documents that a patient has undergone a mastectomy of the left breast. On first thought, you may want to code this with a personal history code because of the absence of the patient’s left breast. However, the provider’s documentation indicates that the patient is receiving radiation treatment to the same area of the left breast for the malignancy.

In this case, the coder should assign an active cancer code from the C50.- (Malignant neoplasm of breast) series of codes in Chapter 2 of the ICD-10-CM code book.

Scenario 2: The provider diagnosed a patient with a melanoma on the right forearm. The provider excised the melanoma, and all margins were clear. If the patient is not receiving any treatment beyond the removal on subsequent visits and there is no current evidence of disease in the supporting documentation, in this case, you could assign a personal history code. For this scenario, use Z85.820 (Personal history of malignant melanoma of skin).

Identify Key Elements in the Documentation

In order to select an appropriate code, you need to pull specific key elements from the provider’s documentation and determine the accurate diagnosis codes based on these key elements.

Active or history: Identify if there is a current active neoplasm or if any treatment is being directed to a neoplasm site. If it is unclear, query the provider.

Location: Where is the neoplasm located? If the patient has cancer in more than one location, this could help you determine which of the sites is being actively treated.

Secondary site: Is there a secondary site that is affected? If the patient has a cancer that has metastasized, you will need to know whether the primary or secondary site is being treated to know whether or not to assign an active or history code.

Behavior of the neoplasm: Is the neoplasm malignant, in-situ, uncertain behavior (based on pathology), or benign? Again, the behavior of the cancer will determine if and how it is being treated, which will, in turn, determine code allocation.

Keep in mind, there are other caveats to diagnosis coding in the oncology specialty, but these are a few to watch out for.

Note: Be cautious when using documentation that leaves uncertainty based on provider’s statements such as likely, probable, consistent with, or any other language that shows uncertainty of the diagnosis. “In this circumstance, you should typically report signs and symptoms for the encounter. However, if there is reason to believe a more specific diagnosis should be reported, a query to the provider may be appropriate,” advises Leah Fuller, CPC, COC, senior consultant, Pinnacle Enterprise Risk Consulting Services LLC, Centennial, Colorado.

Don’t Miss Z08

Another code that is often missed by oncology specialty coders is Z08 (Encounter for follow-up examination after completed treatment for malignant neoplasm). You should assign code Z08 to explain that continued surveillance is necessary after treatment has been completed for a malignancy and you can assign it following any type of medical or surgical treatment. When assigning this code, the documentation must indicate that there is no further malignancy and the treatment has been completed. If that is the case, you should then assign a personal history code from Z85.- in addition to Z08. In such instances, Z08 would be sequenced first with the Z85.- code in the secondary slot on the claim form.

While ICD-10-CM guidelines for coding active and history neoplasms have not changed for 2025, it is still important for you to stay up to date on the latest coding guidance. That means monitoring annual ICD-10-CM code and guideline updates to stay on top of any new active or history neoplasm codes. Beginning Oct. 1, 2024, for example, you will have many additions, deletions, and revisions in ICD-10-CM Chapter 2, including more than 60 new and deleted codes specifically related to lymphomas as reported in Oncology and Hematology Coding Alert, Vol. 26, No. 8 (2024). So, be sure to review the ICD-10-CM code book for the date of service when coding active diagnoses, which for dates of service from Oct. 1, 2024, to Sept. 30, 2025, will be the ICD-10-CM FY2025 version.

Nikki Taylor, MSHCI, COC, CPC, CPCO, CPMA, CRC, AAPC Approved Instructor McKesson