Oncology & Hematology Coding Alert

ICD-10-CM Guidelines:

Perfect Your Oncology Dx Coding With These Guideline Takeaways

Published on Fri Jun 23, 2023

Hint: Remember to code first the reason for the encounter.

The chapter-specific guidelines accompanying the neoplasm codes in chapter 2 of ICD-10-CM can be confusing to new oncology coders. And those with more experience in oncology coding may have forgotten some of the key advice contained in guideline I.C.2.

But failure to abide by these guidelines can be catastrophic. So, here are the top takeaways from the I.C.2 guidelines, along with scenarios to test your knowledge and help you keep your oncology coding clean, correct, and compliant.

Takeaway 1: Code the Reason for the Encounter

ICD-10-CM guideline IV.G, which tells you to “list first the ICD-10-CM code for the diagnosis, condition, problem, or other reason for encounter/visit shown in the medical record to be chiefly responsible for the services provided,” is one of the overarching principles of diagnosis coding. This is especially true in oncology, which is why it is echoed in chapter-specific guideline I.C.2.a. This states, “if the malignancy is chiefly responsible for occasioning the patient admission/encounter and treatment is directed at the primary site, designate the primary malignancy as the principal/first-listed diagnosis.”

But the guideline goes on to note an important exception to this rule. It tells you to “assign the appropriate Z51.- (Encounter for other aftercare and medical care) code as the first-listed or principal diagnosis, and the underlying diagnosis or problem for which the service is being performed as a secondary diagnosis” when “the administration of chemotherapy, immunotherapy or external beam radiation therapy is chiefly responsible for occasioning the admission/encounter.”

Here’s why: “We typically turn to the Z51.- aftercare codes when a patient is no longer receiving treatment but requires continued care. While the Z51.- category represents other aftercare and medical care, the Z51.0 [Encounter for antineoplastic radiation therapy] and Z51.1- [Encounter for antineoplastic chemotherapy and immunotherapy] codes are appropriate, and should be listed as the primary diagnosis, when a patient presents exclusively for antineoplastic radiation therapy, chemotherapy, or immunotherapy. An additional code should be used to capture the neoplasm requiring treatment.

Remember that medical record drives code selection and must clearly support the reason for the patient encounter,” Leah Fuller, CPC, COC, senior consultant at Pinnacle Enterprise Risk Consulting Services, Kannapolis, North Carolina adds.

For example: A patient with prostate cancer reports to your practice for chemotherapy. In this situation, you’ll assign Z51.11 (Encounter for antineoplastic chemotherapy) as the principal diagnosis before the cancer diagnosis code: C61 (Malignant neoplasm of prostate).

Takeaway 2: Sequence Complications

As you will often be called upon to code encounters where a patient is being treated for complications resulting from their cancer, committing guidelines I.C.2.c.1-4 to memory is never a bad idea. The guidelines list four common complications and tell you to code them like this:

Treatment only for anemia associated with the malignancy: Code the neoplasm first, followed by D63.0 (Anemia in neoplastic disease) or another appropriate anemia code.
Treatment only for anemia associated with chemotherapy, immunotherapy, and radiation therapy: Select the appropriate code for the anemia first, followed by the appropriate neoplasm code, and either T45.1X5- (Adverse effect of antineoplastic and immunosuppressive drugs) or Y84.2 (Radiological procedure and radiotherapy as the cause of abnormal reaction of the patient, or of later complication, without mention of misadventure at the time of the procedure), as applicable.
Treatment only for dehydration associated with the malignancy: Sequence the dehydration first, followed by the code(s) for the malignancy.
Treatment only for complications associated with surgery for the malignancy: Assign the code for the complication only.

For example: Your provider treats a patient who is taking chemotherapy for breast cancer in the central portion of her right breast. In the encounter, the provider only treats the patient for anemia due to the chemotherapy. It is the patient’s first encounter for this particular condition.

For this encounter, you’ll assign:

D64.81 (Anemia due to antineoplastic chemotherapy)
C50.111 (Malignant neoplasm of central portion of right female breast)
T45.1X5A

Takeaway 3: Understand Overlapping Sites

The general guidelines for I.C.2 tell you “a primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 (‘overlapping lesion’), unless the combination is specifically indexed elsewhere.”

So, you would assign C34.81 (Malignant neoplasm of overlapping sites of right bronchus and lung) for a patient diagnosed with multiple neoplasms in the right lung that are touching each other. Note the 4th character, 8, is used throughout the malignant neoplasm codes to specify the overlapping nature of the neoplasm.

However, general guideline I.C.2 also tells you “codes for each site should be assigned … for multiple neoplasms of the same site that are not contiguous such as tumors in different quadrants of the same breast.”

Do this: A provider diagnoses a patient with multiple neoplasms in the right main bronchus, the right upper lobe, and the right lower lobe. If the provider documents they are not overlapping, your coding in this situation would look like:

C34.01 (Malignant neoplasm of right main bronchus)
C34.11 (Malignant neoplasm of upper lobe, right bronchus or lung)
C34.31 (Malignant neoplasm of lower lobe, right bronchus or lung)

Takeaway 4: Know When to Use a Personal History Code

The guidelines involved in this last takeaway, I.C.2.m and n, can be tricky to apply. In the case of I.C.2.m, you are instructed that “a code from category Z85, Personal history of malignant neoplasm, should be used to indicate the former site of the malignancy … when a primary malignancy has been previously excised or eradicated from its site, there is no further treatment (of the malignancy) directed to that site, and there is no evidence of any existing primary malignancy at that site.”

But guideline I.C.2.n is not quite as straightforward, as it informs you there are codes for leukemia, multiple myeloma, and malignant plasma cell neoplasms when they are in remission and also codes for a personal history of these conditions. Unlike guideline I.C.2.m, guideline I.C.2.n does not tell you when to apply a remission code from C90.- (Multiple myeloma and malignant plasma cell neoplasms) or when to apply Z85.6 (Personal history of leukemia) or Z85.79 (Personal history of other malignant neoplasms of lymphoid, hematopoietic and related tissues).

Do this: Look to see if your provider’s notes state whether the remission is partial or complete. In cases of partial remission, some of the signs and symptoms of the condition are still present, so you will assign the 5th character 1 to the appropriate leukemia code. For example, you would assign C92.01 (Acute myeloblastic leukemia, in remission) to a patient still showing signs and symptoms of acute myeloid leukemia (AML).

However, in cases of complete remission — if all the signs and symptoms of the malignancy have disappeared or been eradicated without any evidence it still exists and/or the patient is not receiving any treatment for the leukemia — and if provider documentation supports it, you would assign Z85.6.

Before assigning a character for remission, however, remember to follow the advice in ICD-10-CM guideline I.C.2.n, which says, “if the documentation is unclear as to whether the leukemia has achieved remission, the provider should be queried.”