The ICD-10-CM Neoplasm Table lists anatomic sites down the left side and six columns across: Malignant Primary, Malignant Secondary, Ca in situ, Benign, Uncertain Behavior, and Unspecified Behavior. When the histology is documented, look up that term in the Alphabetic Index first to learn which column to use, then select the code for the site and confirm it in the Tabular List.
How the Neoplasm Table Is Organized
The Neoplasm Table sits in the Alphabetic Index. Each row is a body site, and each column is a type of behavior. For example, the FY2027 row for liver reads:
| Column | What it means | Liver |
|---|---|---|
| Malignant Primary | The cancer started at this site | C22.9 |
| Malignant Secondary | Cancer that spread (metastasized) to this site | C78.7 |
| Ca in situ | Malignant cells that have not invaded surrounding tissue | D01.5 |
| Benign | Not cancerous | D13.4 |
| Uncertain Behavior | The pathologist cannot determine whether it is benign or malignant | D37.6 |
| Unspecified Behavior | Behavior and histology are not documented | D49.0 |
Steps to Code From the Neoplasm Table
- Find the histologic term in the Alphabetic Index first. If the record says “adenoma,” look up adenoma. The Index entry tells you which column applies, for example “see also Neoplasm, by site, benign.”
- Go to the Neoplasm Table and find the site. Use the most specific site documented.
- Select the column that matches the behavior from the Index and the documentation.
- Verify the code in the Tabular List. Check for a more specific code, laterality, and instructional notes.
Only go straight to the table when no histology is documented, such as “tumor of the liver” with no further description. Note that a “mass,” unless otherwise stated, is not a neoplasm in ICD-10-CM and is not coded from the Neoplasm Table.
Uncertain Behavior vs Unspecified Behavior
These columns are easy to mix up. Uncertain behavior (D37 through D44 and D48) is used when the histology is known but the pathologist cannot tell whether the tumor is benign or malignant. Unspecified behavior (D49) is used when neither the behavior nor the histology is documented. Do not assign uncertain behavior codes without a pathology statement.
Primary and Secondary Malignancies
When cancer has spread, code both the primary site and each secondary site. Sequencing depends on what the encounter treats:
- Treatment directed at the primary site: the primary malignancy is the principal or first listed diagnosis.
- Treatment directed only at the secondary site: the secondary neoplasm is first, even though the primary is still present.
- Encounter solely for chemotherapy, immunotherapy, or radiation therapy: the Z51 code is first, followed by the neoplasm.
Example: lung cancer that has spread to the liver, with treatment aimed at the lung, is coded C34.9- for the lung (choose laterality) followed by C78.7 for the liver.
Current Cancer vs Personal History
Keep using the malignancy code while treatment is still directed at the site, including additional surgery, chemotherapy, or radiation. Once the primary has been excised or eradicated, no further treatment is directed to that site, and there is no evidence of disease there, use a code from category Z85, Personal history of malignant neoplasm. Any extension, invasion, or metastasis to another site is still coded as a secondary malignancy.
Other Neoplasm Guidelines to Know
- Overlapping sites: a primary malignancy that overlaps two or more contiguous sites goes to the .8 overlapping lesion code unless the combination is indexed elsewhere.
- Noncontiguous tumors in one organ: tumors in different quadrants of the same breast get a code for each site.
- Unknown primary: C80.1, Malignant (primary) neoplasm, unspecified, is used only when no determination can be made about the primary site and should rarely be used for inpatients.
- Anemia in malignancy: when the encounter treats only the anemia, sequence the malignancy first, followed by D63.0, Anemia in neoplastic disease.
- Benign neoplasms outside Chapter 2: some, such as prostatic adenomas, are classified in their body system chapter.
Related guides: breast cancer ICD-10 coding, primary vs secondary diagnosis, and the SEER ICD-10-CM neoplasm training. The complete rules are in Section I.C.2 of the FY2027 ICD-10-CM Official Guidelines.
Neoplasm Table FAQs
How many columns are in the Neoplasm Table?
Six code columns: Malignant Primary, Malignant Secondary, Ca in situ, Benign, Uncertain Behavior, and Unspecified Behavior.
Should I go to the Neoplasm Table first?
Only when no histology is documented. If the record names the type of tumor, look up that term in the Alphabetic Index first so you choose the right column.
Do I code the primary site when cancer has metastasized?
Yes. Code the primary and each secondary site. The focus of treatment decides which is sequenced first.
What is the difference between uncertain and unspecified behavior?
Uncertain behavior means the pathologist could not determine whether the tumor is benign or malignant. Unspecified behavior means the behavior and histology were not documented.
When do I switch from a cancer code to a history code?
When the primary has been removed or eradicated, treatment directed at that site has ended, and there is no evidence of disease at that site. Then use a Z85 code.
What code is used for cancer of unknown primary site?
C80.1, used only when the primary site cannot be determined.