Chapter 2: Neoplasms (C00-D49)
General Guidelines Chapter 2 of the ICD-10-CM contains the codes for most benign and all malignant neoplasms. Certain benign neoplasms, such as prostatic adenomas, may be found in the specific body system chapters. To properly code a neoplasm, it is necessary to determine from the record if the neoplasm is benign, in-situ, malignant, or of uncertain histologic behavior.
If malignant, any secondary (metastatic) sites should also be determined. Primary malignant neoplasms overlapping site boundaries 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.
For multiple neoplasms of the same site that are not contiguous such as tumors in different quadrants of the same breast, codes for each site should be assigned. Malignant neoplasm of ectopic tissue Malignant neoplasms of ectopic tissue are to be coded to the site of origin mentioned, e.g., ectopic pancreatic malignant neoplasms involving the stomach are coded to malignant neoplasm of pancreas, unspecified (C25.9).
The neoplasm table in the Alphabetic Index should be referenced first. However, if the histological term is documented, that term should be referenced first, rather than going immediately to the Neoplasm Table, in order to determine which column in the Neoplasm Table is appropriate.
For example, if the documentation indicates “adenoma,” refer to the term in the Alphabetic Index to review the entries under this term and the instructional note to “see also neoplasm, by site, benign.” The table provides the proper code based on the type of neoplasm and the site. It is important to select the proper column in the table that corresponds to the type of neoplasm.
The Tabular List should then be referenced to verify that the correct code has been selected from the table and that a more specific site code does not exist. See Section I.C.21. Factors influencing health status and contact with health services, Status, for information regarding Z15.0, codes for genetic susceptibility to cancer.
In this section
- I.C.2.aAdmission/Encounter for treatment of primary site
- I.C.2.bAdmission/Encounter for treatment of secondary site
- I.C.2.cCoding and sequencing of complications
- I.C.2.dPrimary malignancy previously excised
- I.C.2.eAdmissions/Encounters involving antineoplastic chemotherapy, immunotherapy and radiation therapy
- I.C.2.fAdmission/encounter to determine extent of malignancy
- I.C.2.gSymptoms, signs, and abnormal findings listed in Chapter 18 associated with neoplasms
- I.C.2.hAdmission/encounter for pain control/management
- I.C.2.iMalignancy in two or more noncontiguous sites
- I.C.2.jDisseminated malignant neoplasm, unspecified
- I.C.2.kMalignant neoplasm without specification of site
- I.C.2.lSequencing of neoplasm codes
- I.C.2.mCurrent malignancy versus personal history of malignancy
- I.C.2.nLeukemia, Multiple Myeloma, and Malignant Plasma Cell
- I.C.2.oAftercare following surgery for neoplasm
- I.C.2.pFollow-up care for completed treatment of a malignancy
- I.C.2.qProphylactic organ removal for prevention of malignancy
- I.C.2.rMalignant neoplasm associated with transplanted organ
- I.C.2.sBreast Implant Associated Anaplastic Large Cell Lymphoma
- I.C.2.tSecondary malignant neoplasm of lymphoid tissue
ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026 (effective October 1, 2025). Published by CMS and NCHS. Reproduced for reference — always verify against the official CMS release.