2026 ICD-10-CM Diagnosis Code C09.8Malignant neoplasm of overlapping sites of tonsil
ICD-10-CM Codes›C00–D49›C00-C14›C09
- Billable — Valid for Submission
- Risk Adjusts — HCC 21
- Chronic Condition
C09.8 is a billable ICD-10-CM diagnosis code for malignant neoplasm of overlapping sites of tonsil. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 11 through 13, 146 through 148. Coders also document this condition as malignant neoplasm of tonsil. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Head and neck cancers - tonsils.
For Medicare Advantage risk adjustment, C09.8 maps to CMS-HCC Category 21 (Lymphoma and Other Cancers) under the V28 model, adding a risk factor of about 0.671 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C09.8 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Malignant neoplasm of tonsil
- Overlapping malignant neoplasm of oropharynx
- Overlapping malignant neoplasm of tonsil
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Table of NeoplasmsClinical
Anatomical sites in the Table of Neoplasms that reference this code family.
| Site | Malig. Primary | Malig. Secondary | Ca in situ | Benign | Uncertain | Unspec. |
|---|---|---|---|---|---|---|
| tonsil › overlapping sites | C09.8 | – | – | – | – | – |
Patient EducationClinical
Throat Cancer
Throat cancer is a type of head and neck cancer. Throat cancer has different names, depending on which part of the throat is affected. The different parts of your throat are called the oropharynx, the hypopharynx, the nasopharynx, and the larynx, or voice box.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C09.8 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C09.8Overview
What is the ICD-10 code for malignant neoplasm of overlapping sites of tonsil?
The ICD-10-CM code for malignant neoplasm of overlapping sites of tonsil is C09.8 (sometimes written as C098). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is C09.8 (Malignant neoplasm of tonsil) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of overlapping sites of tonsil on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does C09.8 group to?
When malignant neoplasm of overlapping sites of tonsil is the principal diagnosis on an inpatient stay, it groups to MS-DRG 11, 12, 13, 146, 147, 148, with relative weights from 0.7971 to 5.4541 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of C09.8?
Under the General Equivalence Mappings, malignant neoplasm of overlapping sites of tonsil converts to ICD-9-CM 146.0 (malignant neopl tonsil). The mapping is approximate, so confirm the match fits the documentation.
What HCC is C09.8?
C09.8 (malignant neoplasm of overlapping sites of tonsil) maps to CMS-HCC Category 21 (Lymphoma and Other Cancers), commonly written as HCC 21, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 11 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does C09.8 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C09.8 adds a risk adjustment factor of about 0.671 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.493 to 0.739 depending on the payment segment). A more severe related category (HCC 17, HCC 18, HCC 19, and HCC 20) supersedes it when both are reported. See the full factor table on the HCC 21 category page.
