2026 ICD-10-CM Diagnosis Code C09.8Malignant neoplasm of overlapping sites of tonsil

ICD-10-CM Codes›C00–D49›C00-C14›C09

ICD-10-CM C09.8
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

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 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.

Code Identity

ICD-10-CM Code
C09.8
Billable Status
Yes — Valid for Submission
Code Describes
Malignant neoplasm of overlapping sites of tonsil
Short Description
Malignant neoplasm of overlapping sites of tonsil
Same as the full description in the CMS dataset.
Parent Code
C09
Malignant neoplasm of tonsil

Code Classification

ChapterC00–D49Neoplasms
SectionC00-C14Malignant neoplasms of lip, oral cavity and pharynx
CategoryC09Malignant neoplasm of tonsil
This CodeC09.8Malignant neoplasm of overlapping sites of tonsil

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.

CCSR NEO009
Head and neck cancers - tonsils
Default principal diagnosis: inpatient Yes · outpatient Yes

Table of NeoplasmsClinical

Anatomical sites in the Table of Neoplasms that reference this code family.

SiteMalig.
Primary		Malig.
Secondary		Ca
in situ		BenignUncertainUnspec.
tonsil › overlapping sitesC09.8–––––

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.

ICD-9-CM
146.0 Malignant neopl tonsil
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About C09.8Overview

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 146, 147, 148, with relative weights from 0.7971 to 2.1174 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.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.