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ICD-10-CM 2027 diagnosis code

C01Malignant neoplasm of base of tongue

✓ Billable / specific

C01 is a valid, billable ICD-10-CM code for malignant neoplasm of base of tongue. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About C01

C01 is the ICD-10-CM diagnosis code for malignant neoplasm of base of tongue. It belongs to block C00-C14 (malignant neoplasms of lip, oral cavity and pharynx) and chapter 2 (neoplasms). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Use an additional code to identify: alcohol abuse and dependence (F10.-), history of tobacco dependence (Z87.891), tobacco dependence (F17.-) and tobacco use (Z72.0).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 011 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with MCC, relative weight 5.6154), DRG 012 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with CC, relative weight 4.381), DRG 013 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy without CC/MCC, relative weight 2.7307), DRG 146 (Ear, Nose, Mouth and Throat Malignancy with MCC, relative weight 2.1329), DRG 147 (Ear, Nose, Mouth and Throat Malignancy with CC, relative weight 1.3055) and DRG 148 (Ear, Nose, Mouth and Throat Malignancy without CC/MCC, relative weight 0.8008), in Pre-MDC and MDC 03 (Diseases and Disorders of the Ear, Nose, Mouth and Throat), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 141.0 (malignant neoplasm of base of tongue).

Coding notes

Applicable toConditions and synonyms classified to this code
  • Malignant neoplasm of dorsal surface of base of tongue
  • Malignant neoplasm of fixed part of tongue NOS
  • Malignant neoplasm of posterior third of tongue
Use additional codeAdd a secondary code to fully describe the condition
  • code to identify:
  • alcohol abuse and dependence (F10.-)
  • history of tobacco dependence (Z87.891)
  • tobacco dependence (F17.-)
  • tobacco use (Z72.0)

Notes that apply from higher levels

Instructions written at a parent level also apply to C01.

Broader instructions also apply from Chapter 2: Neoplasms.

Table of Drugs & Neoplasms entries

Codes whose notes reference C01

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 141.0Malignant neoplasm of base of tongueexact

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about C01

Is C01 billable?

Yes. C01 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can C01 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict C01 as a principal diagnosis.

Is C01 a CC or MCC?

No. C01 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does C01 group to?

C01 is used in the MS-DRG v44.0 logic for MS-DRG 011 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with MCC), MS-DRG 012 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with CC), MS-DRG 013 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy without CC/MCC), MS-DRG 146 (Ear, Nose, Mouth and Throat Malignancy with MCC), MS-DRG 147 (Ear, Nose, Mouth and Throat Malignancy with CC) and MS-DRG 148 (Ear, Nose, Mouth and Throat Malignancy without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for C01?

The CMS General Equivalence Mappings map C01 to ICD-9-CM 141.0.