2026 ICD-10-CM Diagnosis Code C38.1Malignant neoplasm of anterior mediastinum

ICD-10-CM Codes›C00–D49›C30-C39›C38

ICD-10-CM C38.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C38.1 is a billable ICD-10-CM diagnosis code for malignant neoplasm of anterior mediastinum. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 180 through 182. Coders also document this condition as anterior mediastinum mass. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac cancers.

Code Identity

ICD-10-CM Code
C38.1
Billable Status
Yes — Valid for Submission
Code Describes
Malignant neoplasm of anterior mediastinum
Short Description
Malignant neoplasm of anterior mediastinum
Same as the full description in the CMS dataset.
Parent Code
C38
Malignant neoplasm of heart, mediastinum and pleura

Code Classification

ChapterC00–D49Neoplasms
SectionC30-C39Malignant neoplasms of respiratory and intrathoracic organs
CategoryC38Malignant neoplasm of heart, mediastinum and pleura
This CodeC38.1Malignant neoplasm of anterior mediastinum

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Anterior mediastinum mass
  • Malignant germ cell neoplasm of anterior mediastinum
  • Malignant germ cell neoplasm of mediastinum
  • Malignant neoplasm of anterior mediastinum
  • Neoplasm of anterior mediastinum
  • Primary malignant neoplasm of anterior mediastinum

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO011
Cardiac cancers
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.
mediastinum, mediastinal › anteriorC38.1C78.1–D15.2D38.3D49.89
substernalC38.1C78.1–D15.2D38.3D49.89

Patient EducationClinical

Cancer

Cancer is not just one disease but many diseases. Cancer begins in your cells, which are the building blocks of your body. Usually, your body forms new cells as needed, replacing old cells that die. Sometimes this process goes wrong. New cells grow even when you don't need them, and old cells don't die when they should.

The full article covers:

  • What is cancer?
  • What are the types of cancer?
  • How does cancer develop?
  • What are the symptoms of cancer?
  • How is cancer diagnosed?
  • What are the treatments for cancer?
  • Can cancer be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert C38.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
164.2 Mal neo ant mediastinum
Exact Match The mapping is direct, with no qualifiers.

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 C38.1Overview

Is C38.1 (Malignant neoplasm of heart, mediastinum and pleura) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of anterior mediastinum on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does C38.1 group to?

When malignant neoplasm of anterior mediastinum is the principal diagnosis on an inpatient stay, it groups to MS-DRG 180, 181, 182, with relative weights from 0.7440 to 1.7660 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of C38.1?

Under the General Equivalence Mappings, malignant neoplasm of anterior mediastinum converts to ICD-9-CM 164.2 (mal neo ant mediastinum). The mapping is a direct match.

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.