2026 ICD-10-CM Diagnosis Code C78.02Secondary malignant neoplasm of left lung

ICD-10-CM Codes›C00–D49›C76-C80›C78

ICD-10-CM C78.02
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C78.02 is a billable ICD-10-CM diagnosis code for secondary malignant neoplasm of left lung. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Secondary malignancies.

Code Identity

ICD-10-CM Code
C78.02
Billable Status
Yes — Valid for Submission
Code Describes
Secondary malignant neoplasm of left lung
Short Description
Secondary malignant neoplasm of left lung
Same as the full description in the CMS dataset.
Parent Code
C78.0
Secondary malignant neoplasm of lung

Code Classification

ChapterC00–D49Neoplasms
SectionC76-C80Malignant neoplasms of ill-defined, other secondary and unspecified sites
CategoryC78Secondary malignant neoplasm of respiratory and digestive organs
This CodeC78.02Secondary malignant neoplasm of left lung

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adenocarcinoma of left lung
  • Adenocarcinoma of right lung
  • Bilateral metastatic giant cell carcinoma to lungs
  • Bilateral metastatic large cell carcinoma to lungs
  • Bilateral metastatic small cell carcinoma to lungs
  • Malignant carcinoid tumor of left lung
  • Malignant neoplasm of lower lobe bronchus
  • Malignant neoplasm of upper lobe bronchus
  • Metastatic adenocarcinoma to bilateral lungs
  • Metastatic adenocarcinoma to left lung
  • Metastatic adenocarcinoma to right lung
  • Metastatic giant cell carcinoma to left lung
  • Metastatic giant cell carcinoma to lung
  • Metastatic giant cell carcinoma to right lung
  • Metastatic large cell carcinoma to left lung
  • Metastatic large cell carcinoma to lung
  • Metastatic large cell carcinoma to right lung
  • Metastatic malignant neoplasm to bilateral lungs
  • Metastatic malignant neoplasm to bronchus of left lower lobe
  • Metastatic malignant neoplasm to bronchus of left upper lobe
  • Metastatic malignant neoplasm to left lower lobe of lung
  • Metastatic malignant neoplasm to left lung
  • Metastatic malignant neoplasm to left upper lobe of lung
  • Metastatic small cell carcinoma to left lung
  • Metastatic small cell carcinoma to right lung
  • Metastatic small cell neuroendocrine carcinoma
  • Metastatic squamous cell carcinoma to bilateral lungs
  • Metastatic squamous cell carcinoma to bronchus
  • Metastatic squamous cell carcinoma to bronchus of left lower lobe
  • Metastatic squamous cell carcinoma to bronchus of left upper lobe
  • Metastatic squamous cell carcinoma to left lung
  • Metastatic squamous cell carcinoma to lung
  • Metastatic squamous cell carcinoma to right lung
  • Metastatic well-differentiated neuroendocrine tumor
  • Metastatic well-differentiated neuroendocrine tumor to left lung
  • Metastatic well-differentiated neuroendocrine tumor to lung
  • Neoplasm of bronchus of left lower lobe
  • Neoplasm of bronchus of left upper lobe
  • Squamous cell carcinoma of bronchus in left lower lobe
  • Squamous cell carcinoma of bronchus in left upper lobe

Clinical ClassificationClinical

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

CCSR NEO070
Secondary malignancies
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.
bronchiogenic, bronchogenic (lung)C34.9C78.0D02.2D14.3D38.1D49.1
bronchioleC34.9C78.0D02.2D14.3D38.1D49.1
bronchusC34.9C78.0D02.2D14.3D38.1D49.1
bronchus › carinaC34.0C78.0D02.2D14.3D38.1D49.1
bronchus › lower lobe of lungC34.3C78.0D02.2D14.3D38.1D49.1
bronchus › mainC34.0C78.0D02.2D14.3D38.1D49.1
bronchus › middle lobe of lungC34.2C78.0D02.21D14.31D38.1D49.1
bronchus › upper lobe of lungC34.1C78.0D02.2D14.3D38.1D49.1
carina (bronchus)C34.0C78.0D02.2D14.3D38.1D49.1
hilus of lungC34.0C78.0D02.2D14.3D38.1D49.1
lingula, lungC34.1C78.0D02.2D14.3D38.1D49.1
lungC34.9C78.0D02.2D14.3D38.1D49.1
lung › azygos lobeC34.1C78.0D02.2D14.3D38.1D49.1
lung › carinaC34.0C78.0D02.2D14.3D38.1D49.1
lung › hilusC34.0C78.0D02.2D14.3D38.1D49.1
lung › lingulaC34.1C78.0D02.2D14.3D38.1D49.1
lung › lobe NECC34.9C78.0D02.2D14.3D38.1D49.1
lung › lower lobeC34.3C78.0D02.2D14.3D38.1D49.1
lung › main bronchusC34.0C78.0D02.2D14.3D38.1D49.1
lung › middle lobeC34.2C78.0D02.21D14.31D38.1D49.1
lung › upper lobeC34.1C78.0D02.2D14.3D38.1D49.1
pulmonary [See Also: Neoplasm, lung]C34.9C78.0D02.2D14.3D38.1D49.1
subpleuralC34.9C78.0D02.2D14.3D38.1D49.1

Patient EducationClinical

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Convert C78.02 to ICD-9-CMHistory

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

ICD-9-CM
197.0 Secondary malig neo lung
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 C78.02Overview

Is C78.02 (Secondary malignant neoplasm of lung) a billable code?

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

What MS-DRG does C78.02 group to?

When secondary malignant neoplasm of left lung 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 C78.02?

Under the General Equivalence Mappings, secondary malignant neoplasm of left lung converts to ICD-9-CM 197.0 (secondary malig neo lung). 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.