2026 ICD-10-CM Diagnosis Code C78.00Secondary malignant neoplasm of unspecified lung
ICD-10-CM Codes›C00–D49›C76-C80›C78
- Billable — Valid for Submission
- Chronic Condition
C78.00 is a billable ICD-10-CM diagnosis code for secondary malignant neoplasm of unspecified 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
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Hilar mass
- Main bronchus involved by direct extension of malignant neoplasm
- Malignant neoplasm of carina of trachea
- Metastatic carcinoma to lower lobe of lung
- Metastatic carcinoma to main bronchus
- Metastatic giant cell carcinoma to lung
- Metastatic large cell carcinoma to lung
- Metastatic malignant neoplasm to bronchus
- Metastatic malignant neoplasm to carina
- Metastatic malignant neoplasm to hilus of lung
- Metastatic malignant neoplasm to lung
- Metastatic malignant neoplasm to main bronchus
- Metastatic malignant neoplasm to trachea
- Metastatic non-small cell lung cancer
- Metastatic squamous cell carcinoma to bronchus
- Metastatic squamous cell carcinoma to lung
- Metastatic undifferentiated large cell carcinoma to lung
- Metastatic well-differentiated neuroendocrine tumor
- Metastatic well-differentiated neuroendocrine tumor to lung
- Neoplasm of carina
- Neoplasm of hilus of lung
- Neoplasm of lower respiratory tract and mediastinum
- Tumor invasion into lung parenchyma
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. |
|---|---|---|---|---|---|---|
| bronchiogenic, bronchogenic (lung) | C34.9 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| bronchiole | C34.9 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| bronchus | C34.9 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| bronchus › carina | C34.0 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| bronchus › lower lobe of lung | C34.3 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| bronchus › main | C34.0 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| bronchus › middle lobe of lung | C34.2 | C78.0 | D02.21 | D14.31 | D38.1 | D49.1 |
| bronchus › upper lobe of lung | C34.1 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| carina (bronchus) | C34.0 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| hilus of lung | C34.0 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| lingula, lung | C34.1 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| lung | C34.9 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| lung › azygos lobe | C34.1 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| lung › carina | C34.0 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| lung › hilus | C34.0 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| lung › lingula | C34.1 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| lung › lobe NEC | C34.9 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| lung › lower lobe | C34.3 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| lung › main bronchus | C34.0 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| lung › middle lobe | C34.2 | C78.0 | D02.21 | D14.31 | D38.1 | D49.1 |
| lung › upper lobe | C34.1 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| pulmonary [See Also: Neoplasm, lung] | C34.9 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
| subpleural | C34.9 | C78.0 | D02.2 | D14.3 | D38.1 | D49.1 |
Patient EducationClinical
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Convert C78.00 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C78.00Overview
Is C78.00 (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 unspecified lung on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does C78.00 group to?
When secondary malignant neoplasm of unspecified 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 C78.00?
Under the General Equivalence Mappings, secondary malignant neoplasm of unspecified 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.
