ICD-10 Code C78.30 – Secondary malignant neoplasm of unspecified respiratory organ (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C78.30 – Secondary malignant neoplasm of unspecified respiratory organ
What it is
This code identifies metastatic cancer involving a respiratory organ, but the exact site is not named in the record. Use it when documentation confirms secondary malignant disease in the respiratory system without further detail.
Clinical signs
Clinical features vary; refer to documentation. Findings may include evidence of metastatic disease affecting a lung or other respiratory structure, usually confirmed by imaging, pathology, or specialist assessment.
When to use this code
Use C78.30 when the provider documents secondary malignant neoplasm of a respiratory organ and does not specify which organ. It is appropriate for encounter notes, discharge summaries, or pathology reports that support metastatic involvement. If the site is later identified, code the more specific location instead.
Do not use for
Do not use this code for primary respiratory cancers or for metastases to non-respiratory organs. If the documentation names a specific respiratory site, check documentation for a more precise code.
Coding tip
Query the provider when the respiratory site is unclear, because unspecified metastatic codes should be used only when no more detail is available.