Secondary malignant neoplasm of unspecified lung

This code signifies the presence of a metastatic cancerous tumor in the lung, where the primary cancer originated elsewhere in the body. It indicates that the specific lobe or region of the lung affected by the secondary malignancy is not documented or is unknown. This is a common finding in advanced stages of various primary cancers.

Use this code when documentation clearly states "secondary malignant neoplasm of lung, unspecified" or "metastatic cancer to lung, site unspecified." It is appropriate when the primary site of the cancer is known and coded separately, or when the primary site is unknown. Supporting documentation includes pathology reports, imaging studies (CT, MRI, PET scans), and physician notes confirming lung metastasis without further anatomical specificity.

• Always code the primary malignancy first, if known, followed by this code for the secondary site.
• Avoid using this code if the specific lobe (e.g., upper lobe, lower lobe) of the lung metastasis is documented; instead, use a more specific C78.0- code.
• Do not confuse with primary lung cancer (C34.-) or carcinoma in situ of lung (D02.2).