Secondary malignant neoplasm of lung

This code signifies the presence of a malignant tumor in the lung that originated from a primary cancer elsewhere in the body. It indicates that the lung is a site of metastatic disease, not the initial source of the malignancy.

Apply this code when documentation clearly states "metastatic lung cancer," "secondary lung neoplasm," or "lung metastases" from a known or unknown primary site. This code is appropriate when the lung involvement is a consequence of cancer spread, not a de novo lung cancer.

• Always sequence the primary malignant neoplasm code before this code, if known.
• Do not use this code for primary lung cancer; refer to codes in the 162.x series for primary lung malignancies.
• If the primary site is unknown, code the secondary site first, followed by a code for unknown primary site (e.g., 199.1).