Lung involvement in other diseases classified elsewhere

This code signifies pulmonary manifestations that arise as a secondary complication or feature of another primary systemic disease. It indicates that the lungs are affected by a condition originating elsewhere in the body, rather than being the primary site of the disease. This can include various forms of lung pathology, such as interstitial lung disease, effusions, or infiltrates, directly attributable to an underlying systemic illness.

Use this code when documentation clearly links lung involvement to a primary disease classified elsewhere, such as connective tissue disorders, certain infectious diseases, or systemic vasculitides. It is appropriate when the lung condition is not a standalone diagnosis but a direct consequence or complication of another principal diagnosis. The medical record should explicitly state the causal relationship between the systemic disease and the pulmonary findings.

• Always sequence the underlying systemic disease first, as this code is a manifestation code.
• Ensure the documentation specifies the "other disease" that is causing the lung involvement; avoid using this code without a clear primary diagnosis.
• Do not use for primary lung diseases or infections where the lung is the initial site of pathology.