ICD-10 Code A43.0 – Pulmonary nocardiosis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A43.0 – Pulmonary nocardiosis
What it is
A43.0 identifies nocardial infection involving the lungs. Use it when documentation specifies pulmonary nocardiosis or nocardial pneumonia affecting the respiratory tract.
Clinical signs
Clinical features vary; refer to documentation. Reported findings may include cough, fever, chest pain, shortness of breath, and pulmonary infiltrates, but you should code only when the diagnosis is confirmed.
When to use this code
Use A43.0 when the provider documents pulmonary nocardiosis, nocardial lung infection, or nocardial pneumonia. It fits cases where the infection is limited to the lungs or the lung is the primary site mentioned. If the record only says nocardiosis without site, check documentation before assigning this code.
Do not use for
Do not use this code for nonpulmonary nocardiosis, such as cutaneous or disseminated disease, unless the lung involvement is clearly documented. Do not code it for suspected infection or for nonspecific pneumonia without a nocardia diagnosis.
Coding tip
Verify the anatomic site in the note; A43.0 is site-specific, so “nocardiosis” alone is not enough.