ICD-10 Code B40 – Blastomycosis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B40 – Blastomycosis
What it is
Blastomycosis is a fungal infection caused by Blastomyces species. It usually affects the lungs first and may spread to the skin, bones, or other organs.
Clinical signs
Clinical features vary; refer to documentation. Common findings include cough, fever, chest pain, and shortness of breath, with possible skin lesions or disseminated disease in more severe cases.
When to use this code
Use B40 when the provider documents blastomycosis or blastomycotic infection. This code fits confirmed cases involving pulmonary disease or infection that has spread beyond the lungs. Check documentation for the site and extent when recorded.
Do not use for
Do not use this code for other fungal infections, such as histoplasmosis or coccidioidomycosis. If the record only says “fungal infection” without blastomycosis, check documentation.
Coding tip
Assign the most specific B40 subcode available, and verify whether the infection is pulmonary, cutaneous, or disseminated.