ICD-10 Code B40.81 – Blastomycotic meningoencephalitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B40.81 – Blastomycotic meningoencephalitis
What it is
B40.81 identifies blastomycotic infection involving the brain and meninges. Use it for central nervous system disease caused by Blastomyces when documentation specifies meningoencephalitis.
Clinical signs
Clinical features vary; refer to documentation. Commonly, records describe neurologic symptoms with evidence of meningitis or encephalitis, such as altered mental status, headache, or focal findings.
When to use this code
Use B40.81 when the provider documents blastomycosis affecting both the meninges and brain, or explicitly states blastomycotic meningoencephalitis. It is appropriate when the CNS involvement is the confirmed diagnosis, not just a suspected infection. Check documentation if the note only mentions blastomycosis without site detail.
Do not use for
Do not use this code for uncomplicated blastomycosis, pulmonary disease, or skin involvement without CNS disease. If the record does not confirm meningoencephalitis, choose the documented site or check documentation.
Coding tip
Code the most specific blastomycosis site documented, and verify that meningoencephalitis is explicitly stated before assigning B40.81.