ICD-10 Code B26.2 – Mumps Encephalitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B26.2 – Mumps encephalitis
What it is
B26.2 identifies encephalitis caused by mumps infection. Use it when the record documents central nervous system inflammation as a complication of mumps.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include fever, headache, altered mental status, seizures, or other neurologic signs consistent with encephalitis.
When to use this code
Use this code when the provider documents mumps encephalitis, mumps with encephalitis, or encephalitic involvement linked to a confirmed mumps infection. It is appropriate for inpatient, emergency, or follow-up records if the encephalitis is still being addressed. Check documentation if the neurologic diagnosis is uncertain.
Do not use for
Do not use B26.2 for uncomplicated mumps or for neurologic symptoms without documented encephalitis. Do not assign it when another cause of encephalitis is identified.
Coding tip
Verify that the chart explicitly connects encephalitis to mumps before reporting B26.2.