ICD-10 Code A50.42 – Late congenital syphilitic encephalitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A50.42 – Late congenital syphilitic encephalitis
What it is
A50.42 identifies late congenital syphilitic encephalitis, a neurologic complication of congenital syphilis that appears later in childhood. It indicates brain involvement from untreated or inadequately treated maternal infection.
Clinical signs
Clinical features vary; refer to documentation. You may see neurologic impairment, developmental delay, seizures, or other signs of central nervous system involvement in a child with confirmed congenital syphilis.
When to use this code
Use this code when the provider documents late congenital syphilitic encephalitis as the diagnosis. It fits cases where congenital syphilis has progressed and the encephalitic manifestation is specifically identified. If the record only says congenital syphilis without neurologic involvement, check documentation.
Do not use for
Do not use A50.42 for acquired syphilis, nonspecific encephalopathy, or congenital syphilis without encephalitis. If the chart does not clearly link the neurologic findings to congenital syphilis, you should not assume this code.
Coding tip
Confirm that the provider documents both congenital syphilis and late encephalitic involvement before assigning A50.42.