ICD-10 Code A42.8 – Other forms of actinomycosis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A42.8 – Other forms of actinomycosis
What it is
A42.8 identifies actinomycosis that does not fit the other specified categories. It is a chronic bacterial infection caused by Actinomyces species, often involving deeper tissues and forming slowly progressive lesions.
Clinical signs
Clinical features vary; refer to documentation. Common findings include indurated swelling, draining sinus tracts, abscesses, and granulomatous infection in affected tissues.
When to use this code
Use A42.8 when the provider documents actinomycosis, but the site or presentation is not described by another more specific A42 code. This may include atypical or mixed-site disease. If the record names a different actinomycosis form, code that more specific diagnosis instead.
Do not use for
Do not use this code for unspecified bacterial abscesses or infections without documented actinomycosis. If documentation supports a more specific actinomycosis site or form, choose that code instead.
Coding tip
Check the provider’s exact wording for site and form details before defaulting to A42.8.