ICD-10 Code B46.9 – Zygomycosis, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B46.9 – Zygomycosis, unspecified
What it is
B46.9 identifies zygomycosis, also called mucormycosis, when the site or specific form is not documented. Use it for an invasive fungal infection caused by molds in the order Mucorales.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include rapidly progressive tissue infection, necrosis, sinus or pulmonary involvement, and signs of invasive fungal disease in high-risk patients.
When to use this code
Use B46.9 when the provider documents zygomycosis or mucormycosis but does not specify the anatomic site or subtype. It also fits when notes confirm invasive disease and no more specific B46 category is supported. Check documentation if the record only says “fungal infection.”
Do not use for
Do not use this code for other fungal infections, such as candidiasis or aspergillosis. Avoid it when the record names a specific zygomycosis site or form that has a more precise ICD-10-CM code.
Coding tip
Query for the site and organism documentation before defaulting to B46.9.