ICD-10 Code B27.10 – Cytomegaloviral mononucleosis without complications (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B27.10 – Cytomegaloviral mononucleosis without complications
What it is
B27.10 identifies mononucleosis caused by cytomegalovirus, with no documented complications. Use it when the record shows CMV infection presenting as a mono-like illness, but not a more severe or separate condition.
Clinical signs
Typical findings may include fever, fatigue, malaise, sore throat, and lymphadenopathy. Clinical features vary; refer to documentation, especially when CMV is confirmed or strongly suspected as the cause.
When to use this code
Use this code when the provider documents cytomegaloviral mononucleosis and explicitly states there are no complications. It fits cases described as CMV mononucleosis, mono-like syndrome, or infectious mononucleosis due to CMV. If the note also describes organ involvement or another complication, check documentation for a different code.
Do not use for
Do not use B27.10 for unspecified mononucleosis, EBV mononucleosis, or CMV infection without a mononucleosis diagnosis. If complications are documented, this code is not appropriate.
Coding tip
Code from the provider’s documented cause and complication status, and query if the record only says “mono” or “CMV infection.”