ICD-10 Code B27.8 – Other infectious mononucleosis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B27.8 – Other infectious mononucleosis
What it is
B27.8 identifies infectious mononucleosis that is not classified as the common Epstein-Barr virus form. Use this code when the record documents another infectious cause or a nonspecific infectious mononucleosis diagnosis.
Clinical signs
Clinical features vary; refer to documentation. Typical mononucleosis findings may include fever, sore throat, fatigue, and lymphadenopathy, but the infectious cause should be documented when available.
When to use this code
Use B27.8 when the clinician documents infectious mononucleosis due to another specified organism, or when the chart clearly distinguishes it from EBV-related mononucleosis. It may also fit cases labeled “other infectious mononucleosis” without a more specific code. Check documentation if the cause is unclear.
Do not use for
Do not use this code for Epstein-Barr virus mononucleosis, which has its own code. Also avoid it when the record describes a different diagnosis, such as tonsillitis or pharyngitis without mononucleosis.
Coding tip
Match the code to the documented infectious cause; if the organism is named, confirm that B27.8 is the correct non-EBV mononucleosis code.