ICD-10 Code B27.19 – Cytomegaloviral mononucleosis with other complication (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B27.19 – Cytomegaloviral mononucleosis with other complication
What it is
B27.19 identifies mononucleosis caused by cytomegalovirus with a documented complication beyond the usual illness. Use it when the record clearly links CMV infection to the mononucleosis syndrome and an additional complication.
Clinical signs
Typical findings may include fever, fatigue, malaise, and lymphadenopathy, with a mononucleosis-like presentation. Clinical features vary; refer to documentation for the specific complication and confirm CMV as the cause.
When to use this code
Use this code when the provider documents CMV mononucleosis and also names another complication, such as organ involvement or a related sequela. Apply it only when the complication is clearly stated in the assessment or discharge diagnosis. If the note is nonspecific, check documentation.
Do not use for
Do not use B27.19 for uncomplicated cytomegaloviral mononucleosis or for mononucleosis caused by another organism. Do not assign it when CMV is mentioned without a documented complication.
Coding tip
Code the complication only when the chart explicitly connects it to CMV mononucleosis.