B27 — Infectious mononucleosis
Is B27 billable?
No — B27 is a non-billable header code. B27 groups more specific codes and cannot be submitted on a claim. A valid ICD-10-CM code must be reported at the highest level of specificity available in its branch. Select one of the 16 billable codes beneath B27.
Billable codes under this header
- B27.00Gammaherpesviral mononucleosis without complication
- B27.01Gammaherpesviral mononucleosis with polyneuropathy
- B27.02Gammaherpesviral mononucleosis with meningitis
- B27.09Gammaherpesviral mononucleosis with other complications
- B27.10Cytomegaloviral mononucleosis without complications
- B27.11Cytomegaloviral mononucleosis with polyneuropathy
- B27.12Cytomegaloviral mononucleosis with meningitis
- B27.19Cytomegaloviral mononucleosis with other complication
- B27.80Other infectious mononucleosis without complication
- B27.81Other infectious mononucleosis with polyneuropathy
- B27.82Other infectious mononucleosis with meningitis
- B27.89Other infectious mononucleosis with other complication
- B27.90Infectious mononucleosis, unspecified without complication
- B27.91Infectious mononucleosis, unspecified with polyneuropathy
- B27.92Infectious mononucleosis, unspecified with meningitis
- B27.99Infectious mononucleosis, unspecified with other complication
B27 at a glance
| Code | B27 |
|---|---|
| Description | Infectious mononucleosis |
| Billable | No — header code |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Includes
Conditions classified to B27.
- glandular fever
- monocytic angina
- Pfeiffer's disease
Use additional code — inherited from Chapter 1
Report an additional code alongside B27 to fully describe the condition. B27 is sequenced first.
- code to identify resistance to antimicrobial drugs (Z16.-)
Excludes2 — not included here — inherited from Chapter 1
The conditions below are not part of B27, but a patient may have both at the same time. When documentation supports it, B27 and the excluded code may both be reported.
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
What codes fall under B27? (4)
How long has B27 existed?
B27 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.
Which codes are confused with B27?
ICD-10-CM declares these codes mutually exclusive with B27 — exactly one of each pair can be correct for a given encounter.