FY2027
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ICD-10 Code for Infectious Mononucleosis

The ICD-10-CM code for infectious Mononucleosis is B27.90 — Infectious mononucleosis, unspecified without complication. This is the code the Alphabetic Index gives for infectious Mononucleosis with no further qualifier, valid for FY2027 (October 1, 2026 – September 30, 2027).

BillableUnspecified

B27.90 is billable but unspecified. If the documentation names a type, site or cause, one of the more specific codes below is likely expected.

Which infectious Mononucleosis code should you use?

The Alphabetic Index lists 16 codes under Mononucleosis, infectious. Which one applies depends on the qualifier documented in the record — the type, site, cause, or associated condition. Find the qualifier below, then verify the code in the Tabular List before using it.

By type

cytomegaloviralB27.10Cytomegaloviral mononucleosis without complications
Epstein-BarrB27.00Gammaherpesviral mononucleosis without complication
gammaherpesviralB27.00Gammaherpesviral mononucleosis without complication
specified NECB27.80Other infectious mononucleosis without complication

Infectious Mononucleosis with

complication NECB27.99Infectious mononucleosis, unspecified with other complication
meningitisB27.92Infectious mononucleosis, unspecified with meningitis
polyneuropathyB27.91Infectious mononucleosis, unspecified with polyneuropathy

Infectious Mononucleosis cytomegaloviral

with › complication NECB27.19Cytomegaloviral mononucleosis with other complication
with › meningitisB27.12Cytomegaloviral mononucleosis with meningitis
with › polyneuropathyB27.11Cytomegaloviral mononucleosis with polyneuropathy

Infectious Mononucleosis Epstein-Barr

with › complication NECB27.09Gammaherpesviral mononucleosis with other complications
with › meningitisB27.02Gammaherpesviral mononucleosis with meningitis
with › polyneuropathyB27.01Gammaherpesviral mononucleosis with polyneuropathy

Infectious Mononucleosis gammaherpesviral

with › complication NECB27.09Gammaherpesviral mononucleosis with other complications
with › meningitisB27.02Gammaherpesviral mononucleosis with meningitis
with › polyneuropathyB27.01Gammaherpesviral mononucleosis with polyneuropathy

Infectious Mononucleosis specified NEC

with › complication NECB27.89Other infectious mononucleosis with other complication
with › meningitisB27.82Other infectious mononucleosis with meningitis
with › polyneuropathyB27.81Other infectious mononucleosis with polyneuropathy

Index terms and codes are reproduced from the official ICD-10-CM FY2027 release. The Alphabetic Index is a finding aid — a code must always be verified in the Tabular List before it is reported. Data sources