ICD-10-CM 2027 diagnosis code

B27.8Other infectious mononucleosis

Not billable — use a more specific code

B27.8 is a header code, so it can't be reported by itself. Choose one of the 4 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About B27.8

B27.8 is the ICD-10-CM diagnosis code for other infectious mononucleosis. It belongs to category B27 (infectious mononucleosis), block B25-B34 (other viral diseases) and chapter 1 (certain infectious and parasitic diseases). It is a header code, so it can't be reported by itself; one of its 4 subcodes must be used instead.

Within B27, choose B27.8 (Other infectious mononucleosis) only when documentation doesn't support a more specific option: Gammaherpesviral mononucleosis (B27.0), cytomegaloviral mononucleosis (B27.1) and unspecified (B27.9).

To report this condition, pick the subcode that matches the documentation: B27.80 (without complication), B27.81 (with polyneuropathy), B27.82 (with meningitis) and B27.89 (with other complication).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under B27.8

Notes that apply from higher levels

Instructions written at a parent level also apply to B27.8.

› From B27 Infectious mononucleosis

Includes

glandular fever
monocytic angina
Pfeiffer's disease

Broader instructions also apply from Chapter 1: Certain infectious and parasitic diseases.

Code history

2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027

FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
No changes since FY2016.

Common questions about B27.8

Is B27.8 billable?: No. B27.8 is a header code. Report one of its more specific subcodes instead.