2027 ICD-10-CM Diagnosis Code B27.01Gammaherpesviral mononucleosis with polyneuropathy

ICD-10-CM Codes›A00–B99›B25-B34›B27

ICD-10-CM B27.01
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

B27.01 is a billable ICD-10-CM diagnosis code for gammaherpesviral mononucleosis with polyneuropathy. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 865 through 866. Coders also document this condition as polyneuropathy due to gammaherpesviral mononucleosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (neither hereditary nor degenerative), Polyneuropathies, and Viral infection.

Code Identity

ICD-10-CM Code
B27.01
Billable Status
Yes — Valid for Submission
Code Describes
Gammaherpesviral mononucleosis with polyneuropathy
Short Description
Gammaherpesviral mononucleosis with polyneuropathy
Same as the full description in the CMS dataset.
Parent Code
B27.0
Gammaherpesviral mononucleosis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB25-B34Other viral diseases
CategoryB27Infectious mononucleosis
This CodeB27.01Gammaherpesviral mononucleosis with polyneuropathy

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Polyneuropathy due to gammaherpesviral mononucleosis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to B27.01: its own notes plus those printed at B27 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From B27 Infectious mononucleosis applies to 16 codes
  • glandular fever
  • monocytic angina
  • Pfeiffer's disease
From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • 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)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • code to identify resistance to antimicrobial drugs (Z16.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name B27.01, its category, or a range that includes it.

Applicable To 1

These notes mention B27.01.

  • O98.5 Other viral diseases complicating pregnancy, childbirth and the puerperium
    Conditions in A80-B09, B25-B34, R87.81-, R87.82- names B25-B34, which includes this code

Excludes1 4

These codes carry an Excludes1 note naming B27.01: they are not reported together with it, unless the two conditions are unrelated.

  • D72.821 Monocytosis (symptomatic)
    infectious mononucleosis (B27.-) names B27.-, which includes this code
  • G02 Meningitis in other infectious and parasitic diseases classified elsewhere
    infectious mononucleosis complicated by meningitis (B27.- with fifth character 2) names B27.-, which includes this code
  • J02.8 Acute pharyngitis due to other specified organisms
    acute pharyngitis due to infectious mononucleosis (B27.-) names B27.-, which includes this code
  • G63 Polyneuropathy in diseases classified elsewhere
    infectious mononucleosis complicated by polyneuropathy (B27.0-B27.9 with fifth character 1) names B27.0-B27.9, which includes this code

Excludes2 3

These codes carry an Excludes2 note naming B27.01: its condition is not part of those codes, and both may be reported when the patient has both.

  • B00 Herpesviral [herpes simplex] infections
    gammaherpesviral mononucleosis (B27.0-) names B27.0-, which includes this code
  • B10 Other human herpesviruses
    Epstein-Barr virus (B27.0-) names B27.0-, which includes this code
  • B10 Other human herpesviruses
    human herpesvirus 4 (B27.0-) names B27.0-, which includes this code

Code First 1

These codes say to code first a condition named in the note, and B27.01 is one of the conditions named.

  • K77 Liver disorders in diseases classified elsewhere
    infectious mononucleosis with liver disease (B27.0-B27.9 with fifth character 9) names B27.0-B27.9, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS020
Other nervous system disorders (neither hereditary nor degenerative)
Default principal diagnosis: inpatient No · outpatient No
CCSR NVS015
Polyneuropathies
Default principal diagnosis: inpatient No · outpatient No
CCSR INF008
Viral infection
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Infectious Mononucleosis

    a common, acute infection usually caused by the epstein-barr virus (herpesvirus 4, human). there is an increase in mononuclear white blood cells and other atypical lymphocytes, generalized lymphadenopathy, splenomegaly, and occasionally hepatomegaly with hepatitis.

Patient EducationClinical

Infectious Mononucleosis

Infectious mononucleosis (mono) is a disease caused by viruses.The most common cause is the Epstein-Barr virus (EBV). Mono is contagious, which means it can spread from person to person. It is common among teenagers and young adults, especially college students.

The full article covers:

  • What is infectious mononucleosis (mono)?
  • What causes infectious mononucleosis (mono)?
  • What are the symptoms of infectious mononucleosis (mono)?
  • How is infectious mononucleosis (mono) diagnosed?
  • What are the treatments for infectious mononucleosis (mono)?
  • Can infectious mononucleosis (mono) be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert B27.01 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
075 Infectious mononucleosis
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About B27.01Overview

What is the ICD-10 code for gammaherpesviral mononucleosis with polyneuropathy?

The ICD-10-CM code for gammaherpesviral mononucleosis with polyneuropathy is B27.01 (sometimes written as B2701). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is B27.01 (Gammaherpesviral mononucleosis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report gammaherpesviral mononucleosis with polyneuropathy on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does B27.01 group to?

When gammaherpesviral mononucleosis with polyneuropathy is the principal diagnosis on an inpatient stay, it groups to MS-DRG 866, 865, with relative weights from 0.8691 to 1.3153 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of B27.01?

Under the General Equivalence Mappings, gammaherpesviral mononucleosis with polyneuropathy converts to ICD-9-CM 075 (infectious mononucleosis). The mapping is approximate, so confirm the match fits the documentation.