DxCodebookFY2027 · Oct 1, 2026 – Sep 30, 2027

A86 diagnosis code · Billable category · FY2027

A86 Unspecified viral encephalitis

  • Billable
  • CC
  • POA reported

A86 ICD-10 code: a billable diagnosis code in FY2027; the category has no subdivisions.

Where it sits

  1. Chapter 1 Certain infectious and parasitic diseases (A00-B99)
  2. A80-A89 Viral and prion infections of the central nervous system (A80-A89)
  3. A86 Unspecified viral encephalitis
CC / MCC
CC
MS-DRG
097-099, 974-976
HCC V28
–
POA
Reported
Code Editor
–
Index entries
10

Instructions

At A86

Inclusion terms

  • Viral encephalomyelitis NOS
  • Viral meningoencephalitis NOS

Notes that also apply

Block A80-A89 instructions (Excludes1 3): printed on the block page.

Chapter 1 instructions (Includes 1, Excludes2 5, Use additional code 1): printed on the chapter 1 page.

Index entries

  • Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)acute → A86
  • Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)endemic (viral) → A86
  • Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)epidemic NEC (viral) → A86
  • Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)infectious (acute) (virus) NEC → A86
  • Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)postviral NEC → A86
  • Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)viral, virus → A86
  • Meningoencephalitisacute NEC → A86
  • Meningoencephalitisinfectious (acute) (viral) → A86
  • Meningoencephalitisvirus NEC → A86
  • Meningoencephalomyelitisacute NEC (viral) → A86

NCHS Alphabetic Index. Index first, then the Tabular List.

Medicare grouping and edits

CMS files for A86
CC / MCCCC
PDX exclusion list0148 (186 codes)
Appendix BMDC 01 Diseases and Disorders of the Nervous System, MS-DRG 097-099 (Non-Bacterial Infection of Nervous System Except Viral Meningitis with MCC…); MDC 25 Human Immunodeficiency Virus Infections, MS-DRG 974-976 (HIV with Major Related Condition with MCC…)
Code Editor–
POAReported
HCC V28–

CC as a secondary diagnosis, not when the principal diagnosis is on its PDX exclusion list.

CMS: MS-DRG v44 (Appendix B, C), MCE v44, POA list FY2027, 2027 Initial ICD-10-CM Mappings. What the rows mean.

Hierarchy