A81.2 ICD-10-CM Code: Progressive multifocal leukoencephalopathy

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for A81.2 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on A81.2 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for A81.2

MedCoder structured workflow — derived from this code’s own official record

Before you code A81.2

1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with A81.2. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the documentation support a condition named in A81.2’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewG14, B91, B94.1

Consider A81.2. Then work the Use Additional Code note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

The conditions the Use Additional Code note names

Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

• Excludes1 — check before selecting A81.2(3 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with A81.2: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareG14, B91, B94.1

  See the official tabular notes · Guidelines I.A.12.a

• Use Additional Code — after identifying A81.2(7 notes)

  Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with A81.2 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

  ReviewF02.84, F02.A4, F02.B4, F02.C4, F02.81, F02.A1

  See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (2)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Leukoencephalopathy, multifocal (progressive)
• Leukoencephalopathy, progressive multifocal

Don’t confuse A81.2 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of A81.2 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• G14— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of postpolio syndrome moves the case to G14; the two are not reported together unless documented as unrelated.

  Full comparison: A81.2 vs G14 →

• B91— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of sequelae of poliomyelitis moves the case to B91; the two are not reported together unless documented as unrelated.

  Full comparison: A81.2 vs B91 →

• B94.1— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of sequelae of viral encephalitis moves the case to B94.1; the two are not reported together unless documented as unrelated.

  Full comparison: A81.2 vs B94.1 →

• A81.9— Specificity relationship (Review)

  Overlapping diagnoses in the same category.

  Overlapping codes in the same category — the documentation decides which is the more specific fit.

  What moves you there: A record that documents no more than “Atypical virus infection of central nervous system, unspecified” takes A81.9; specificity in the record moves it back here.

  Full comparison: A81.2 vs A81.9 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 175 clinically related codes on its CMS exclusion list. Does not count toward severity when the stay groups to DRGs 974-976 (HIV with Major Related Condition).

Named in the grouper logic of 5 MS-DRGs: DRG 056 (MDC 01), DRG 057 (MDC 01), DRG 974 (MDC 25), DRG 975 (MDC 25), DRG 976 (MDC 25).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):NVS003 — Other specified CNS infection and poliomyelitis (default); INF008 — Viral infection.

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

A17.82 — Tuberculous meningoencephalitis, A50.42 — Late congenital syphilitic encephalitis, A52.14 — Late syphilitic encephalitis, A75.9 — Typhus fever, unspecified, A79.9 — Rickettsiosis, unspecified, A81.00 — Creutzfeldt-Jakob disease, unspecified, A81.01 — Variant Creutzfeldt-Jakob disease, A81.09 — Other Creutzfeldt-Jakob disease, A81.1 — Subacute sclerosing panencephalitis, A81.81 — Kuru, A81.82 — Gerstmann-Sträussler-Scheinker syndrome, A81.83 — Fatal familial insomnia, A81.89 — Other atypical virus infections of central nervous system, A81.9 — Atypical virus infection of central nervous system, unspecified, A83.0 — Japanese encephalitis, A83.1 — Western equine encephalitis, A83.2 — Eastern equine encephalitis, A83.3 — St Louis encephalitis, A83.4 — Australian encephalitis, A83.5 — California encephalitis, +154 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Dementia, Mild or Unspecified) for risk-adjusted payment.

A81.00 — Creutzfeldt-Jakob disease, unspecified, A81.01 — Variant Creutzfeldt-Jakob disease, A81.09 — Other Creutzfeldt-Jakob disease, A81.1 — Subacute sclerosing panencephalitis, A81.81 — Kuru, A81.82 — Gerstmann-Sträussler-Scheinker syndrome, A81.83 — Fatal familial insomnia, A81.89 — Other atypical virus infections of central nervous system, A81.9 — Atypical virus infection of central nervous system, unspecified, F01.50 — Vascular dementia, unspecified severity, without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety, F01.511 — Vascular dementia, unspecified severity, with agitation, F01.518 — Vascular dementia, unspecified severity, with other behavioral disturbance, F01.52 — Vascular dementia, unspecified severity, with psychotic disturbance, F01.53 — Vascular dementia, unspecified severity, with mood disturbance, F01.54 — Vascular dementia, unspecified severity, with anxiety, F01.A0 — Vascular dementia, mild, without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety, F01.A11 — Vascular dementia, mild, with agitation, F01.A18 — Vascular dementia, mild, with other behavioral disturbance, F01.A2 — Vascular dementia, mild, with psychotic disturbance, F01.A3 — Vascular dementia, mild, with mood disturbance, +44 more

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Dementia, Severe, Dementia, Moderate

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Other specified CNS infection and poliomyelitis, Viral infection).

A80.0 — Acute paralytic poliomyelitis, vaccine-associated, A80.1 — Acute paralytic poliomyelitis, wild virus, imported, A80.2 — Acute paralytic poliomyelitis, wild virus, indigenous, A80.30 — Acute paralytic poliomyelitis, unspecified, A80.39 — Other acute paralytic poliomyelitis, A80.4 — Acute nonparalytic poliomyelitis, A80.9 — Acute poliomyelitis, unspecified, A81.00 — Creutzfeldt-Jakob disease, unspecified, A81.01 — Variant Creutzfeldt-Jakob disease, A81.09 — Other Creutzfeldt-Jakob disease, A81.81 — Kuru, A81.82 — Gerstmann-Sträussler-Scheinker syndrome, A81.83 — Fatal familial insomnia, A81.89 — Other atypical virus infections of central nervous system, A81.9 — Atypical virus infection of central nervous system, unspecified, A82.0 — Sylvatic rabies, A82.1 — Urban rabies, A82.9 — Rabies, unspecified, A88.0 — Enteroviral exanthematous fever [Boston exanthem], A88.1 — Epidemic vertigo, +297 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Leukoencephalopathy”; these codes share that main term but sit in a different category of the Tabular List.

E75.25 — Metachromatic leukodystrophy (metachromatic), E88.43 — Disorders of mitochondrial tRNA synthetases (with, thalamus - brainstem involvement - high lactate), G04.02 — Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis (postimmunization and postvaccinal), G92.8 — Other toxic encephalopathy (heroin vapor), G93.42 — Megalencephalic leukoencephalopathy with subcortical cysts (megalencephalic, with subcortical cysts), G93.43 — Leukoencephalopathy with calcifications and cysts (with, calcifications and cysts), G93.44 — Adult-onset leukodystrophy with axonal spheroids (adult-onset, with axonal spheroids), G93.49 — Other encephalopathy, G93.6 — Cerebral edema (reversible, posterior), I67.3 — Progressive vascular leukoencephalopathy (Binswanger's)

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

HIV Screening Test

Contextual Map

Every relationship of A81.2 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Hierarchy

• A00-B99 — Chapter 1: Certain Infectious and Parasitic Diseases (A00-B99) (A00-B99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A80-A89 — Viral and prion infections of the central nervous system[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Clinical classification (CCSR)

• NVS003 — Other specified CNS infection and poliomyelitis[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)
• INF008 — Viral infection[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

Risk adjustment (CMS-HCC)

• HCC 127 — Dementia, Mild or Unspecified [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC). Not counted when the stay groups to DRGs 974-976 (HIV with Major Related Condition).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 056 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITH MCC[MS-DRG]: “DEGENERATIVE NERVOUS SYSTEM DISORDERS WITH MCC (MDC 01)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 057 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITHOUT MCC[MS-DRG]: “DEGENERATIVE NERVOUS SYSTEM DISORDERS WITHOUT MCC (MDC 01)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 974 — HIV WITH MAJOR RELATED CONDITION WITH MCC[MS-DRG]: “HIV WITH MAJOR RELATED CONDITION WITH MCC (MDC 25)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 975 — HIV WITH MAJOR RELATED CONDITION WITH CC[MS-DRG]: “HIV WITH MAJOR RELATED CONDITION WITH CC (MDC 25)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 976 — HIV WITH MAJOR RELATED CONDITION WITHOUT CC/MCC[MS-DRG]: “HIV WITH MAJOR RELATED CONDITION WITHOUT CC/MCC (MDC 25)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 01 — Diseases and Disorders of the Nervous System[MDC crossing]: “Diseases and Disorders of the Nervous System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 8,892 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
• MDC 25 — Human Immunodeficiency Virus Infections[MDC crossing]: “Human Immunodeficiency Virus Infections — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Leukoencephalopathy, multifocal (progressive)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Leukoencephalopathy, progressive multifocal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (12)

• A81 — Atypical virus infections of central nervous system[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A81.0 — Creutzfeldt-Jakob disease[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A81.00 — Creutzfeldt-Jakob disease, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A81.01 — Variant Creutzfeldt-Jakob disease[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A81.09 — Other Creutzfeldt-Jakob disease[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A81.1 — Subacute sclerosing panencephalitis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A81.8 — Other atypical virus infections of central nervous system[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A81.81 — Kuru[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 4 more

Change history

• FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Risk adjustment Official source data

2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to A81.2 in its code family, with their registry titles.

• A81.0 — Creutzfeldt-Jakob disease
• A81.00 — Creutzfeldt-Jakob disease, unspecified
• A81.01 — Variant Creutzfeldt-Jakob disease
• A81.09 — Other Creutzfeldt-Jakob disease
• A81.1 — Subacute sclerosing panencephalitis
• A81.8 — Other atypical virus infections of central nervous system
• A81.81 — Kuru
• A81.82 — Gerstmann-Sträussler-Scheinker syndrome
• A81.83 — Fatal familial insomnia
• A81.89 — Other atypical virus infections of central nervous system

View all codes in the A81 family