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

A81.2 is the billable ICD-10-CM code for progressive multifocal leukoencephalopathy, in category A81 (Atypical virus infections of central nervous system) of the Viral and prion infections of the central nervous system section. As a principal diagnosis it groups to MS-DRG 056 Degenerative Nervous System Disorders with MCC, MS-DRG 057 Degenerative Nervous System Disorders without MCC (MDC 01 MDC 01: Diseases and Disorders of the Nervous System); or MS-DRG 974 HIV with Major Related Condition with MCC, MS-DRG 975 HIV with Major Related Condition with CC, MS-DRG 976 HIV with Major Related Condition without CC/MCC (MDC 25 MDC 25: Human Immunodeficiency Virus Infections). It maps to HCC 127 (Dementia, Mild or Unspecified) in CMS-HCC V28. As a secondary diagnosis it is a CC, excluded with 175 principal diagnoses. 3 LCD billing and coding articles list it as covered.

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: ICD-10-CM code descriptions: FY2027 (effective October 1, 2026); IPPS Table 5 (MS-DRG weights): v44 FY2027 (final rule + CN3) (effective October 1, 2026); ICD-10-CM to HCC mapping: PY2027 initial ICD-10-CM mappings (dates of service 2026) (payment year 2027); Medicare Coverage Database billing and coding articles: MCD release October 8, 2026 (effective October 4, 2026). Next CMS release: FY2028 code files, effective October 1, 2027 for the ICD-10-CM code descriptions; FY2028 final rule (August 2027), effective October 1, 2027; an April 1 interim grouper update when CMS issues one for the IPPS Table 5 (MS-DRG weights); PY2028 advance notice (February 2027) and the PY2027 midyear final mapping (spring 2027) for the ICD-10-CM to HCC mapping; weekly, every Thursday for the Medicare Coverage Database billing and coding articles.

Code
A81.2
billable FY2027 ICD-10-CM code
Category
A81 Atypical virus infections of central nervous system
Chapter
1: Certain infectious and parasitic diseases (A00-B99)
CC/MCC (MS-DRG v44)
CC
CMS-HCC V28
HCC 127
POA reporting
Required

Tabular list notes for A81.2

The tabular list has no notes on A81.2 itself; the notes below apply from its parent headings.

Inherited from A81 (Atypical virus infections of central nervous system)

Includes
  • diseases of the central nervous system caused by prions
Use additional code
  • code, if applicable, to identify:
  • dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4)
  • dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)
  • dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3)
  • dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2)
  • dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0)
  • mild neurocognitive disorder due to known physiological condition (F06.7-)

MS-DRG grouping when A81.2 is the principal diagnosis

MS-DRG v44 groups for A81.2 as principal diagnosis
MDCMS-DRGs
01 MDC 01: Diseases and Disorders of the Nervous System056057
25 MDC 25: Human Immunodeficiency Virus Infections974975976

The final group also depends on procedures, secondary diagnoses and discharge status; the MS-DRG lookup for A81.2 shows the full grouping logic.

CC/MCC status and inpatient edits

As a secondary diagnosis, A81.2 is a CC under MS-DRG v44, unless the principal diagnosis is one of the 175 codes in its exclusion list. Check A81.2 against a principal diagnosis.

  • Present on admission: a POA indicator is required on inpatient claims.

CMS-HCC V28 risk adjustment

In the PY2027 mapping, A81.2 maps to HCC 127 (Dementia, Mild or Unspecified). The HCC lookup shows the RAF weight and the hierarchy.

LCD billing and coding articles that list A81.2

3 current Medicare billing and coding articles list A81.2 among the diagnoses that support medical necessity for the services they cover.

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Frequently asked questions

What does ICD-10-CM A81.2 mean?

A81.2 means progressive multifocal leukoencephalopathy. It is one of 10 billable codes under A81, atypical virus infections of central nervous system.

Which MS-DRG does A81.2 group to?

As the principal diagnosis, A81.2 groups to MS-DRG 056 Degenerative Nervous System Disorders with MCC, MS-DRG 057 Degenerative Nervous System Disorders without MCC (MDC 01 MDC 01: Diseases and Disorders of the Nervous System); or MS-DRG 974 HIV with Major Related Condition with MCC, MS-DRG 975 HIV with Major Related Condition with CC, MS-DRG 976 HIV with Major Related Condition without CC/MCC (MDC 25 MDC 25: Human Immunodeficiency Virus Infections) under MS-DRG v44, before procedures and secondary diagnoses are applied.

Does A81.2 map to an HCC?

Yes: HCC 127, Dementia, Mild or Unspecified, in the PY2027 CMS-HCC V28 mapping.

Is A81.2 a CC or MCC?

A81.2 is a CC under MS-DRG v44; 175 principal diagnoses exclude it.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

The descriptor and notes are reproduced from the FY2027 ICD-10-CM files; MS-DRG, CC/MCC and HCC facts come from the CMS FY2027 and PY2027 tables. Code from the medical record and the ICD-10-CM Official Guidelines. Not legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.