2026 ICD-10-CM Diagnosis Code B40.81Blastomycotic meningoencephalitis

ICD-10-CM Codes›A00–B99›B35-B49›B40

ICD-10-CM B40.81
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

B40.81 is a billable ICD-10-CM diagnosis code for blastomycotic meningoencephalitis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 867 through 869. Coders also document this condition as meningoencephalitis due to Blastomyces dermatitidis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Encephalitis and Fungal infections.

Code Identity

ICD-10-CM Code
B40.81
Billable Status
Yes — Valid for Submission
Code Describes
Blastomycotic meningoencephalitis
Short Description
Blastomycotic meningoencephalitis
Same as the full description in the CMS dataset.
Parent Code
B40.8
Other forms of blastomycosis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB35-B49Mycoses
CategoryB40Blastomycosis
This CodeB40.81Blastomycotic meningoencephalitis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Meningoencephalitis due to Blastomyces dermatitidis

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Meningomyelitis due to blastomycosis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Meningoencephalitis
      • in (due to)
        • blastomycosis NEC
    • Meningomyelitis
      • blastomycotic NEC

Clinical ClassificationClinical

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

CCSR NVS002
Encephalitis
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR INF004
Fungal infections
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Fungal Infections

If you have ever had athlete's foot or a yeast infection, you can blame a fungus. A fungus is a primitive organism. Mushrooms, mold and mildew are examples. Fungi live in air, in soil, on plants and in water. Some live in the human body. Only about half of all types of fungi are harmful.

Read the full article at MedlinePlus

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

Convert B40.81 to ICD-9-CMHistory

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

ICD-9-CM
116.0 Blastomycosis
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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About B40.81Overview

Is B40.81 (Other forms of blastomycosis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report blastomycotic meningoencephalitis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does B40.81 group to?

When blastomycotic meningoencephalitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 867, 868, 869, with relative weights from 0.7297 to 2.0932 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of B40.81?

Under the General Equivalence Mappings, blastomycotic meningoencephalitis converts to ICD-9-CM 116.0 (blastomycosis). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.