2026 ICD-10-CM Diagnosis Code B40.3Cutaneous blastomycosis

ICD-10-CM Codes›A00–B99›B35-B49›B40

ICD-10-CM B40.3
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

B40.3 is a billable ICD-10-CM diagnosis code for cutaneous blastomycosis. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fungal infections and Other specified and unspecified skin disorders.

Code Identity

ICD-10-CM Code
B40.3
Billable Status
Yes — Valid for Submission
Code Describes
Cutaneous blastomycosis
Short Description
Cutaneous blastomycosis
Same as the full description in the CMS dataset.
Parent Code
B40
Blastomycosis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB35-B49Mycoses
CategoryB40Blastomycosis
This CodeB40.3Cutaneous blastomycosis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Cutaneous blastomycosis
  • Disseminated cutaneous blastomycosis
  • Disseminated cutaneous mycosis
  • Infection by Blastomyces dermatitidis
  • Primary cutaneous 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.

    • Blastomycosis, blastomycotic
      • cutaneous
    • Blastomycosis, blastomycotic
      • skin
    • Dermatitis(eczematous)
      • blastomycotic

Clinical ClassificationClinical

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

CCSR INF004
Fungal infections
Default principal diagnosis: inpatient No · outpatient No
CCSR SKN007
Other specified and unspecified skin disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Blastomycosis

    a fungal infection by blastomyces that may appear in two forms: 1, a primary lesion characterized by the formation of a small cutaneous nodule and small nodules along the lymphatics that may heal within several months; and 2, chronic granulomatous lesions characterized by thick crusts, warty growths, and unusual vascularity and infection in the middle or upper lobes of the lung.

  • Lobomycosis

    a chronic, fungal, subcutaneous infection endemic in rural regions in south america and central america. the causal organism is lacazia labol.

  • Paracoccidioidomycosis

    a mycosis affecting the skin, mucous membranes, lymph nodes, and internal organs. it is caused most often by paracoccidioides brasiliensis. it is also called paracoccidioidal granuloma.

  • Blastomyces

    a genus of onygenacetous mitosporic fungi whose perfect state is ajellomyces (see onygenales). the species blastomyces dermatitidis (perfect state is ajellomyces dermatitidis) causes blastomycosis.

  • Blastomycosis

    a fungal infection caused by inhalation of spores of blastomyces dermatitidis. it presents with flu-like symptoms including fever, chills, cough, pleuritic chest pain and myalgias. it may lead to a chronic granulomatous pulmonary infection and disseminate to other anatomic sites including skin, nervous system and bones.

  • North American Blastomycosis|Blastomyces Dermatitidis Infection

    a pulmonary disease resulting from infection with blastomyces dermatitidis, which is prevalent in north america.

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 B40.3 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 B40.3Overview

Is B40.3 (Blastomycosis) a billable code?

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

What MS-DRG does B40.3 group to?

When cutaneous blastomycosis 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 B40.3?

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

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.