2027 ICD-10-CM Diagnosis Code B40.9Blastomycosis, unspecified
ICD-10-CM Codes›A00–B99›B35-B49›B40
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
B40.9 is a billable ICD-10-CM diagnosis code for blastomycosis, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 791, 793, 867 through 869. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 14 closely related codes. Coders also document this condition as blastomycosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fungal infections.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Blastomycosis
- Blastomycotic prostatitis
- Infection by Blastomyces dermatitidis
- Non-bacterial prostatitis
- Urogenital blastomycosis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to B40.9: its own notes plus those printed at B40, block B35-B49, and Chapter 1. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- diseases generally recognized as communicable or transmissible
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify resistance to antimicrobial drugs (Z16.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Blastomycosis, blastomycotic B40.9
North American B40.9
Chicago disease B40.9
Disease, diseased See Also: Syndrome;
Chicago B40.9
Gilchrist's disease B40.9
Infection, infected, infective (opportunistic) B99.9
Blastomyces, blastomycotic See Also: Blastomycosis;
North American B40.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
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 B40.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B40.9Overview
What is the ICD-10 code for blastomycosis, unspecified?
The ICD-10-CM code for blastomycosis, unspecified is B40.9 (sometimes written as B409). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is B40.9 (Blastomycosis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report blastomycosis, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does B40.9 group to?
When blastomycosis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 867, 869, 868, with relative weights from 0.6784 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is B40.9 a CC or MCC?
CMS lists B40.9 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 14 closely related codes in its exclusion list.
Can B40.9 be reported with a code from B41?
Not as a rule. The Excludes1 note at B40, which applies to B40.9, lists "Brazilian blastomycosis (B41.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
