2027 ICD-10-CM Diagnosis Code B40.1Chronic pulmonary blastomycosis
ICD-10-CM Codes›A00–B99›B35-B49›B40
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Chronic Condition
B40.1 is a billable ICD-10-CM diagnosis code for chronic pulmonary blastomycosis. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fungal infections and Other specified and unspecified lower respiratory disease.
B40.1 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 115 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 115, ESRD (V21) category 115, and ESRD (V24) category 115 for payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
B40.1 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Chronic pulmonary blastomycosis
- Infection by Blastomyces dermatitidis
- Pulmonary blastomycosis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to B40.1: 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.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name B40.1, its category, or a range that includes it.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
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 B40.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B40.1Overview
What is the ICD-10 code for chronic pulmonary blastomycosis?
The ICD-10-CM code for chronic pulmonary blastomycosis is B40.1 (sometimes written as B401). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is B40.1 (Blastomycosis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report chronic pulmonary blastomycosis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does B40.1 group to?
When chronic pulmonary blastomycosis 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 B40.1 a CC or MCC?
CMS lists B40.1 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 B40.1 be reported with a code from B41?
Not as a rule. The Excludes1 note at B40, which applies to B40.1, 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).
Does B40.1 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. B40.1 mapped to HCC 115 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 115 (Pneumococcal Pneumonia/Empyema/Lung Abscess), ESRD (V21) category 115 (Pneumococcal Pneumonia/Empyema/Lung Abscess), and ESRD (V24) category 115 (Pneumococcal Pneumonia/Empyema/Lung Abscess).
