2026 ICD-10-CM Diagnosis Code B39.1Chronic pulmonary histoplasmosis capsulati
ICD-10-CM Codes›A00–B99›B35-B49›B39
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Chronic Condition
B39.1 is a billable ICD-10-CM diagnosis code for chronic pulmonary histoplasmosis capsulati. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 177 through 179, 791, 793, 974 through 976. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 112 closely related codes. Coders also document this condition as chronic pulmonary histoplasmosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fungal infections and Pneumonia (except that caused by tuberculosis).
B39.1 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 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
B39.1 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 2026 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 histoplasmosis
- Pulmonary histoplasmosis
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
Histoplasmosis
infection resulting from exposure to the fungus histoplasma.Histoplasma
a mitosporic onygenales fungal genus causing histoplasmosis in humans and animals. its single species is histoplasma capsulatum which has two varieties: h. capsulatum var. capsulatum and h. capsulatum var. duboisii. its teleomorph is ajellomyces capsulatus.Histoplasmosis
a disease caused by the fungus histoplasma capsulatum. it primarily affects the lungs but can also occur as a disseminated disease that affects additional organs. the acute respiratory disease has symptoms similar to those of a cold or flu and it usually resolves without treatment in healthy individuals. the disseminated form is generally fatal if untreated.
Patient EducationClinical
Histoplasmosis
Histoplasmosis is an infection caused by a fungus called Histoplasma. This fungus is common in the central and eastern United States, especially around the Ohio and Mississippi River valleys. It can also be found in parts of Central and South America, Africa, Asia, and Australia.
The full article covers:
- What is histoplasmosis?
- How do you get histoplasmosis?
- What are the symptoms of histoplasmosis?
- How is histoplasmosis diagnosed?
- What are the treatments for histoplasmosis?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert B39.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B39.1Overview
What is the ICD-10 code for chronic pulmonary histoplasmosis capsulati?
The ICD-10-CM code for chronic pulmonary histoplasmosis capsulati is B39.1 (sometimes written as B391). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is B39.1 (Histoplasmosis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report chronic pulmonary histoplasmosis capsulati on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does B39.1 group to?
When chronic pulmonary histoplasmosis capsulati is the principal diagnosis on an inpatient stay, it groups to MS-DRG 177, 178, 179, 791, 793, 974, 975, 976, with relative weights from 0.7550 to 4.1696 depending on complications. Higher weights mean higher Medicare reimbursement.
Is B39.1 a CC or MCC?
CMS lists B39.1 as an MCC (major complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 112 closely related codes in its exclusion list.
What is the ICD-9 equivalent of B39.1?
Under the General Equivalence Mappings, chronic pulmonary histoplasmosis capsulati converts to ICD-9-CM 115.05 (histoplasm caps pneumon). The mapping is approximate, so confirm the match fits the documentation.
Does B39.1 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. B39.1 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).
