2026 ICD-10-CM Diagnosis Code B37.1Pulmonary candidiasis
ICD-10-CM Codes›A00–B99›B35-B49›B37
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 6
- Not Chronic
B37.1 is a billable ICD-10-CM diagnosis code for pulmonary candidiasis. 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 23 closely related codes. Coders also document this condition as candidiasis of lung. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fungal infections and Pneumonia (except that caused by tuberculosis).
For Medicare Advantage risk adjustment, B37.1 maps to CMS-HCC Category 6 (Opportunistic Infections) under the V28 model, adding a risk factor of about 0.381 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
B37.1 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
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.
- Candidiasis of lung
- Candidiasis of lung with AIDS
- Candidiasis of trachea
- Disorder of respiratory system co-occurrent with human immunodeficiency virus infection
- Neonatal candidiasis
- Neonatal candidiasis of lung
- Pneumonia with AIDS
- Respiratory disorder with AIDS
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Candidal bronchitis
- Candidal pneumonia
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
candidal B37.1
bronchitis B37.1
lung B37.1
pneumonia B37.1
pulmonary B37.1
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Neonatal Candidiasis
a fungal infection by any of the candida species in a newborn infant up to 28 days old.
Patient EducationClinical
Lung Diseases
When you breathe, your lungs take in oxygen from the air and deliver it to the bloodstream. The cells in your body need oxygen to work and grow. During a normal day, you breathe nearly 25,000 times. People with lung disease have difficulty breathing. Millions of people in the U.S. have lung disease.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert B37.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B37.1Overview
What is the ICD-10 code for pulmonary candidiasis?
The ICD-10-CM code for pulmonary candidiasis is B37.1 (sometimes written as B371). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is B37.1 (Candidiasis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report pulmonary candidiasis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does B37.1 group to?
When pulmonary candidiasis 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 B37.1 a CC or MCC?
CMS lists B37.1 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 23 closely related codes in its exclusion list.
What is the ICD-9 equivalent of B37.1?
Under the General Equivalence Mappings, pulmonary candidiasis converts to ICD-9-CM 112.4 (candidiasis of lung). The mapping is approximate, so confirm the match fits the documentation.
What HCC is B37.1?
B37.1 (pulmonary candidiasis) maps to CMS-HCC Category 6 (Opportunistic Infections), commonly written as HCC 6, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 6 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 5.
Does B37.1 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, B37.1 adds a risk adjustment factor of about 0.381 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.381 to 0.833 depending on the payment segment). HCC 6 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 6 category page.
