B37.1 maps to CMS-HCC V28 6. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools

ICD-10-CM Code View

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Code lookupB37.1

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Mycoses (B35-B49)

B37.1

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Pulmonary candidiasis

A yeast infection of the lungs caused by Candida fungus, typically occurring in people with severely weakened immune systems. It can cause cough, fever, and difficulty breathing.

Buddy Insight

Pulmonary candidiasis is a serious deep fungal infection of the lungs caused by Candida species, occurring almost exclusively in severely immunocompromised patients.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 6

Opportunistic Infections

Coefficient HCC 6: 0.381 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 006

HHS-HCC 006 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 6

Opportunistic Infections

Code-level coefficient reference

RXHCC

Mapped

HCC 5

Opportunistic Infections

Code-level coefficient reference

Code Book Path

Official

B37Candidiasis B37.1Pulmonary candidiasis

Inclusion Terms

Official

Candidal bronchitis
Candidal pneumonia

Excludes 2

Official

carrier or suspected carrier of infectious disease (Z22.-)Inherited from A00-B99, B35-B49
infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)Inherited from A00-B99, B35-B49
infectious and parasitic diseases specific to the perinatal period (P35-P39)Inherited from A00-B99, B35-B49
influenza and other acute respiratory infections (J00-J22)Inherited from A00-B99, B35-B49
hypersensitivity pneumonitis due to organic dust (J67.-)Inherited from A00-B99, B35-B49
mycosis fungoides (C84.0-)Inherited from A00-B99, B35-B49

Related Codes

Official

B37.0Candidal stomatitis B37.2Candidiasis of skin and nail B37.3Candidiasis of vulva and vagina B37.4Candidiasis of other urogenital sites B37.5Candidal meningitis

Includes

Official

diseases generally recognized as communicable or transmissibleInherited from A00-B99, B37
candidosisInherited from A00-B99, B37
moniliasisInherited from A00-B99, B37

Excludes 1

Official

certain localized infections - see body system-related chaptersInherited from A00-B99, B37
neonatal candidiasis (P37.5)Inherited from A00-B99, B37

Code First

Official

No Code First sequencing instructions are included in this display for B37.1. Check the code and parent instructions in the Code Book.

Use Additional

Official

code to identify resistance to antimicrobial drugs (Z16.-)Inherited from A00-B99

Code Also

Official

No Code Also instructions are included in this display for B37.1. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Candida species confirmed from respiratory specimen (bronchoalveolar lavage, protected brush, or lung biopsy — NOT sputum alone, as Candida in sputum is usually colonization)

Chest imaging showing pulmonary infiltrates consistent with fungal pneumonia

Underlying immunocompromised condition documented (neutropenia, HIV, transplant, prolonged ICU stay)

Species identification if available (C. albicans, C. glabrata, C. krusei, etc.) for antifungal susceptibility

MEAT Support

HCC Buddy guidance

Candida species confirmed from respiratory specimen (bronchoalveolar lavage, protected brush, or lung biopsy — NOT sputum alone, as Candida in sputum is usually colonization)

Chest imaging showing pulmonary infiltrates consistent with fungal pneumonia

Underlying immunocompromised condition documented (neutropenia, HIV, transplant, prolonged ICU stay)

Species identification if available (C. albicans, C. glabrata, C. krusei, etc.) for antifungal susceptibility

Audit Caution

HCC Buddy guidance

Coding pulmonary candidiasis based on sputum culture alone — Candida in sputum usually represents colonization, not true pneumonia; invasive sampling is needed

Not coding the underlying immunodeficiency that predisposed to this opportunistic infection

Confusing Candida colonization of the airway with invasive pulmonary candidiasis — clinical and histological correlation is required

Using generic pneumonia codes when Candida is the confirmed causative organism from appropriate specimens

Common Mistakes

HCC Buddy guidance

B37.0 (Candidal stomatitis) — Oral thrush is localized to the mouth; pulmonary candidiasis is a deep organ infection

B44.0 (Invasive pulmonary aspergillosis) — Another fungal lung infection but caused by Aspergillus, not Candida; different treatment

B59 (Pneumocystosis) — Pneumocystis jirovecii pneumonia is another opportunistic fungal lung infection but requires different treatment (TMP-SMX)

B25.0 (Cytomegaloviral pneumonitis) — Viral opportunistic lung infection, not fungal

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is B37.1 an HCC code?

Yes. B37.1 (Pulmonary candidiasis) maps to HCC 6, Opportunistic Infections under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.381. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: B37.1 is billable and maps to V28 HCC 6, Opportunistic Infections. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: B37.1
Description: Pulmonary candidiasis
HCC (V28): HCC 6 — Opportunistic Infections
RAF reference coefficient: 0.381
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 6, Opportunistic Infections

0.381

ESRDHCC 6, Opportunistic Infections

Not separately weighted

RxHCCHCC 5, Opportunistic Infections

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work B37.1 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for B37.1

For B37.1, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Coder workflow notes

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What This Code Means

B37.1 is the ICD-10-CM diagnosis code for pulmonary candidiasis. A yeast infection of the lungs caused by Candida fungus, typically occurring in people with severely weakened immune systems. It can cause cough, fever, and difficulty breathing. B37.1 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering mycoses (b35-b49).

Under the CMS-HCC V28 risk adjustment model, B37.1 maps to Opportunistic Infections (HCC 6) with a source-labeled community, non-dual, aged reference coefficient of 0.381. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

This is a serious infection usually associated with immunocompromised patients; code any underlying immunodeficiency conditions. For B37.1, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for B37.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is a serious infection usually associated with immunocompromised patients; code any underlying immunodeficiency conditions
•Document whether this is a primary infection or a recurrent/chronic infection, as this affects treatment approach

Clinical Significance

Pulmonary candidiasis is a serious deep fungal infection of the lungs caused by Candida species, occurring almost exclusively in severely immunocompromised patients. It carries high mortality and signals profound immune dysfunction, requiring aggressive systemic antifungal therapy and investigation of the underlying immunodeficiency.

Documentation Requirements

✓Candida species confirmed from respiratory specimen (bronchoalveolar lavage, protected brush, or lung biopsy — NOT sputum alone, as Candida in sputum is usually colonization)
✓Chest imaging showing pulmonary infiltrates consistent with fungal pneumonia
✓Underlying immunocompromised condition documented (neutropenia, HIV, transplant, prolonged ICU stay)
✓Species identification if available (C. albicans, C. glabrata, C. krusei, etc.) for antifungal susceptibility
✓Antifungal treatment regimen: echinocandin, amphotericin B, or azole therapy

Commonly Confused Codes

•B37.0 (Candidal stomatitis): Oral thrush is localized to the mouth; pulmonary candidiasis is a deep organ infection
•B44.0 (Invasive pulmonary aspergillosis): Another fungal lung infection but caused by Aspergillus, not Candida; different treatment
•B59 (Pneumocystosis): Pneumocystis jirovecii pneumonia is another opportunistic fungal lung infection but requires different treatment (TMP-SMX)
•B25.0 (Cytomegaloviral pneumonitis): Viral opportunistic lung infection, not fungal