B37.1
BillablePulmonary candidiasis
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is B37.1 an HCC code?
Yes. B37.1 maps to Opportunistic Infections under the CMS-HCC V28 risk adjustment model (and Opportunistic Infections under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for B37.1
For B37.1 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- 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
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed B37.1 during that encounter — not just copy-forwarded from a problem list.
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 community, non-dual, aged base RAF weight of 0.439. Under the older V24 model, B37.1 mapped to the same category but with a base RAF weight of 0.440 — V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
This is a serious infection usually associated with immunocompromised patients; code any underlying immunodeficiency conditions. Because B37.1 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. 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, RAF weights, 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