What is ICD-10 code B38.1?

B38.1 is the ICD-10-CM diagnosis code for Chronic pulmonary coccidioidomycosis. A long-lasting fungal lung infection caused by Coccidioides that persists over time. It belongs to the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99). B38.1 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. B38.1 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. B38.1 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. B38.1 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for B38.1?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. B38.1 was a payment HCC under V24 (Pneumococcal Pneumonia, Empyema, Lung Abscess) but the V28 recalibration removed it from the risk adjustment model. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting B38.1?

Verify the duration and chronicity of symptoms in the medical record before assigning this code Note any complications such as cavitation or fibrosis that may affect treatment decisions Because B38.1 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

B38.1: Chronic pulmonary coccidioidomycosis — ICD-10 | Pneumococcal Pneumonia, Empyema, Lung

ICD-10-CM Code View

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Code lookupB38.1Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

B38.1

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

Chronic pulmonary coccidioidomycosis

A long-lasting fungal lung infection caused by Coccidioides that persists over time.

Buddy Insight

Chronic pulmonary coccidioidomycosis represents a persistent fungal lung infection lasting months to years, often mimicking tuberculosis or lung malignancy on imaging.

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Mapped

HCC 115

Pneumococcal Pneumonia, Empye...

RAF 0.339

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 115

Pneumococcal Pneumonia, Empye...

RAF 0.0

RXHCC

Not risk-adjusted for this model/period.

RAF 0

Code Trumping

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Code Book Path

Official

B38Coccidioidomycosis

B38.1Chronic pulmonary coccidioidomycosis

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for B38.1 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for B38.1 in this effective period.

Related Child Codes

Official

B38.0Acute pulmonary coccidioidomycosis

B38.2Pulmonary coccidioidomycosis, unspecified

B38.3Cutaneous coccidioidomycosis

B38.4Coccidioidomycosis meningitis

B38.7Disseminated coccidioidomycosis

Includes

Official

ICD-10-CM does not list Includes notes for B38.1 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for B38.1 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for B38.1 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for B38.1 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for B38.1 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Duration of illness documented as chronic (persisting beyond 6 weeks)

Serial imaging showing progressive or stable cavitary disease, fibrosis, or nodules

Positive coccidioidomycosis serology with complement fixation titers

Documentation of ongoing antifungal treatment or monitoring plan

MEAT Support

HCC Buddy guidance

Duration of illness documented as chronic (persisting beyond 6 weeks)

Serial imaging showing progressive or stable cavitary disease, fibrosis, or nodules

Positive coccidioidomycosis serology with complement fixation titers

Documentation of ongoing antifungal treatment or monitoring plan

Audit Caution

HCC Buddy guidance

Defaulting to the unspecified B38.2 when the provider clearly documents chronic course, cavitary disease, or fibrosis

Confusing chronic coccidioidomycosis with residual scarring — active chronic infection requires ongoing treatment, while scarring is a sequela

Not querying the provider when radiology reads suggest chronic fungal infection without specifying the organism

Common Mistakes

HCC Buddy guidance

B38.0 (Acute pulmonary coccidioidomycosis) - acute form is for initial presentation with rapid symptom onset; chronic implies prolonged course

B38.2 (Pulmonary coccidioidomycosis, unspecified) - should not be used when chronicity is documented

A15.0 (Tuberculosis of lung) - can mimic chronic cocci on imaging; microbiologic confirmation differentiates them

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is B38.1 an HCC code?

Yes. B38.1 maps to Pneumococcal Pneumonia, Empyema, Lung Abscess under the V24 model but is not retained in V28.

HCC Category Mapping

V24HCC 115, Pneumococcal Pneumonia, Empyema, Lung Abscess

0.339

ESRDHCC 115, Pneumococcal Pneumonia, Empyema, Lung Abscess

0.000

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.

Work B38.1 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for B38.1

For B38.1to 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 B38.1 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

B38.1 is the ICD-10-CM diagnosis code for chronic pulmonary coccidioidomycosis. A long-lasting fungal lung infection caused by Coccidioides that persists over time. B38.1 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering mycoses (b35-b49).

Under the older CMS-HCC V24 model, B38.1 maps to Pneumococcal Pneumonia, Empyema, Lung Abscess (HCC 115) with a community, non-dual, aged base RAF weight of 0.339. 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.

Verify the duration and chronicity of symptoms in the medical record before assigning this code. Because B38.1 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 B38.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Verify the duration and chronicity of symptoms in the medical record before assigning this code
•Note any complications such as cavitation or fibrosis that may affect treatment decisions

Clinical Significance

Chronic pulmonary coccidioidomycosis represents a persistent fungal lung infection lasting months to years, often mimicking tuberculosis or lung malignancy on imaging. This code captures the ongoing resource utilization and monitoring needs of these patients, including long-term antifungal therapy and serial imaging surveillance.

Documentation Requirements

✓Duration of illness documented as chronic (persisting beyond 6 weeks)
✓Serial imaging showing progressive or stable cavitary disease, fibrosis, or nodules
✓Positive coccidioidomycosis serology with complement fixation titers
✓Documentation of ongoing antifungal treatment or monitoring plan
✓Clinical differentiation from tuberculosis or malignancy (biopsy or culture results)

Commonly Confused Codes

•B38.0 (Acute pulmonary coccidioidomycosis) - acute form is for initial presentation with rapid symptom onset; chronic implies prolonged course
•B38.2 (Pulmonary coccidioidomycosis, unspecified) - should not be used when chronicity is documented
•A15.0 (Tuberculosis of lung) - can mimic chronic cocci on imaging; microbiologic confirmation differentiates them