Skip to content
HCC Buddy home

B45.1 ICD-10-CM Code: Cerebral cryptococcosis

B45.1 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 · free HCC coding tools

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupB45.1

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

B45.1

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

Cerebral cryptococcosis

A serious fungal infection of the brain caused by Cryptococcus, a fungus found in soil and bird droppings. This condition can cause inflammation of the brain and its protective membranes, leading to symptoms like headache, fever, and confusion.

Buddy the Bee presenting code insight

Buddy Insight

Cerebral cryptococcosis (cryptococcal meningitis/meningoencephalitis) is one of the most common AIDS-defining infections worldwide and carries significant mortality even with treatment.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 6

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

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 006

Code-level coefficient reference

ESRD/PACE

HCC 6

Code-level coefficient reference

RXHCC

HCC 5

Code-level coefficient reference

Code Book Path

Official
B45CryptococcosisB45.1Cerebral cryptococcosis

Inclusion Terms

Official
  • Cryptococcal meningitis
  • Cryptococcosis meningocerebralis

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
B45.0Pulmonary cryptococcosisB45.2Cutaneous cryptococcosisB45.3Osseous cryptococcosisB45.7Disseminated cryptococcosisB45.8Other forms of cryptococcosis

Includes

Official
  • diseases generally recognized as communicable or transmissibleInherited from A00-B99

Excludes 1

Official
  • certain localized infections - see body system-related chaptersInherited from A00-B99

Code First

Official

No Code First sequencing instructions are included in this display for B45.1. 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 B45.1. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Positive cerebrospinal fluid cryptococcal antigen or India ink preparation
Cerebrospinal fluid findings: elevated opening pressure, low glucose, elevated protein, lymphocytic pleocytosis
Neurologic symptoms documented: headache, altered mental status, cranial nerve palsies, neck stiffness
HIV status and CD4 count documented (typically <100 cells/microL)

MEAT Support

HCC Buddy guidance
Positive cerebrospinal fluid cryptococcal antigen or India ink preparation
Cerebrospinal fluid findings: elevated opening pressure, low glucose, elevated protein, lymphocytic pleocytosis
Neurologic symptoms documented: headache, altered mental status, cranial nerve palsies, neck stiffness
HIV status and CD4 count documented (typically <100 cells/microL)

Audit Caution

HCC Buddy guidance
Using unspecified meningitis (G03.9) or unspecified cryptococcosis (B45.9) when cerebrospinal fluid confirms cryptococcal meningitis
Not coding HIV disease (B20) as the underlying condition when it is the predisposing immunodeficiency
Failing to capture cerebral involvement when the patient presents with both pulmonary and central nervous system disease — both B45.0 and B45.1 should be coded
Missing immune reconstitution inflammatory syndrome in HIV patients starting antiretroviral therapy

Common Mistakes

HCC Buddy guidance
B45.0 (Pulmonary cryptococcosis) - lung involvement only; if both CNS and lung are affected, code both
B45.7 (Disseminated cryptococcosis) - use when multiple organs beyond CNS are involved
G03.9 (Meningitis, unspecified) - never use when cryptococcal etiology is confirmed
B45.9 (Cryptococcosis, unspecified) - always use B45.1 when cerebral/meningeal involvement is documented

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 B45.1 an HCC code?

Yes. B45.1 (Cerebral cryptococcosis) 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: B45.1 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
B45.1
Description
Cerebral cryptococcosis
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 B45.1 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for B45.1

For B45.1, 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

Get the V28 mapping + MEAT cheat sheet

One printable reference: check representative V28 mappings and the documentation reminders your note needs. Free, no card.

Free PDF. No card. Unsubscribe anytime.

What This Code Means

B45.1 is the ICD-10-CM diagnosis code for cerebral cryptococcosis. A serious fungal infection of the brain caused by Cryptococcus, a fungus found in soil and bird droppings. This condition can cause inflammation of the brain and its protective membranes, leading to symptoms like headache, fever, and confusion. B45.1 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, B45.1 maps to Opportunistic Infections (HCC 6) with a source-labeled community, non-dual, aged reference coefficient of 0.381. No V24 mapping is shown for B45.1; use the applicable model and payment year when reviewing the V28 mapping. 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.

Cerebral cryptococcosis is typically associated with immunocompromised patients (HIV/AIDS, organ transplant recipients); verify if an underlying immunodeficiency condition is documented and coded separately. For B45.1, 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 B45.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Cerebral cryptococcosis is typically associated with immunocompromised patients (HIV/AIDS, organ transplant recipients); verify if an underlying immunodeficiency condition is documented and coded separately
  • •Ensure the documentation specifies 'cerebral' or 'CNS' involvement, as cryptococcosis can affect other sites (pulmonary, disseminated) and requires different codes

Clinical Significance

Cerebral cryptococcosis (cryptococcal meningitis/meningoencephalitis) is one of the most common AIDS-defining infections worldwide and carries significant mortality even with treatment. It is the leading cause of meningitis in sub-Saharan Africa and represents a critical diagnosis requiring emergent antifungal therapy and intracranial pressure management.

Documentation Requirements

  • ✓Positive cerebrospinal fluid cryptococcal antigen or India ink preparation
  • ✓Cerebrospinal fluid findings: elevated opening pressure, low glucose, elevated protein, lymphocytic pleocytosis
  • ✓Neurologic symptoms documented: headache, altered mental status, cranial nerve palsies, neck stiffness
  • ✓HIV status and CD4 count documented (typically <100 cells/microL)
  • ✓Treatment regimen: induction (amphotericin B + flucytosine), consolidation, maintenance phases

Commonly Confused Codes

  • •B45.0 (Pulmonary cryptococcosis) - lung involvement only; if both CNS and lung are affected, code both
  • •B45.7 (Disseminated cryptococcosis) - use when multiple organs beyond CNS are involved
  • •G03.9 (Meningitis, unspecified) - never use when cryptococcal etiology is confirmed
  • •B45.9 (Cryptococcosis, unspecified) - always use B45.1 when cerebral/meningeal involvement is documented

Child Codes

B45.0Pulmonary cryptococcosis
HCC 6
B45.1Cerebral cryptococcosis
HCC 6
B45.2Cutaneous cryptococcosis
HCC 6
B45.3Osseous cryptococcosis
HCC 6
B45.7Disseminated cryptococcosis
HCC 6
B45.8Other forms of cryptococcosis
HCC 6
B45.9Cryptococcosis, unspecified
HCC 6

Code Hierarchy

└B45Cryptococcosis└B45.1Cerebral cryptococcosis
└B45.1Cerebral cryptococcosis

Also searched as

  • B45 1
  • B451

For B45.1, 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.

B45.1 maps to CMS-HCC V28 category 6, Opportunistic Infections. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for B45.1. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

Work B45.1 in HCC Buddy

Open B45.1 in the Code Book for the full Index-to-Tabular path, MEAT checklist, and V28 HCC mapping, or in the Encoder to code from a keyword search. Pro includes 7 days to try everything, no card required.

Open in Code BookOpen in EncoderStart Pro