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B45.3 ICD-10-CM Code: Osseous cryptococcosis

B45.3 maps to CMS-HCC V28 6. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · HCC coding software

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

B45.3

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

Osseous cryptococcosis

A fungal infection of the bones caused by Cryptococcus, which can cause bone pain and structural damage.

Buddy the Bee presenting code insight

Buddy Insight

Osseous cryptococcosis is a rare manifestation of disseminated Cryptococcus infection involving bone, typically presenting with lytic lesions that can mimic metastatic disease or primary bone tumors.

CMS-HCC V28

HCC 6

Code-level coefficient reference

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
B45Cryptococcosis
B45.3Osseous cryptococcosis

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for B45.3 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for B45.3 in this effective period.

Related Child Codes

Official
B45.0Pulmonary cryptococcosis
B45.1Cerebral cryptococcosis
B45.2Cutaneous cryptococcosis
B45.7Disseminated cryptococcosis
B45.8Other forms of cryptococcosis

Includes

Official

ICD-10-CM does not list Includes notes for B45.3 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for B45.3 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for B45.3 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for B45.3 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for B45.3 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Bone biopsy with culture or histopathology confirming Cryptococcus
Imaging showing lytic bone lesions (radiograph, CT, or MRI)
Specific bone(s) affected documented with laterality
Evaluation for disseminated disease documented (serum antigen, lumbar puncture, chest imaging)

MEAT Support

HCC Buddy guidance
Bone biopsy with culture or histopathology confirming Cryptococcus
Imaging showing lytic bone lesions (radiograph, CT, or MRI)
Specific bone(s) affected documented with laterality
Evaluation for disseminated disease documented (serum antigen, lumbar puncture, chest imaging)

Audit Caution

HCC Buddy guidance
Misdiagnosing as metastatic bone disease based on imaging alone without obtaining tissue confirmation
Not evaluating for concurrent central nervous system disease when bone involvement suggests dissemination
Using generic osteomyelitis codes instead of the specific fungal infection code

Common Mistakes

HCC Buddy guidance
B45.7 (Disseminated cryptococcosis) - if bone involvement is part of multi-organ disease, consider using the disseminated code
M86.9 (Osteomyelitis, unspecified) - bacterial osteomyelitis; fungal bone infection requires specific B45.3 code
C79.51 (Secondary malignant neoplasm of bone) - lytic lesions from cryptococcosis can mimic metastatic disease on imaging

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 B45.3 an HCC code?

Yes. B45.3 (Osseous 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: B45.3 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
B45.3
Description
Osseous 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 B45.3 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for B45.3

For B45.3 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 B45.3 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

B45.3 is the ICD-10-CM diagnosis code for osseous cryptococcosis. A fungal infection of the bones caused by Cryptococcus, which can cause bone pain and structural damage. B45.3 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, B45.3 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 B45.3; use the applicable model and payment year when reviewing the V28 mapping. 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. 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 rare manifestation of cryptococcosis; ensure documentation clearly indicates bone/osseous involvement. Because B45.3 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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 B45.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •This is a rare manifestation of cryptococcosis; ensure documentation clearly indicates bone/osseous involvement
  • •Investigate for disseminated disease and immunocompromised status, as osseous involvement suggests systemic infection

Clinical Significance

Osseous cryptococcosis is a rare manifestation of disseminated Cryptococcus infection involving bone, typically presenting with lytic lesions that can mimic metastatic disease or primary bone tumors. Its presence strongly suggests systemic dissemination and warrants thorough evaluation for central nervous system and pulmonary involvement.

Documentation Requirements

  • ✓Bone biopsy with culture or histopathology confirming Cryptococcus
  • ✓Imaging showing lytic bone lesions (radiograph, CT, or MRI)
  • ✓Specific bone(s) affected documented with laterality
  • ✓Evaluation for disseminated disease documented (serum antigen, lumbar puncture, chest imaging)
  • ✓Immunocompromised status documented

Commonly Confused Codes

  • •B45.7 (Disseminated cryptococcosis) - if bone involvement is part of multi-organ disease, consider using the disseminated code
  • •M86.9 (Osteomyelitis, unspecified) - bacterial osteomyelitis; fungal bone infection requires specific B45.3 code
  • •C79.51 (Secondary malignant neoplasm of bone) - lytic lesions from cryptococcosis can mimic metastatic disease on imaging

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└B45.3Osseous cryptococcosis
└B45.3Osseous cryptococcosis

Because B45.3 maps to an HCC category, the documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment.

B45.3 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 B45.3. 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 B45.3 in HCC Buddy

Open B45.3 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.

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