B45.9 ICD-10-CM Code: Cryptococcosis, unspecified

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for B45.9 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on B45.9 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for B45.9

MedCoder structured workflow — derived from this code’s own official record

Before you code B45.9

1. Unspecified does not mean incorrect. When the record gives no greater specificity, B45.9 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

   ReviewB45.0, B45.1, B45.2, B45.3, B45.7, B45.8

   See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

Choose the right path

1. Does the record document the detail a more specific sibling code needs?
   Yes → Review the specific siblings in this subcategory.
   No → Continue — B45.9 is appropriate when the documentation goes no further.

   ReviewB45.0, B45.1, B45.2, B45.3, B45.7, B45.8

Consider B45.9. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Any detail beyond this code’s title

What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

• Excludes2 — not part of B45.9(2 notes)

  Coding workflow: The conditions named in this note are not included in B45.9. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  CompareJ67, C84.0

  See the official tabular notes · Guidelines I.A.12.b

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (1)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Cryptococcosis, cryptococcus (infection) (neoformans)

Don’t confuse B45.9 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of B45.9 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• J67— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of hypersensitivity pneumonitis due to organic dust adds J67; it is not part of this code and both may be reported when both are documented.

  Full comparison: B45.9 vs J67 →

• C84.0— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of mycosis fungoides adds C84.0; it is not part of this code and both may be reported when both are documented.

  Full comparison: B45.9 vs C84.0 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name B45.9 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Code First instruction: M01 — Direct infections of joint in infectious and parasitic diseases classified elsewhere (via B45.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 12 clinically related codes on its CMS exclusion list. Does not count toward severity when the stay groups to DRGs 974-976 (HIV with Major Related Condition).

Named in the grouper logic of 8 MS-DRGs: DRG 791 (MDC 15), DRG 793 (MDC 15), DRG 867 (MDC 18), DRG 868 (MDC 18), DRG 869 (MDC 18), DRG 974 (MDC 25), DRG 975 (MDC 25), DRG 976 (MDC 25).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):INF004 — Fungal infections (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

B45.0 — Pulmonary cryptococcosis, B45.2 — Cutaneous cryptococcosis, B45.3 — Osseous cryptococcosis, B45.7 — Disseminated cryptococcosis, B45.8 — Other forms of cryptococcosis, B48.3 — Geotrichosis, B49 — Unspecified mycosis, B92 — Sequelae of leprosy, B94.2 — Sequelae of viral hepatitis, B94.8 — Sequelae of other specified infectious and parasitic diseases, B94.9 — Sequelae of unspecified infectious and parasitic disease

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Opportunistic Infections) for risk-adjusted payment.

B44.2 — Tonsillar aspergillosis, B44.7 — Disseminated aspergillosis, B44.89 — Other forms of aspergillosis, B44.9 — Aspergillosis, unspecified, B45.0 — Pulmonary cryptococcosis, B45.1 — Cerebral cryptococcosis, B45.2 — Cutaneous cryptococcosis, B45.3 — Osseous cryptococcosis, B45.7 — Disseminated cryptococcosis, B45.8 — Other forms of cryptococcosis, B46.0 — Pulmonary mucormycosis, B46.1 — Rhinocerebral mucormycosis, B46.2 — Gastrointestinal mucormycosis, B46.3 — Cutaneous mucormycosis, B46.4 — Disseminated mucormycosis, B46.5 — Mucormycosis, unspecified, B46.8 — Other zygomycoses, B46.9 — Zygomycosis, unspecified, B48.4 — Penicillosis, B48.8 — Other specified mycoses, +16 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Fungal infections).

B44.7 — Disseminated aspergillosis, B44.81 — Allergic bronchopulmonary aspergillosis, B44.89 — Other forms of aspergillosis, B44.9 — Aspergillosis, unspecified, B45.0 — Pulmonary cryptococcosis, B45.1 — Cerebral cryptococcosis, B45.2 — Cutaneous cryptococcosis, B45.3 — Osseous cryptococcosis, B45.7 — Disseminated cryptococcosis, B45.8 — Other forms of cryptococcosis, B46.0 — Pulmonary mucormycosis, B46.1 — Rhinocerebral mucormycosis, B46.2 — Gastrointestinal mucormycosis, B46.3 — Cutaneous mucormycosis, B46.4 — Disseminated mucormycosis, B46.5 — Mucormycosis, unspecified, B46.8 — Other zygomycoses, B46.9 — Zygomycosis, unspecified, B47.0 — Eumycetoma, B47.1 — Actinomycetoma, +86 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

HIV Screening Test

Contextual Map

Every relationship of B45.9 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run B45.9 with this related code in Claim Check

Hierarchy

• A00-B99 — Chapter 1: Certain Infectious and Parasitic Diseases (A00-B99) (A00-B99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B35-B49 — Mycoses[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Code First instructions

• M01 — Direct infections of joint in infectious and parasitic diseases classified elsewhere[Code First](via B45.-): “mycoses (B35-B49)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• INF004 — Fungal infections[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

Risk adjustment (CMS-HCC)

• HCC 6 — Opportunistic Infections [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC). Not counted when the stay groups to DRGs 974-976 (HIV with Major Related Condition).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 791 — PREMATURITY WITH MAJOR PROBLEMS[MS-DRG]: “PREMATURITY WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS[MS-DRG]: “FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 867 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH MCC[MS-DRG]: “OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH MCC (MDC 18)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 868 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH CC[MS-DRG]: “OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH CC (MDC 18)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 869 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITHOUT CC/MCC[MS-DRG]: “OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITHOUT CC/MCC (MDC 18)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 974 — HIV WITH MAJOR RELATED CONDITION WITH MCC[MS-DRG]: “HIV WITH MAJOR RELATED CONDITION WITH MCC (MDC 25)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 975 — HIV WITH MAJOR RELATED CONDITION WITH CC[MS-DRG]: “HIV WITH MAJOR RELATED CONDITION WITH CC (MDC 25)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• and 1 more

MDC crossing

• MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2026
• MDC 18 — Infectious and Parasitic Diseases, Systemic or Unspecified Sites[MDC crossing]: “Infectious and Parasitic Diseases, Systemic or Unspecified Sites — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 1 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Cryptococcosis, cryptococcus (infection) (neoformans)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

• B45 — Cryptococcosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B45.0 — Pulmonary cryptococcosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B45.1 — Cerebral cryptococcosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B45.2 — Cutaneous cryptococcosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B45.3 — Osseous cryptococcosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B45.7 — Disseminated cryptococcosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B45.8 — Other forms of cryptococcosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Change history

• FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Risk adjustment Official source data

2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to B45.9 in its code family, with their registry titles.

• B45 — Cryptococcosis
• B45.0 — Pulmonary cryptococcosis
• B45.1 — Cerebral cryptococcosis
• B45.2 — Cutaneous cryptococcosis
• B45.3 — Osseous cryptococcosis
• B45.7 — Disseminated cryptococcosis
• B45.8 — Other forms of cryptococcosis

View all codes in the B45 family