B43.1 ICD-10-CM Code: Pheomycotic brain abscess

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for B43.1 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 B43.1 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for B43.1

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

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).

Official instructions as workflow

• Excludes2 — not part of B43.1(2 notes)

  Coding workflow: The conditions named in this note are not included in B43.1. 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

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 (5)

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.

• Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), brain (any part) (cystic) (otogenic), pheomycotic (chromomycotic)
• Chromomycosis, brain abscess
• Chromomycosis, cerebral
• Infection, infected, infective (opportunistic), Cladosporium, bantianum (brain abscess)
• Infection, infected, infective (opportunistic), Cladosporium, trichoides (brain abscess)

Don’t confuse B43.1 with…

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

The codes most likely to be picked instead of B43.1 — 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.

• B43.9— Specificity relationship (Review)

  Overlapping diagnoses in the same category.

  Overlapping codes in the same category — the documentation decides which is the more specific fit.

  What moves you there: A record that documents no more than “Chromomycosis, unspecified” takes B43.9; specificity in the record moves it back here.

  Full comparison: B43.1 vs B43.9 →

• 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: B43.1 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: B43.1 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

• No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

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 B43.1 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 Excludes1 note: G07 — Intracranial and intraspinal abscess and granuloma in diseases classified elsewhere.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Code First instruction: M01 — Direct infections of joint in infectious and parasitic diseases classified elsewhere (via B43.-).

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: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 3 MS-DRGs: DRG 867 (MDC 18), DRG 868 (MDC 18), DRG 869 (MDC 18).

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

Clinical classification (AHRQ CCSR):NVS014 — CNS abscess (default); INF004 — Fungal infections.

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 category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (CNS abscess, Fungal infections).

B41.8 — Other forms of paracoccidioidomycosis, B41.9 — Paracoccidioidomycosis, unspecified, B42.0 — Pulmonary sporotrichosis, B42.1 — Lymphocutaneous sporotrichosis, B42.7 — Disseminated sporotrichosis, B42.81 — Cerebral sporotrichosis, B42.82 — Sporotrichosis arthritis, B42.89 — Other forms of sporotrichosis, B42.9 — Sporotrichosis, unspecified, B43.0 — Cutaneous chromomycosis, B43.2 — Subcutaneous pheomycotic abscess and cyst, B43.8 — Other forms of chromomycosis, B43.9 — Chromomycosis, unspecified, B44.0 — Invasive pulmonary aspergillosis, B44.1 — Other pulmonary aspergillosis, B44.2 — Tonsillar aspergillosis, B44.7 — Disseminated aspergillosis, B44.81 — Allergic bronchopulmonary aspergillosis, B44.89 — Other forms of aspergillosis, B44.9 — Aspergillosis, unspecified, +93 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Abscess”; these codes share that main term but sit in a different category of the Tabular List.

A17.81 — Tuberculoma of brain and spinal cord (brain, tuberculous), A18.01 — Tuberculosis of spine (spine), A18.2 — Tuberculous peripheral lymphadenopathy (scrofulous), A18.31 — Tuberculous peritonitis (peritoneum, peritoneal, tuberculous), A48.0 — Gas gangrene (anerobic), A50.59 — Other late congenital syphilis, symptomatic (Dubois), A54.1 — Gonococcal infection of lower genitourinary tract with periurethral and accessory gland abscess (penis, gonococcal), A54.22 — Gonococcal prostatitis (prostate, gonococcal), A54.82 — Gonococcal brain abscess (brain, gonococcal), A57 — Chancroid (phagedenic NOS, chancroid), B65.1 — Schistosomiasis due to Schistosoma mansoni [intestinal schistosomiasis] (bilharziasis), D73.3 — Abscess of spleen (spleen), E06.0 — Acute thyroiditis (thyroid), E23.6 — Other disorders of pituitary gland (pituitary), E27.8 — Other specified disorders of adrenal gland (adrenal), E32.1 — Abscess of thymus (thymus), G06.0 — Intracranial abscess and granuloma (brain), G06.1 — Intraspinal abscess and granuloma (spinal cord), G06.2 — Extradural and subdural abscess, unspecified (subdural), G09 — Sequelae of inflammatory diseases of central nervous system (cerebral, sequelae), +158 more

Contextual Map

Every relationship of B43.1 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 B43.1 with these 2 related codes 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 Excludes1 notes

• G07 — Intracranial and intraspinal abscess and granuloma in diseases classified elsewhere[Excludes1]: “chromomycotic (B43.1)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Code First instructions

• M01 — Direct infections of joint in infectious and parasitic diseases classified elsewhere[Code First](via B43.-): “mycoses (B35-B49)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• NVS014 — CNS abscess[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)
• INF004 — Fungal infections[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• 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

MDC crossing

• 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

• Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), brain (any part) (cystic) (otogenic), pheomycotic (chromomycotic)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Chromomycosis, brain abscess[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Chromomycosis, cerebral[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Infection, infected, infective (opportunistic), Cladosporium, bantianum (brain abscess)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Infection, infected, infective (opportunistic), Cladosporium, trichoides (brain abscess)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

• B43 — Chromomycosis and pheomycotic abscess[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B43.0 — Cutaneous chromomycosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B43.2 — Subcutaneous pheomycotic abscess and cyst[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B43.8 — Other forms of chromomycosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B43.9 — Chromomycosis, unspecified[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

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 B43.1 in its code family, with their registry titles.

• B43 — Chromomycosis and pheomycotic abscess
• B43.0 — Cutaneous chromomycosis
• B43.2 — Subcutaneous pheomycotic abscess and cyst
• B43.8 — Other forms of chromomycosis
• B43.9 — Chromomycosis, unspecified

View all codes in the B43 family