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B49 ICD-10-CM Code: Unspecified mycosis

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 inclusion term · 2 Excludes2

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 867 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH MCC (MDC 18)
  • MS-DRG 868 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH CC (MDC 18)
  • MS-DRG 869 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITHOUT CC/MCC (MDC 18)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for B49 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 B49 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Fungemia NOS

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from B35-B49

Coder workflow for B49

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

Before you code B49

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, B49 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).

    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 — B49 is appropriate when the documentation goes no further.

Consider B49. 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 B49(2 notes)

    Coding workflow: The conditions named in this note are not included in B49. 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

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the subcategory for a sibling that names the missing detail.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

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.

Code Overview

Unspecified mycosis is a billable ICD-10-CM diagnosis code (B49).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (19)

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.

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 B49 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 2 Code First instructions across 2 chapters: J99 — Respiratory disorders in diseases classified elsewhere, M01 — Direct infections of joint in infectious and parasitic diseases classified elsewhere.

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 2 clinically related codes on its CMS exclusion list.

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):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.

B48.3 — Geotrichosis

Same clinical category (CCSR)

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

B45.9 — Cryptococcosis, unspecified, 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, B47.9 — Mycetoma, unspecified, B48.0 — Lobomycosis, B48.1 — Rhinosporidiosis, B48.2 — Allescheriasis, B48.3 — Geotrichosis, B48.4 — Penicillosis, B48.8 — Other specified mycoses, B59 — Pneumocystosis, P37.5 — Neonatal candidiasis, +86 more

Same Index main term, other category

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

B37.32 — Chronic candidiasis of vulva and vagina (vagina, vaginitis, chronic), B37.5 — Candidal meningitis (candidal), B37.7 — Candidal sepsis (candida), B37.84 — Candidal otitis externa (ear, in, moniliasis), B38.4 — Coccidioidomycosis meningitis (in, coccidioidomycosis), B42.81 — Cerebral sporotrichosis (sporotrichosis), B42.82 — Sporotrichosis arthritis (in, sporotrichosis), B44.89 — Other forms of aspergillosis (ear, in, aspergillosis), B45.1 — Cerebral cryptococcosis (cryptococcal), B48.8 — Other specified mycoses (specified NEC), B56.9 — African trypanosomiasis, unspecified (in, African trypanosomiasis), B57.41 — Meningitis in Chagas' disease (in, Chagas' disease), B58.82 — Toxoplasma myositis (in, toxoplasmosis), B65.2 — Schistosomiasis due to Schistosoma japonicum (due to, S. japonicum), B65.9 — Schistosomiasis, unspecified (in, bilharziasis), B69.81 — Myositis in cysticercosis (in, cysticercosis), B72 — Dracunculiasis (in, dracontiasis), B74.9 — Filariasis, unspecified (chylous), B75 — Trichinellosis (in, trichinellosis), B76.1 — Necatoriasis (due to, Necator americanus), +399 more

Contextual Map

Every relationship of B49 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 B49 with these 4 related codes in Claim Check

Hierarchy

Excludes2

Index manifestation

Referenced by Code First instructions

Clinical classification (CCSR)

MS-DRG Grouper

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 (19)

  • Arthritis, arthritic (acute) (chronic) (nonpyogenic) (subacute), in (due to), mycosis NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Arthritis, arthritic (acute) (chronic) (nonpyogenic) (subacute), mycotic NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Bronchomycosis NOS[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Cough (affected) (epidemic) (nervous), tea taster's[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Diarrhea, diarrheal (disease) (infantile) (inflammatory), mycotic NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Disease, diseased, fungus NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Disease, diseased, mycotic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fungemia NOS[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • and 11 more

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

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "B49 — Unspecified mycosis." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/b49-unspecified-mycosis

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Unspecified mycosis

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.