A66.5 ICD-10-CM Code: Gangosa

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for A66.5 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 A66.5 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for A66.5

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 A66.5(2 notes)

  Coding workflow: The conditions named in this note are not included in A66.5. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  CompareA27

  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 (4)

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.

• Gangosa
• Rhinopharyngitis (acute) (subacute), destructive ulcerating
• Rhinopharyngitis (acute) (subacute), mutilans
• Yaws, gangosis, gangosa

Don’t confuse A66.5 with…

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

The codes most likely to be picked instead of A66.5 — 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.

• A66.9— 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 “Yaws, unspecified” takes A66.9; specificity in the record moves it back here.

  Full comparison: A66.5 vs A66.9 →

• A27— 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 leptospirosis adds A27; it is not part of this code and both may be reported when both are documented.

  Full comparison: A66.5 vs A27 →

• A50— 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 syphilis adds A50; it is not part of this code and both may be reported when both are documented.

  Full comparison: A66.5 vs A50 →

• A53— 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 syphilis adds A53; it is not part of this code and both may be reported when both are documented.

  Full comparison: A66.5 vs A53 →

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

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 6 MS-DRGs: DRG 011 (MDC PRE), DRG 012 (MDC PRE), DRG 013 (MDC PRE), DRG 154 (MDC 03), DRG 155 (MDC 03), DRG 156 (MDC 03).

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

Clinical classification (AHRQ CCSR):INF009 — Parasitic, other specified and unspecified 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 category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Parasitic, other specified and unspecified infections).

A59.03 — Trichomonal cystitis and urethritis, A59.09 — Other urogenital trichomoniasis, A59.8 — Trichomoniasis of other sites, A59.9 — Trichomoniasis, unspecified, A65 — Nonvenereal syphilis, A66.0 — Initial lesions of yaws, A66.1 — Multiple papillomata and wet crab yaws, A66.2 — Other early skin lesions of yaws, A66.3 — Hyperkeratosis of yaws, A66.4 — Gummata and ulcers of yaws, A66.6 — Bone and joint lesions of yaws, A66.7 — Other manifestations of yaws, A66.8 — Latent yaws, A66.9 — Yaws, unspecified, A67.0 — Primary lesions of pinta, A67.1 — Intermediate lesions of pinta, A67.2 — Late lesions of pinta, A67.3 — Mixed lesions of pinta, A67.9 — Pinta, unspecified, A68.0 — Louse-borne relapsing fever, +235 more

Same Index main term, other category

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

J31.1 — Chronic nasopharyngitis

Contextual Map

Every relationship of A66.5 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.

Hierarchy

• A00-B99 — Chapter 1: Certain Infectious and Parasitic Diseases (A00-B99) (A00-B99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A65-A69 — Other spirochetal diseases[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Clinical classification (CCSR)

• INF009 — Parasitic, other specified and unspecified infections[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• DRG 011 — TRACHEOSTOMY FOR FACE, MOUTH AND NECK DIAGNOSES OR LARYNGECTOMY WITH MCC[MS-DRG]: “TRACHEOSTOMY FOR FACE, MOUTH AND NECK DIAGNOSES OR LARYNGECTOMY WITH MCC (MDC PRE)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 012 — TRACHEOSTOMY FOR FACE, MOUTH AND NECK DIAGNOSES OR LARYNGECTOMY WITH CC[MS-DRG]: “TRACHEOSTOMY FOR FACE, MOUTH AND NECK DIAGNOSES OR LARYNGECTOMY WITH CC (MDC PRE)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 013 — TRACHEOSTOMY FOR FACE, MOUTH AND NECK DIAGNOSES OR LARYNGECTOMY WITHOUT CC/MCC[MS-DRG]: “TRACHEOSTOMY FOR FACE, MOUTH AND NECK DIAGNOSES OR LARYNGECTOMY WITHOUT CC/MCC (MDC PRE)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 154 — OTHER EAR, NOSE, MOUTH AND THROAT DIAGNOSES WITH MCC[MS-DRG]: “OTHER EAR, NOSE, MOUTH AND THROAT DIAGNOSES WITH MCC (MDC 03)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 155 — OTHER EAR, NOSE, MOUTH AND THROAT DIAGNOSES WITH CC[MS-DRG]: “OTHER EAR, NOSE, MOUTH AND THROAT DIAGNOSES WITH CC (MDC 03)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 156 — OTHER EAR, NOSE, MOUTH AND THROAT DIAGNOSES WITHOUT CC/MCC[MS-DRG]: “OTHER EAR, NOSE, MOUTH AND THROAT DIAGNOSES WITHOUT CC/MCC (MDC 03)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• Pre-MDC[MDC crossing]: “Pre-MDC — 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. 153 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
• MDC 03 — Diseases and Disorders of the Ear, Nose, Mouth and Throat[MDC crossing]: “Diseases and Disorders of the Ear, Nose, Mouth and Throat — 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. 5,147 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Gangosa[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Rhinopharyngitis (acute) (subacute), destructive ulcerating[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Rhinopharyngitis (acute) (subacute), mutilans[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Yaws, gangosis, gangosa[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (10)

• A66 — Yaws[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A66.0 — Initial lesions of yaws[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A66.1 — Multiple papillomata and wet crab yaws[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A66.2 — Other early skin lesions of yaws[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A66.3 — Hyperkeratosis of yaws[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A66.4 — Gummata and ulcers of yaws[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A66.6 — Bone and joint lesions of yaws[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A66.7 — Other manifestations of yaws[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 2 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

Nearest Codes in This Family

Official ICD-10-CM classifications closest to A66.5 in its code family, with their registry titles.

• A66 — Yaws
• A66.0 — Initial lesions of yaws
• A66.1 — Multiple papillomata and wet crab yaws
• A66.2 — Other early skin lesions of yaws
• A66.3 — Hyperkeratosis of yaws
• A66.4 — Gummata and ulcers of yaws
• A66.6 — Bone and joint lesions of yaws
• A66.7 — Other manifestations of yaws
• A66.8 — Latent yaws
• A66.9 — Yaws, unspecified

View all codes in the A66 family