2026 ICD-10-CM Diagnosis Code A66.0Initial lesions of yaws

ICD-10-CM Codes›A00–B99›A65-A69›A66

ICD-10-CM A66.0
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A66.0 is a billable ICD-10-CM diagnosis code for initial lesions of yaws. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 606 through 607. Coders also document this condition as initial frambesial ulcer. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections.

Code Identity

ICD-10-CM Code
A66.0
Billable Status
Yes — Valid for Submission
Code Describes
Initial lesions of yaws
Short Description
Initial lesions of yaws
Same as the full description in the CMS dataset.
Parent Code
A66
Yaws

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA65-A69Other spirochetal diseases
CategoryA66Yaws
This CodeA66.0Initial lesions of yaws

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Initial frambesial ulcer
  • Initial lesion of yaws

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Chancre of yaws
  • Frambesia, initial or primary
  • Initial frambesial ulcer
  • Mother yaw

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Chancre(any genital site) (hard) (hunterian) (mixed) (primary) (seronegative) (seropositive) (syphilitic)
      • of
        • yaws
    • Chancre(any genital site) (hard) (hunterian) (mixed) (primary) (seronegative) (seropositive) (syphilitic)
      • yaws
    • Frambesia, frambesial(tropica)
      • initial lesion or ulcer
    • Frambesia, frambesial(tropica)
      • primary
    • Lesion(s) (nontraumatic)
      • primary
        • yaws
    • Mother yaw
    • Ulcer, ulcerated, ulcerating, ulceration, ulcerative
      • frambesial, initial
    • Yaws
      • chancre
    • Yaws
      • initial lesions
    • Yaws
      • mother

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INF009
Parasitic, other specified and unspecified infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Yaws

    a systemic non-venereal infection of the tropics caused by treponema pallidum subspecies pertenue.

  • Treponema pallidum

    the causative agent of venereal and non-venereal syphilis as well as yaws.

  • Early Yaws

    early yaws includes primary and secondary stages of yaws, endemic tropical treponemal nonvenereal infection: development of initial lesion at inoculation site followed by widespread dissemination of treponemes and generalized secondary granulomatous lesions that may relapse repeatedly.

  • Late Yaws

    late yaws is the tertiary, non-contagious stage of yaws, endemic tropical treponemal nonvenereal infection. late yaws is characterized by destructive and deforming lesions of the skin, bones, and joints.

  • Yaws

    an endemic, infectious, nonvenereal disease in humans that presents mainly in children younger than 15 years. the disease occurs primarily in warm, humid, tropical areas of africa, asia, south america, and oceania, among poor rural populations where conditions of overcrowding and poor sanitation prevail. infection with treponema pertenue, a subspecies of treponema pallidum, causes the disease.

Patient EducationClinical

Bacterial Infections

Bacteria are tiny organisms (living things) that have only one cell. Under a microscope, they look like balls, rods, or spirals. They can be found almost everywhere on Earth. There are lots of bacteria in and on your body. In fact, your body has about 10 times more bacteria cells than human cells.

The full article covers:

  • What are bacteria?
  • How do bacterial infections spread?
  • What are the treatments for bacterial infections?
  • Can bacterial infections be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert A66.0 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
102.0 Initial lesions yaws
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About A66.0Overview

Is A66.0 (Yaws) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report initial lesions of yaws on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does A66.0 group to?

When initial lesions of yaws is the principal diagnosis on an inpatient stay, it groups to MS-DRG 606, 607, with relative weights from 0.9064 to 1.5132 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of A66.0?

Under the General Equivalence Mappings, initial lesions of yaws converts to ICD-9-CM 102.0 (initial lesions yaws). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.