A66.4 ICD-10-CM Code: Gummata and ulcers of yaws
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FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Other spirochetal diseases (A65-A69)
A66.4
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceGummata and ulcers of yaws
This condition involves the development of gummas (soft, rubbery growths) and ulcers (open sores) caused by yaws, a tropical infection spread through skin contact. These lesions typically appear on the skin and can be disfiguring if left untreated.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
00
RAF 0
Code Trumping
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Code Book Path
Inclusion Terms
Official- Gummatous frambeside
- Nodular late yaws (ulcerated)
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for A66.4 in this effective period.
Related Child Codes
Includes
Official- bouba
- frambesia (tropica)
- pian
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for A66.4 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for A66.4 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for A66.4 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for A66.4 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is A66.4 an HCC code?
No. A66.4 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
A66.4 is the ICD-10-CM diagnosis code for gummata and ulcers of yaws. This condition involves the development of gummas (soft, rubbery growths) and ulcers (open sores) caused by yaws, a tropical infection spread through skin contact. These lesions typically appear on the skin and can be disfiguring if left untreated. A66.4 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering other spirochetal diseases (a65-a69).
A66.4 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Yaws (caused by Treponema pallidum subspecies pertenue) is a reportable disease in most jurisdictions; verify local reporting requirements before finalizing the code.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for A66.4 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Yaws (caused by Treponema pallidum subspecies pertenue) is a reportable disease in most jurisdictions; verify local reporting requirements before finalizing the code
- •Ensure documentation specifies the presence of gummata and/or ulcers to justify code A66.4 rather than other yaws manifestations (A66.0-A66.3, A66.8-A66.9)