ICD-10 Code A66 – Yaws (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A66 – Yaws
What it is
Yaws is a chronic infectious disease caused by Treponema pallidum subspecies pertenue. It mainly affects skin, bone, and cartilage, and is seen in tropical regions.
Clinical signs
Early disease often begins with a skin lesion that may be papillomatous, ulcerated, or crusted. Later stages can involve bone pain, deformity, or destructive skin and soft-tissue changes.
When to use this code
Use A66 when documentation clearly identifies yaws or a yaws-related infection. This code applies to confirmed clinical diagnoses, including early or late manifestations, when the record states yaws rather than a nonspecific treponemal infection.
Do not use for
Do not use this code for syphilis or other treponemal diseases that are separately documented. If the provider only notes a skin ulcer, rash, or bone lesion without naming yaws, check documentation.
Coding tip
Code A66 only when the clinician documents yaws explicitly; otherwise, query for the specific diagnosis.