ICD-10-CM 2027
ICD-10 code for primary lesion
From the official ICD-10-CM alphabetic index entry “Lesion (s) (nontraumatic) › primary”. Page updated September 29, 2026.
About coding primary lesion
The ICD-10-CM code for primary lesion is A51.0 (Primary genital syphilis). The official index lists 3 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on A51.0.
Within A51 (early syphilis), A51.0 is specifically for primary genital syphilis. Related codes cover primary anal syphilis (A51.1), primary syphilis of other sites (A51.2), secondary syphilis of skin and mucous membranes (A51.3), other secondary syphilis (A51.4), latent (A51.5) and unspecified (A51.9).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 727 (Inflammation of the Male Reproductive System with MCC, relative weight 1.37), DRG 728 (Inflammation of the Male Reproductive System without MCC, relative weight 0.8224), DRG 742 (Uterine and Adnexa Procedures for Non-Malignancy with CC/MCC, relative weight 1.8456), DRG 743 (Uterine and Adnexa Procedures for Non-Malignancy without CC/MCC, relative weight 1.2974), DRG 757 (Infections, Female Reproductive System with MCC, relative weight 1.4649), DRG 758 (Infections, Female Reproductive System with CC, relative weight 0.9908) and 1 more, in MDC 12 (Diseases and Disorders of the Male Reproductive System) and MDC 13 (Diseases and Disorders of the Female Reproductive System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
More specific primary lesion codes (official index)
Common questions about primary lesion ICD-10 codes
What is the ICD-10 code for primary lesion?
- A51.0 — Primary genital syphilis. More specific codes apply when the documentation supports them: A67.0, A67.0, A66.0.
What is the ICD-10 code for carate primary lesion?
- A67.0 — Primary lesions of pinta.
What is the ICD-10 code for pinta primary lesion?
- A67.0 — Primary lesions of pinta.
What is the ICD-10 code for yaws primary lesion?
- A66.0 — Initial lesions of yaws.
Is A51.0 billable?
- Yes. A51.0 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can A51.0 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict A51.0 as a principal diagnosis.
Is A51.0 a CC or MCC?
- No. A51.0 is neither a CC nor an MCC under MS-DRG v44.0.