ICD-10-CM 2027
ICD-10 code for secondary syphilis
From the official ICD-10-CM alphabetic index entry “Syphilis, syphilitic (acquired) › secondary (and primary)”. Page updated September 29, 2026.
About coding secondary syphilis
The ICD-10-CM code for secondary syphilis is A51.49 (Other secondary syphilitic conditions). The official index lists 19 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on A51.49.
Within A51.4, choose A51.49 (Other secondary syphilitic conditions) only when documentation doesn't support a more specific option: secondary syphilitic meningitis (A51.41), secondary syphilitic female pelvic disease (A51.42), secondary syphilitic oculopathy (A51.43), secondary syphilitic nephritis (A51.44), secondary syphilitic hepatitis (A51.45) and secondary syphilitic osteopathy (A51.46).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 867 (Other Infectious and Parasitic Diseases Diagnoses with MCC, relative weight 2.1859), DRG 868 (Other Infectious and Parasitic Diseases Diagnoses with CC, relative weight 1.0235) and DRG 869 (Other Infectious and Parasitic Diseases Diagnoses without CC/MCC, relative weight 0.6787), in MDC 18 (Infectious and Parasitic Diseases, Systemic or Unspecified Sites), 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 secondary syphilis codes (official index)
- adenopathy A51.49 — Other secondary syphilitic conditions
- anus A51.39 — Other secondary syphilis of skin
- bone A51.46 — Secondary syphilitic osteopathy
- chorioretinitis, choroiditis A51.43 — Secondary syphilitic oculopathy
- hepatitis A51.45 — Secondary syphilitic hepatitis
- liver A51.45 — Secondary syphilitic hepatitis
- lymphadenitis A51.49 — Other secondary syphilitic conditions
- meningitis (acute) A51.41 — Secondary syphilitic meningitis
- mouth A51.39 — Other secondary syphilis of skin
- mucous membranes A51.39 — Other secondary syphilis of skin
- periosteum, periostitis A51.46 — Secondary syphilitic osteopathy
- pharynx A51.39 — Other secondary syphilis of skin
- relapse (treated, untreated) A51.49 — Other secondary syphilitic conditions
- skin A51.39 — Other secondary syphilis of skin
- specified form NEC A51.49 — Other secondary syphilitic conditions
- tonsil A51.39 — Other secondary syphilis of skin
- ulcer A51.39 — Other secondary syphilis of skin
- viscera NEC A51.49 — Other secondary syphilitic conditions
- vulva A51.39 — Other secondary syphilis of skin
Common questions about secondary syphilis ICD-10 codes
What is the ICD-10 code for secondary syphilis?
- A51.49 — Other secondary syphilitic conditions. More specific codes apply when the documentation supports them: A51.49, A51.39, A51.46, A51.43 and others below.
What is the ICD-10 code for adenopathy secondary syphilis?
- A51.49 — Other secondary syphilitic conditions.
What is the ICD-10 code for anus secondary syphilis?
- A51.39 — Other secondary syphilis of skin.
What is the ICD-10 code for bone secondary syphilis?
- A51.46 — Secondary syphilitic osteopathy.
What is the ICD-10 code for hepatitis secondary syphilis?
- A51.45 — Secondary syphilitic hepatitis.
What is the ICD-10 code for liver secondary syphilis?
- A51.45 — Secondary syphilitic hepatitis.
What is the ICD-10 code for lymphadenitis secondary syphilis?
- A51.49 — Other secondary syphilitic conditions.
Is A51.49 billable?
- Yes. A51.49 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can A51.49 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict A51.49 as a principal diagnosis.
Is A51.49 a CC or MCC?
- A51.49 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.