2026 ICD-10-CM Diagnosis Code A51.49Other secondary syphilitic conditions

ICD-10-CM Codes›A00–B99›A50-A64›A51

ICD-10-CM A51.49
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A51.49 is a billable ICD-10-CM diagnosis code for other secondary syphilitic conditions. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 867 through 869. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Sexually transmitted infections (excluding HIV and hepatitis).

Code Identity

ICD-10-CM Code
A51.49
Billable Status
Yes — Valid for Submission
Code Describes
Other secondary syphilitic conditions
Short Description
Other secondary syphilitic conditions
Same as the full description in the CMS dataset.
Parent Code
A51.4
Other secondary syphilis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA50-A64Infections with a predominantly sexual mode of transmission
CategoryA51Early syphilis
This CodeA51.49Other secondary syphilitic conditions

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Arthritis caused by Spirochaetales
  • Gastritis due to secondary syphilis
  • Infection of colon caused by Spirochaetes
  • Infectious synovitis
  • Infective proctitis
  • Nail dystrophy due to secondary syphilis
  • Proctocolitis
  • Proctocolitis due to secondary syphilis
  • Secondary syphilis
  • Secondary syphilis of digestive system
  • Secondary syphilis of musculoskeletal system
  • Secondary syphilis of nervous system
  • Secondary syphilis of synovium
  • Secondary syphilis of viscera
  • Secondary syphilis relapse
  • Secondary syphilis, relapse
  • Secondary syphilitic adenopathy
  • Syphilis of synovium

Tabular List NotesGuidance

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

Inclusion Terms

  • Secondary syphilitic lymphadenopathy
  • Secondary syphilitic myositis

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.

    • Adenopathy(lymph gland)
      • syphilitic (secondary)
    • Lymphadenitis
      • syphilitic (early) (secondary)
    • Lymphadenopathy(generalized)
      • syphilitic (early) (secondary)
    • Myositis
      • in (due to)
        • syphilis
          • secondary
    • Syphilis, syphilitic(acquired)
      • adenopathy (secondary)
    • Syphilis, syphilitic(acquired)
      • early
        • symptomatic
          • secondary
            • relapse (treated, untreated)
    • Syphilis, syphilitic(acquired)
      • lymph gland (early) (secondary)
    • Syphilis, syphilitic(acquired)
      • lymphadenitis (secondary)
    • Syphilis, syphilitic(acquired)
      • secondary (and primary)
    • Syphilis, syphilitic(acquired)
      • secondary (and primary)
        • adenopathy
    • Syphilis, syphilitic(acquired)
      • secondary (and primary)
        • lymphadenitis
    • Syphilis, syphilitic(acquired)
      • secondary (and primary)
        • relapse (treated, untreated)
    • Syphilis, syphilitic(acquired)
      • secondary (and primary)
        • specified form NEC
    • Syphilis, syphilitic(acquired)
      • secondary (and primary)
        • viscera NEC
    • Syphilis, syphilitic(acquired)
      • viscera (abdominal) (late)
        • secondary

Clinical ClassificationClinical

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

CCSR INF010
Sexually transmitted infections (excluding HIV and hepatitis)
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Proctocolitis

    inflammation of the rectum and the distal portion of the colon.

  • Secondary Syphilis

    the secondary stage of syphilis typically that is characterized by generalized rash (including palms and soles), mucocutaneous lesions, and lymphadenopathy. it usually begins one to two months after the primary stage.

  • Proctocolitis

    inflammation of the rectum and colon.

Patient EducationClinical

Syphilis

Syphilis is a sexually transmitted infection (STI) caused by bacteria. It infects the genital area, lips, mouth, or anus of both men and women. You usually get syphilis from sexual contact with someone who has it. It can also pass from mother to baby during pregnancy.

Read the full article at MedlinePlus

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

Convert A51.49 to ICD-9-CMHistory

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

ICD-9-CM
091.4 Syphilitic adenopathy
Approximate The match is approximate rather than exact.
ICD-9-CM
091.69 Second syph viscera NEC
Approximate The match is approximate rather than exact.
ICD-9-CM
091.7 Second syphilis relapse
Approximate The match is approximate rather than exact.
ICD-9-CM
091.89 Secondary syphilis NEC
Approximate The match is approximate rather than exact.

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 A51.49Overview

Is A51.49 (Other secondary syphilis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other secondary syphilitic conditions on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does A51.49 group to?

When other secondary syphilitic conditions is the principal diagnosis on an inpatient stay, it groups to MS-DRG 867, 868, 869, with relative weights from 0.7297 to 2.0932 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of A51.49?

Under the General Equivalence Mappings, other secondary syphilitic conditions converts to ICD-9-CM 091.4 (syphilitic adenopathy), 091.69 (second syph viscera NEC), and 091.7 (second syphilis relapse). The mapping is approximate, so confirm the match fits the documentation.

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.