2027 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 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

A51.49 is a billable ICD-10-CM diagnosis code for other secondary syphilitic conditions. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 867 through 869. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 1 closely related codes. 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

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to A51.49: its own notes plus those printed at block A50-A64 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Secondary syphilitic lymphadenopathy
  • Secondary syphilitic myositis

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Block A50-A64 Infections with a predominantly sexual mode of transmission applies to 142 codes
  • nonspecific and nongonococcal urethritis (N34.1)
  • Reiter's disease (M02.3-)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Block A50-A64 Infections with a predominantly sexual mode of transmission applies to 142 codes
  • human immunodeficiency virus [HIV] disease (B20)
From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • carrier or suspected carrier of infectious disease (Z22.-)
  • certain localized infections - see body system-related chapters
  • infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
  • infectious and parasitic diseases specific to the perinatal period (P35-P39)
  • influenza and other acute respiratory infections (J00-J22)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • code to identify resistance to antimicrobial drugs (Z16.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name A51.49, its category, or a range that includes it.

Applicable To 1

These notes mention A51.49.

  • O98.1 Syphilis complicating pregnancy, childbirth and the puerperium
    Conditions in A50-A53 names A50-A53, which includes this code

Excludes1 1

These codes carry an Excludes1 note naming A51.49: they are not reported together with it, unless the two conditions are unrelated.

  • M63 Disorders of muscle in diseases classified elsewhere
    myopathy in secondary syphilis (A51.49)

Excludes2 1

These codes carry an Excludes2 note naming A51.49: its condition is not part of those codes, and both may be reported when the patient has both.

  • Block A65-A69 Other spirochetal diseases
    syphilis (A50-A53) names A50-A53, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About A51.49Overview

What is the ICD-10 code for other secondary syphilitic conditions?

The ICD-10-CM code for other secondary syphilitic conditions is A51.49 (sometimes written as A5149). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

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, 2026 through September 30, 2027.

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, 869, 868, with relative weights from 0.6784 to 2.1855 depending on complications. Higher weights mean higher Medicare reimbursement.

Is A51.49 a CC or MCC?

CMS lists A51.49 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 1 closely related codes in its exclusion list.

Can A51.49 be reported with N34.1?

Not as a rule. The Excludes1 note at block A50-A64, which applies to A51.49, lists "nonspecific and nongonococcal urethritis (N34.1)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).