2026 ICD-10-CM Diagnosis Code A51.41Secondary syphilitic meningitis

ICD-10-CM Codes›A00–B99›A50-A64›A51

ICD-10-CM A51.41
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A51.41 is a billable ICD-10-CM diagnosis code for secondary syphilitic meningitis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Meningitis and Sexually transmitted infections (excluding HIV and hepatitis).

Code Identity

ICD-10-CM Code
A51.41
Billable Status
Yes — Valid for Submission
Code Describes
Secondary syphilitic meningitis
Short Description
Secondary syphilitic meningitis
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 CodeA51.41Secondary syphilitic meningitis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute meningitis
  • Acute secondary syphilitic meningitis
  • Acute syphilitic meningitis
  • Meningitis caused by Spirochaetes
  • Secondary neurosyphilis
  • Secondary syphilis of nervous system
  • Secondary syphilitic meningitis
  • Syphilitic meningitis

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.

    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • syphilitic (late) (tertiary)
        • acute
    • Meningitis(basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
      • syphilitic (late) (tertiary)
        • secondary
    • Syphilis, syphilitic(acquired)
      • meningitis
        • acute (secondary)
    • Syphilis, syphilitic(acquired)
      • secondary (and primary)
        • meningitis (acute)

Clinical ClassificationClinical

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

CCSR NVS001
Meningitis
Default principal diagnosis: inpatient No · outpatient No
CCSR INF010
Sexually transmitted infections (excluding HIV and hepatitis)
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • 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.

Patient EducationClinical

Meningitis

Meningitis is inflammation of the thin tissue that surrounds the brain and spinal cord, called the meninges. There are several types of meningitis. The most common is viral meningitis. You get it when a virus enters the body through the nose or mouth and travels to the brain. Bacterial meningitis is rare but can be deadly.

Read the full article at MedlinePlus

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

Convert A51.41 to ICD-9-CMHistory

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

ICD-9-CM
091.81 Acute syphil meningitis
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 A51.41Overview

Is A51.41 (Other secondary syphilis) a billable code?

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

What is the ICD-9 equivalent of A51.41?

Under the General Equivalence Mappings, secondary syphilitic meningitis converts to ICD-9-CM 091.81 (acute syphil meningitis). 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.