2026 ICD-10-CM Diagnosis Code A50.43Late congenital syphilitic polyneuropathy

ICD-10-CM Codes›A00–B99›A50-A64›A50

ICD-10-CM A50.43
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A50.43 is a billable ICD-10-CM diagnosis code for late congenital syphilitic polyneuropathy. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). Coders also document this condition as bacterial infection of peripheral nerve. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Perinatal infections, Polyneuropathies, and Sexually transmitted infections (excluding HIV and hepatitis).

Code Identity

ICD-10-CM Code
A50.43
Billable Status
Yes — Valid for Submission
Code Describes
Late congenital syphilitic polyneuropathy
Short Description
Late congenital syphilitic polyneuropathy
Same as the full description in the CMS dataset.
Parent Code
A50.4
Late congenital neurosyphilis [juvenile neurosyphilis]

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA50-A64Infections with a predominantly sexual mode of transmission
CategoryA50Congenital syphilis
This CodeA50.43Late congenital syphilitic polyneuropathy

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bacterial infection of peripheral nerve
  • Late congenital syphilis
  • Late congenital syphilitic polyneuropathy
  • Syphilitic polyneuropathy

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.

    • Polyneuropathy(peripheral)
      • in (due to)
        • syphilis (late)
          • congenital
    • Polyneuropathy(peripheral)
      • syphilitic (late)
        • congenital

Clinical ClassificationClinical

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

CCSR PNL009
Perinatal infections
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR NVS015
Polyneuropathies
Default principal diagnosis: inpatient No · outpatient No
CCSR INF010
Sexually transmitted infections (excluding HIV and hepatitis)
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Peripheral Nerve Disorders

Nerves are like wires that carry messages back and forth between your brain and your body. Your peripheral nerves branch off from your brain and spinal cord and connect to all parts of your body, including your muscles and organs.

The full article covers:

  • What are peripheral nerves?
  • What are peripheral nerve disorders?
  • What causes peripheral nerve disorders?
  • What are the symptoms of peripheral nerve disorders?
  • How are peripheral nerve disorders diagnosed?
  • What are the treatments for peripheral nerve disorders?
  • Can peripheral nerve disorders be prevented?

Read the full article at MedlinePlus

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

Convert A50.43 to ICD-9-CMHistory

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

ICD-9-CM
090.40 Juvenile neurosyph NOS
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 A50.43Overview

Is A50.43 (Late congenital neurosyphilis [juvenile neurosyphilis]) a billable code?

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

What is the ICD-9 equivalent of A50.43?

Under the General Equivalence Mappings, late congenital syphilitic polyneuropathy converts to ICD-9-CM 090.40 (juvenile neurosyph NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.