2026 ICD-10-CM Diagnosis Code A50.40Late congenital neurosyphilis, unspecified

ICD-10-CM Codes›A00–B99›A50-A64›A50

ICD-10-CM A50.40
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A50.40 is a billable ICD-10-CM diagnosis code for late congenital neurosyphilis, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). Coders also document this condition as gummatous neurosyphilis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Perinatal infections and Sexually transmitted infections (excluding HIV and hepatitis).

Code Identity

ICD-10-CM Code
A50.40
Billable Status
Yes — Valid for Submission
Code Describes
Late congenital neurosyphilis, unspecified
Short Description
Late congenital neurosyphilis, unspecified
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 CodeA50.40Late congenital neurosyphilis, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Gummatous neurosyphilis
  • Late congenital neurosyphilis
  • Neurosyphilis
  • Neurosyphilitic tic disorder
  • Secondary neurosyphilis
  • Secondary syphilis of nervous system
  • Syphilitic gumma
  • Syphilitic gumma of central nervous system

Tabular List NotesGuidance

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

Inclusion Terms

  • Juvenile neurosyphilis NOS

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.

    • Neurosyphilis(arrested) (early) (gumma) (late) (latent) (recurrent) (relapse)
      • congenital
    • Neurosyphilis(arrested) (early) (gumma) (late) (latent) (recurrent) (relapse)
      • juvenile (asymptomatic) (meningeal)
    • Syphilis, syphilitic(acquired)
      • central nervous system (late) (recurrent) (relapse) (tertiary)
        • congenital
    • Syphilis, syphilitic(acquired)
      • central nervous system (late) (recurrent) (relapse) (tertiary)
        • juvenile

Clinical ClassificationClinical

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

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

Clinical InformationClinical

  • Neurosyphilis

    infections of the central nervous system caused by treponema pallidum which present with a variety of clinical syndromes. the initial phase of infection usually causes a mild or asymptomatic meningeal reaction. the meningovascular form may present acutely as brain infarction. the infection may also remain subclinical for several years. late syndromes include general paresis; tabes dorsalis; meningeal syphilis; syphilitic optic atrophy; and spinal syphilis. general paresis is characterized by progressive dementia; dysarthria; tremor; myoclonus; seizures; and argyll-robertson pupils. (adams et al., principles of neurology, 6th ed, pp722-8)

  • Tabes Dorsalis

    parenchymatous neurosyphilis marked by slowly progressive degeneration of the posterior columns, posterior roots, and ganglia of the spinal cord. the condition tends to present 15 to 20 years after the initial infection and is characterized by lightening-like pains in the lower extremities, urinary incontinence; ataxia; severely impaired position and vibratory sense, abnormal gait (see gait disorders, neurologic), optic atrophy; argyll-robertson pupils, hypotonia, hyperreflexia, and trophic joint degeneration (charcot's joint; see arthropathy, neurogenic). (from adams et al., principles of neurology, 6th ed, p726)

  • Neurosyphilis

    infection of the brain or spinal cord by treponema pallidum. it occurs many years following the original infection which remained untreated. signs and symptoms include abnormal gait, blindness, depression, paralysis, seizures and dementia.

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 A50.40 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 A50.40Overview

Is A50.40 (Late congenital neurosyphilis [juvenile neurosyphilis]) a billable code?

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

What is the ICD-9 equivalent of A50.40?

Under the General Equivalence Mappings, late congenital neurosyphilis, unspecified 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.