2027 ICD-10-CM Diagnosis Code A50.40Late congenital neurosyphilis, unspecified
ICD-10-CM Codes›A00–B99›A50-A64›A50
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Chronic Condition
A50.40 is a billable ICD-10-CM diagnosis code for late congenital neurosyphilis, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 97 through 99. 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 96 closely related codes. 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
Code Classification
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
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to A50.40: its own notes plus those printed at A50.4, 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.
- 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.
- Juvenile neurosyphilis NOS
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- Hutchinson's triad (A50.53)
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.
- human immunodeficiency virus [HIV] disease (B20)
- 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.
- code to identify any associated mental disorder
- 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 A50.40, its category, or a range that includes it.
Applicable To 1
These notes mention A50.40.
- O98.1 Syphilis complicating pregnancy, childbirth and the puerperium
Excludes2 3
These codes carry an Excludes2 note naming A50.40: its condition is not part of those codes, and both may be reported when the patient has both.
- Block P35-P39 Infections specific to the perinatal periodcongenital syphilis (A50.-) names A50.-, which includes this code
- P37 Other congenital infectious and parasitic diseasescongenital syphilis (A50.-) names A50.-, which includes this code
- Block A65-A69 Other spirochetal diseases
Code First 2
These codes say to code first a condition named in the note, and A50.40 is one of the conditions named.
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.
Clinical InformationClinical
Syphilis, Congenital
syphilis acquired in utero and manifested by any of several characteristic tooth (hutchinson's teeth) or bone malformations and by active mucocutaneous syphilis at birth or shortly thereafter. ocular and neurologic changes may also occur.
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.
Code HistoryHistory
Questions About A50.40Overview
What is the ICD-10 code for late congenital neurosyphilis, unspecified?
The ICD-10-CM code for late congenital neurosyphilis, unspecified is A50.40 (sometimes written as A5040). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
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, 2026 through September 30, 2027.
What MS-DRG does A50.40 group to?
When late congenital neurosyphilis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 98, 99, 97, with relative weights from 1.5249 to 3.8208 depending on complications. Higher weights mean higher Medicare reimbursement.
Is A50.40 a CC or MCC?
CMS lists A50.40 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 96 closely related codes in its exclusion list.
Can A50.40 be reported with A50.53?
Not as a rule. The Excludes1 note at A50.4, which applies to A50.40, lists "Hutchinson's triad (A50.53)". 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).
