What is ICD-10 code A50.56?

A50.56 is the ICD-10-CM diagnosis code for Late congenital syphilitic osteochondropathy. It belongs to the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99). A50.56 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. A50.56 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. A50.56 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. A50.56 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does A50.56 map to under V28?

A50.56 has no payable CMS-HCC V28 mapping in the final FY2026 CMS file.

What RAF reference is published for A50.56?

A50.56 has no V28 reference coefficient because the final FY2026 source verifies no payable V28 mapping.

What is the V28 vs V24 difference for A50.56?

A50.56 has verified no payable V28 mapping in the final FY2026 source. Select a historical effective period before making any V24 comparison.

2026 ICD-10-CM A50.56: Late congenital syphilitic

A50.56 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC coding software

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Code lookupA50.56Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Infections with a predominantly sexual mode of transmission (A50-A64)

A50.56

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Late congenital syphilitic osteochondropathy

This is a bone and cartilage disease that develops in children born with syphilis, occurring years after birth as a late manifestation of the infection passed from mother to child. It causes damage to the bones and joints, particularly affecting the long bones of the legs.

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

N/A

—

Not risk-adjusted for this model/period.

Not mapped

ESRD/PACE

N/A

—

Not risk-adjusted for this model/period.

Not mapped

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

A50Congenital syphilis

A50.5Other late congenital syphilis, symptomatic

A50.56Late congenital syphilitic osteochondropathy

Inclusion Terms

Official

Any congenital syphilitic condition specified as late or manifest two years or more after birth.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for A50.56 in this effective period.

Related Child Codes

Official

A50.51Clutton's joints

A50.52Hutchinson's teeth

A50.53Hutchinson's triad

A50.54Late congenital cardiovascular syphilis

A50.55Late congenital syphilitic arthropathy

Includes

Official

ICD-10-CM does not list Includes notes for A50.56 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for A50.56 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for A50.56 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for A50.56 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for A50.56 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

This code requires documentation confirming late congenital syphilis with skeletal involvement; verify the patient's age and maternal syphilis history in the medical record

Do not use this code for early congenital syphilis or acquired syphilis; ensure the osteochondropathy is specifically documented as a late manifestation of congenital syphilis

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is A50.56 an HCC code?

No. A50.56 is a billable ICD-10-CM code with no mapping under the CMS-HCC V28 or V24 community payment models, and none under the ESRD, Part D RxHCC, or HHS-HCC models.

Code: A50.56
Description: Late congenital syphilitic osteochondropathy
HCC (V28): No CMS-HCC V28 mapping
RAF reference coefficient: —
Billable: Yes
Payment year: 2026

Coder workflow notes

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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).

What This Code Means

A50.56 is the ICD-10-CM diagnosis code for late congenital syphilitic osteochondropathy. This is a bone and cartilage disease that develops in children born with syphilis, occurring years after birth as a late manifestation of the infection passed from mother to child. It causes damage to the bones and joints, particularly affecting the long bones of the legs. A50.56 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering infections with a predominantly sexual mode of transmission (a50-a64).

A50.56 is a billable ICD-10-CM code, but the current payload does not show a mapping under the CMS-HCC V28 or V24 community payment models, and none under the ESRD, Part D RxHCC, or HHS-HCC models. Do not assign risk adjustment value from this page when no source-backed mapping is shown; verify the applicable model and payment year.

This code requires documentation confirming late congenital syphilis with skeletal involvement; verify the patient's age and maternal syphilis history in the medical record.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for A50.56 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This code requires documentation confirming late congenital syphilis with skeletal involvement; verify the patient's age and maternal syphilis history in the medical record
•Do not use this code for early congenital syphilis or acquired syphilis; ensure the osteochondropathy is specifically documented as a late manifestation of congenital syphilis