A50.56 ICD-10-CM Code: Late congenital syphilitic osteochondropathy
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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 guidanceLate 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
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
00
RAF 0
Code Trumping
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Code Book Path
Inclusion Terms
Official- Any congenital syphilitic condition specified as late or manifest two years or more after birth.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for A50.56 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for A50.56 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for A50.56 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for A50.56 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for A50.56 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for A50.56 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is A50.56 an HCC code?
No. A50.56 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
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 does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
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, RAF weights, 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