2027 ICD-10-CM Diagnosis Code A51.46Secondary syphilitic osteopathy
ICD-10-CM Codes›A00–B99›A50-A64›A51
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Chronic Condition
A51.46 is a billable ICD-10-CM diagnosis code for secondary syphilitic osteopathy. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 539 through 541. 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 453 closely related codes. Coders also document this condition as secondary syphilis of bone. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified bone disease and musculoskeletal deformities and Sexually transmitted infections (excluding HIV and hepatitis).
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Secondary syphilis of bone
- Secondary syphilis of musculoskeletal system
- Secondary syphilitic periostitis
- Syphilis of bone
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to A51.46: its own notes plus those printed at 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
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
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 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 A51.46, its category, or a range that includes it.
Applicable To 1
These notes mention A51.46.
- O98.1 Syphilis complicating pregnancy, childbirth and the puerperium
Excludes1 1
These codes carry an Excludes1 note naming A51.46: they are not reported together with it, unless the two conditions are unrelated.
- M90 Osteopathies in diseases classified elsewheresecondary syphilis (A51.46)
Excludes2 1
These codes carry an Excludes2 note naming A51.46: its condition is not part of those codes, and both may be reported when the patient has both.
- Block A65-A69 Other spirochetal diseases
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Periostitis (albuminosa) (circumscribed) (diffuse) (infective) (monomelic) See Also: Osteomyelitis;
secondary A51.46
Syphilis, syphilitic (acquired) A53.9
secondary A51.46
early (secondary) A51.46
secondary (and primary) A51.49
bone A51.46
periosteum, periostitis A51.46
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Bone Infections
Like other parts of the body, bones can get infected. The infections are usually bacterial, but can also be fungal. They may spread to the bone from nearby skin or muscles, or from another part of the body through the bloodstream.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert A51.46 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About A51.46Overview
What is the ICD-10 code for secondary syphilitic osteopathy?
The ICD-10-CM code for secondary syphilitic osteopathy is A51.46 (sometimes written as A5146). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is A51.46 (Other secondary syphilis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report secondary syphilitic osteopathy on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does A51.46 group to?
When secondary syphilitic osteopathy is the principal diagnosis on an inpatient stay, it groups to MS-DRG 541, 539, 540, with relative weights from 0.8293 to 1.9376 depending on complications. Higher weights mean higher Medicare reimbursement.
Is A51.46 a CC or MCC?
CMS lists A51.46 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 453 closely related codes in its exclusion list.
Can A51.46 be reported with N34.1?
Not as a rule. The Excludes1 note at block A50-A64, which applies to A51.46, lists "nonspecific and nongonococcal urethritis (N34.1)". 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).
