A42.89 ICD-10-CM Code: Other forms of actinomycosis
HCC Buddy Code Card
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FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Other bacterial diseases (A30-A49)
A42.89
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOther forms of actinomycosis
Actinomycosis is a rare bacterial infection caused by Actinomyces organisms that can affect various parts of the body. This code represents forms of actinomycosis that don't fit into the more common categories like lung, abdominal, or cervicofacial infections.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for A42.89 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for A42.89 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for A42.89 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for A42.89 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for A42.89 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for A42.89 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for A42.89 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 A42.89 an HCC code?
No. A42.89 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
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
A42.89 is the ICD-10-CM diagnosis code for other forms of actinomycosis. Actinomycosis is a rare bacterial infection caused by Actinomyces organisms that can affect various parts of the body. This code represents forms of actinomycosis that don't fit into the more common categories like lung, abdominal, or cervicofacial infections. A42.89 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering other bacterial diseases (a30-a49).
A42.89 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.
Verify the specific site of infection in the clinical documentation, as other actinomycosis codes (A42.0-A42.7) may be more specific and should be used if the infection location is clearly documented.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for A42.89 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify the specific site of infection in the clinical documentation, as other actinomycosis codes (A42.0-A42.7) may be more specific and should be used if the infection location is clearly documented
- •This code should only be used when the actinomycosis presentation is atypical or involves multiple sites that don't fit standard classifications; ensure documentation supports the 'other forms' designation