H21.331 ICD-10-CM Code: Parasitic cyst of iris, ciliary body or anterior chamber, right eye
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FY 2026 Apr update / Diseases of the eye and adnexa (H00-H59) / Disorders of sclera, cornea, iris and ciliary body (H15-H22)
H21.331
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceParasitic cyst of iris, ciliary body or anterior chamber, right eye
A fluid-filled sac caused by a parasite in the iris, ciliary body, or front chamber of the right eye.
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 H21.331 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for H21.331 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for H21.331 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for H21.331 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for H21.331 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for H21.331 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for H21.331 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 H21.331 an HCC code?
No. H21.331 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
H21.331 is the ICD-10-CM diagnosis code for parasitic cyst of iris, ciliary body or anterior chamber, right eye. A fluid-filled sac caused by a parasite in the iris, ciliary body, or front chamber of the right eye. H21.331 sits in the ICD-10-CM chapter for diseases of the eye and adnexa (h00-h59), within the section covering disorders of sclera, cornea, iris and ciliary body (h15-h22).
H21.331 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 documentation specifies parasitic origin to distinguish from non-parasitic cysts.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for H21.331 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify documentation specifies parasitic origin to distinguish from non-parasitic cysts
- •Confirm laterality is documented as right eye; use H21.339 if eye not specified