2026 ICD-10-CM Diagnosis Code H21.339Parasitic cyst of iris, ciliary body or anterior chamber, unspecified eye

ICD-10-CM Codes›H00–H59›H15-H22›H21

ICD-10-CM H21.339
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

H21.339 is a billable ICD-10-CM diagnosis code for parasitic cyst of iris, ciliary body or anterior chamber, unspecified eye. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 121 through 122. The code is flagged as an unspecified code, since codes identifying laterality exist in the same family. Coders also document this condition as cyst of anterior chamber of eye. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified eye disorders.

Code Identity

ICD-10-CM Code
H21.339
Billable Status
Yes — Valid for Submission
Code Describes
Parasitic cyst of iris, ciliary body or anterior chamber, unspecified eye
Short Description
Parastc cyst of iris, ciliary body or ant chamber, unsp eye
Parent Code
H21.33
Parasitic cyst of iris, ciliary body or anterior chamber

Code Classification

ChapterH00–H59Diseases of the eye and adnexa
SectionH15-H22Disorders of sclera, cornea, iris and ciliary body
CategoryH21Other disorders of iris and ciliary body
This CodeH21.339Parasitic cyst of iris, ciliary body or anterior chamber, unspecified eye

Code EditsBilling

Medicare Code Editor checks that affect claim validity for H21.339.

Unspecified codes
Unspecified codes exist in the ICD-10-CM classification for circumstances when documentation in the medical record does not provide the level of detail needed to support reporting a more specific code. However, in the inpatient setting, there should generally be very limited and rare circumstances for which the laterality (right, left, bilateral) of a condition is unable to be documented and reported. The following pages contain the list of unspecified ICD-10-CM diagnosis codes for which there is a more specific code to identify laterality (right, left, bilateral) within that code family.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Cyst of anterior chamber of eye
  • Infection of anterior chamber of eye caused by parasite
  • Parasitic cyst of anterior chamber
  • Parasitic cyst of ciliary body
  • Parasitic cyst of iris

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR EYE012
Other specified eye disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

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Convert H21.339 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
360.13 Parasitic endophthal NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About H21.339Overview

Is H21.339 (Parasitic cyst of iris, ciliary body or anterior chamber) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report parasitic cyst of iris, ciliary body or anterior chamber, unspecified eye on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does H21.339 group to?

When parasitic cyst of iris, ciliary body or anterior chamber, unspecified eye is the principal diagnosis on an inpatient stay, it groups to MS-DRG 121, 122, with relative weights from 0.7858 to 1.1633 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of H21.339?

Under the General Equivalence Mappings, parasitic cyst of iris, ciliary body or anterior chamber, unspecified eye converts to ICD-9-CM 360.13 (parasitic endophthal NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.