2027 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 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 121 through 122. 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 29 closely related codes. 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
  • Secondary iris cyst

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to H21.339: its own notes plus those printed at H21.3, H21, and Chapter 7. A note printed at a category, block or chapter applies to every code under it.

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.

From H21.3 Cyst of iris, ciliary body and anterior chamber applies to 24 codes
From H21 Other disorders of iris and ciliary body applies to 97 codes
From Chapter 7 (H00-H59) Diseases of the eye and adnexa applies to 2,677 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • diabetes mellitus related eye conditions (E09.3-, E10.3-, E11.3-, E13.3-)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury (trauma) of eye and orbit (S05.-)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
  • syphilis related eye disorders (A50.01, A50.3-, A51.43, A52.71)

Notes

General instructions on how these codes are used.

From Chapter 7 (H00-H59) Diseases of the eye and adnexa applies to 2,677 codes
  • Use an external cause code following the code for the eye condition, if applicable, to identify the cause of the eye condition

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

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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Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

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, 2026 through September 30, 2027.

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 122, 121, with relative weights from 0.7403 to 1.2249 depending on complications. Higher weights mean higher Medicare reimbursement.

Is H21.339 a CC or MCC?

CMS lists H21.339 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 29 closely related codes in its exclusion list.

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.