2026 ICD-10-CM Diagnosis Code L56.4Polymorphous light eruption

ICD-10-CM Codes›L00–L99›L55-L59›L56

ICD-10-CM L56.4
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

L56.4 is a billable ICD-10-CM diagnosis code for polymorphous light eruption. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 606 through 607. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Allergic reactions and Other specified and unspecified skin disorders.

Code Identity

ICD-10-CM Code
L56.4
Billable Status
Yes — Valid for Submission
Code Describes
Polymorphous light eruption
Short Description
Polymorphous light eruption
Same as the full description in the CMS dataset.
Parent Code
L56
Other acute skin changes due to ultraviolet radiation

Code Classification

ChapterL00–L99Diseases of the skin and subcutaneous tissue
SectionL55-L59Radiation-related disorders of the skin and subcutaneous tissue
CategoryL56Other acute skin changes due to ultraviolet radiation
This CodeL56.4Polymorphous light eruption

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acne estivalis
  • Acne exacerbated by light
  • Diffuse dermatitis
  • Diffuse inflammatory erythema
  • Hydroa vacciniforme
  • Juvenile spring eruption
  • Photoaggravation of disorder
  • Polymorphous light eruption
  • Polymorphous light eruption, diffuse erythematous type
  • Polymorphous light eruption, eczematous type
  • Polymorphous light eruption, papular type
  • Polymorphous light eruption, papulovesicular type
  • Polymorphous light eruption, plaque type

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Eruption
      • Hutchinson, summer
    • Eruption
      • polymorphous light (sun)
    • Hutchinson's
      • disease, meaning
        • prurigo estivalis
    • Hutchinson's
      • disease, meaning
        • summer eruption or summer prurigo
    • Hydroa
      • aestivale
    • Hydroa
      • vacciniforme
    • Prurigo(ferox) (gravis) (Hebrae) (Hebra's) (mitis) (simplex)
      • estivalis

Clinical ClassificationClinical

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

CCSR INJ031
Allergic reactions
Default principal diagnosis: inpatient No · outpatient No
CCSR SKN007
Other specified and unspecified skin disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Hydroa Vacciniforme

    a vesicular and bullous eruption having a tendency to recur in summer during childhood and commonly appearing on sun-exposed skin. the lesions are surrounded by an erythematous zone and resemble a vaccination. (from dorland, 27th ed)

  • Polymorphous Light Eruption

    a red, edematous rash that occurs on areas of the skin with recent exposure to sunlight.

  • Classic Hydroa Vacciniforme Lymphoproliferative Disorder|Classic HV LPD|Classic HV-LPD

    hydroa vacciniforme lymphoproliferative disorder characterized by the presence of self-limited papulovesicular skin lesions in sun-exposed areas. there is no involvement of internal organs. it has an indolent course and usually affects white individuals.

  • Hydroa Vacciniforme

    a rare skin disorder of unknown etiology affecting children. it is a photodermatitis, characterized by the formation of vesicles and scarring on sun exposed areas.

  • Hydroa Vacciniforme Lymphoproliferative Disorder|HV LPD|HV-LPD|HV-Like LPD|HV-Like Lymphoma|Hydroa Vacciniforme-Like Cutaneous T-Cell Lymphoma|Hydroa Vacciniforme-Like Lymphoma|Hydroa Vacciniforme-Like Lymphoma|Hydroa Vacciniforme-Like Lymphoproliferative Disorder|Hydroa vacciniforme-like lymphoma

    a rare, ebv-positive cutaneous t-cell lymphoproliferative disorder, composed of cd8 positive cytotoxic t-lymphocytes. it affects children, almost exclusively in latin america and asia. patients present with papulovesicular skin lesions, clinically resembling hydroa vacciniforme, in areas of sun-exposed skin.

  • Systemic Hydroa Vacciniforme Lymphoproliferative Disorder|Systemic HV LPD|Systemic HV-LPD

    hydroa vacciniforme lymphoproliferative disorder characterized by severe clinical course and associated with fever, lymph node involvement, and involvement of internal organs by ebv-positive t-cells and nk-cells. it usually affects asian and latin american individuals.

Patient EducationClinical

Rashes

A rash is an area of irritated or swollen skin. Many rashes are itchy, red, painful, and irritated. Some rashes can also lead to blisters or patches of raw skin. Rashes are a symptom of many different medical problems. Other causes include irritating substances and allergies. Certain genes can make people more likely to get rashes.

Read the full article at MedlinePlus

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

Convert L56.4 to ICD-9-CMHistory

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

ICD-9-CM
692.82 Dermatitis oth radiation
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 L56.4Overview

Is L56.4 (Other acute skin changes due to ultraviolet radiation) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report polymorphous light eruption on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does L56.4 group to?

When polymorphous light eruption is the principal diagnosis on an inpatient stay, it groups to MS-DRG 606, 607, with relative weights from 0.9064 to 1.5132 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of L56.4?

Under the General Equivalence Mappings, polymorphous light eruption converts to ICD-9-CM 692.82 (dermatitis oth radiation). 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.