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

L56.4 is a billable ICD-10-CM diagnosis code for polymorphous light eruption. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) 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
  • Vesicular eruption

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to L56.4: its own notes plus those printed at L56 and Chapter 12. 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 Chapter 12 (L00-L99) Diseases of the skin and subcutaneous tissue applies to 1,001 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)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • lipomelanotic reticulosis (I89.8)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
  • systemic connective tissue disorders (M30-M36)
  • viral warts (B07.-)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From L56 Other acute skin changes due to ultraviolet radiation applies to 8 codes
  • code to identify the source of the ultraviolet radiation (W89, X32)

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

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name L56.4, its category, or a range that includes it.

Excludes1 3

These codes carry an Excludes1 note naming L56.4: they are not reported together with it, unless the two conditions are unrelated.

  • K13.0 Diseases of lips
    cheilitis due to radiation-related disorders (L55-L59) names L55-L59, which includes this code
  • T66 Radiation sickness, unspecified
    radiation related disorders of the skin and subcutaneous tissue (L55-L59) names L55-L59, which includes this code
  • T67 Effects of heat and light
    radiation-related disorders of the skin and subcutaneous tissue (L55-L59) names L55-L59, which includes this code

Excludes2 6

These codes carry an Excludes2 note naming L56.4: its condition is not part of those codes, and both may be reported when the patient has both.

  • Block L20-L30 Dermatitis and eczema
    radiation-related disorders of the skin and subcutaneous tissue (L55-L59) names L55-L59, which includes this code
  • L23 Allergic contact dermatitis
    radiation-related disorders of the skin and subcutaneous tissue (L55-L59) names L55-L59, which includes this code
  • L24 Irritant contact dermatitis
    radiation-related disorders of the skin and subcutaneous tissue (L55-L59) names L55-L59, which includes this code
  • L25 Unspecified contact dermatitis
    radiation-related disorders of the skin and subcutaneous tissue (L55-L59) names L55-L59, which includes this code
  • Block T20-T32
    radiation-related disorders of the skin and subcutaneous tissue (L55-L59) names L55-L59, which includes this code
  • X32 Exposure to sunlight
    radiation-related disorders of the skin and subcutaneous tissue (L55-L59) names L55-L59, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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

  • Polymorphous Light Eruption

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

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

Questions About L56.4Overview

What is the ICD-10 code for polymorphous light eruption?

The ICD-10-CM code for polymorphous light eruption is L56.4 (sometimes written as L564). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

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, 2026 through September 30, 2027.

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 607, 606, with relative weights from 0.8772 to 1.5721 depending on complications. Higher weights mean higher Medicare reimbursement.

Does L56.4 need an additional code?

When the condition applies, yes. The Use Additional Code note at L56, which applies to L56.4, reads: code to identify the source of the ultraviolet radiation (W89, X32). The additional code is reported after L56.4.

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.