What is ICD-10 code L40.4?

L40.4 is the ICD-10-CM diagnosis code for Guttate psoriasis. A form of psoriasis that appears as small, drop-like lesions scattered across the body, often triggered by a streptococcal infection. It belongs to the ICD-10-CM chapter for diseases of the skin and subcutaneous tissue (l00-l99). L40.4 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. L40.4 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. L40.4 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. L40.4 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for L40.4?

L40.4 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards L40.4 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

What should coders know when reporting L40.4?

Document any preceding infection, particularly streptococcal pharyngitis, as this is a common trigger Note the distribution pattern and extent of lesions

L40.4 ICD-10 Code: Guttate psoriasis

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupL40.4Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the skin and subcutaneous tissue (L00-L99) / Papulosquamous disorders (L40-L45)

L40.4

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Guttate psoriasis

A form of psoriasis that appears as small, drop-like lesions scattered across the body, often triggered by a streptococcal infection.

Buddy Insight

Guttate psoriasis is characterized by acute onset of numerous small, drop-shaped scaly papules, often triggered by streptococcal pharyngitis in children and young adults.

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Not risk-adjusted for this model/period.

RAF 0

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Not risk-adjusted for this model/period.

RAF 0

RXHCC

Mapped

HCC 316

Psoriasis

RAF 0.0

Code Trumping

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Compare selected patient codes to show trumped or trumps impact.

Code Book Path

Official

L40Psoriasis

L40.4Guttate psoriasis

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for L40.4 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for L40.4 in this effective period.

Related Child Codes

Official

L40.0Psoriasis vulgaris

L40.1Generalized pustular psoriasis

L40.2Acrodermatitis continua

L40.3Pustulosis palmaris et plantaris

L40.5Arthropathic psoriasis

Includes

Official

ICD-10-CM does not list Includes notes for L40.4 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for L40.4 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for L40.4 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for L40.4 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for L40.4 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Provider documentation of guttate psoriasis

Description of characteristic small drop-like papules and distribution

Documentation of preceding streptococcal infection if applicable

Strep throat testing results or ASO titers if obtained

MEAT Support

HCC Buddy guidance

Provider documentation of guttate psoriasis

Description of characteristic small drop-like papules and distribution

Documentation of preceding streptococcal infection if applicable

Strep throat testing results or ASO titers if obtained

Audit Caution

HCC Buddy guidance

Coding as psoriasis vulgaris when the documentation specifically describes guttate morphology

Defaulting to unspecified psoriasis when guttate type is documented

Failing to code the triggering streptococcal infection when documented

Confusing with pityriasis rosea which has a similar age predilection and morphology

Common Mistakes

HCC Buddy guidance

L40.0 (Psoriasis vulgaris) — larger, well-defined plaques vs. small droplet-shaped lesions in guttate

L40.9 (Psoriasis, unspecified) — use L40.4 when guttate type is specifically documented

L42 (Pityriasis rosea) — can appear similar but follows a herald patch and has different distribution

L26 (Exfoliative dermatitis) — widespread scaling but different etiology and presentation

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 L40.4 an HCC code?

No. L40.4 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.

HCC Category Mapping

RxHCCHCC 316, Psoriasis

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

MEAT Criteria for L40.4

For L40.4to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed L40.4 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

L40.4 is the ICD-10-CM diagnosis code for guttate psoriasis. A form of psoriasis that appears as small, drop-like lesions scattered across the body, often triggered by a streptococcal infection. L40.4 sits in the ICD-10-CM chapter for diseases of the skin and subcutaneous tissue (l00-l99), within the section covering papulosquamous disorders (l40-l45).

L40.4 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.

Does not map to any CMS-HCC in V28, V24, or ESRD models. Maps only to RxHCC 316 (Psoriasis and Other Papulosquamous Disorders) for prescription drug risk adjustment. No direct Medicare Advantage RAF score impact. Coders reviewing L40.4 should check whether additional documentation would support a more specific child code in the same hierarchy that does map to a payment HCC, capturing the correct specificity is the highest-impact RAF improvement available within accurate coding.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for L40.4 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Document any preceding infection, particularly streptococcal pharyngitis, as this is a common trigger
•Note the distribution pattern and extent of lesions

Clinical Significance

Guttate psoriasis is characterized by acute onset of numerous small, drop-shaped scaly papules, often triggered by streptococcal pharyngitis in children and young adults. It is clinically significant because it may be the initial presentation of psoriasis and can evolve into chronic plaque psoriasis. Identification of the triggering infection is important for management.

Documentation Requirements

✓Provider documentation of guttate psoriasis
✓Description of characteristic small drop-like papules and distribution
✓Documentation of preceding streptococcal infection if applicable
✓Strep throat testing results or ASO titers if obtained
✓Treatment plan (topical therapy, phototherapy, antibiotics if indicated)
✓Assessment of disease course and likelihood of progression to chronic psoriasis

Commonly Confused Codes

•L40.0 (Psoriasis vulgaris) — larger, well-defined plaques vs. small droplet-shaped lesions in guttate
•L40.9 (Psoriasis, unspecified) — use L40.4 when guttate type is specifically documented
•L42 (Pityriasis rosea) — can appear similar but follows a herald patch and has different distribution
•L26 (Exfoliative dermatitis) — widespread scaling but different etiology and presentation