Question 1

What is ICD-10 code L42?

Accepted Answer

L42 is the ICD-10-CM diagnosis code for pityriasis rosea. A common, self-limited skin condition that typically presents with a distinctive rose-colored rash, often preceded by a single larger patch called a herald patch. L42 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).

L42 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.

Pityriasis rosea is usually benign and resolves spontaneously; document the presence of herald patch if noted.

Question 2

Is L42 an HCC code?

Accepted Answer

No. L42 is a billable ICD-10-CM code but does not map to any payment HCC category under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can still be reported on Medicare Advantage encounter data submissions, but it does not contribute to the beneficiary's Risk Adjustment Factor (RAF) score and therefore does not affect the risk-adjusted capitation payment to the plan. V28 reached 100% phase-in for payment year 2026.

Question 3

Is L42 billable?

Accepted Answer

Yes. L42 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. L42 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.

Question 4

What is the V28 vs V24 difference for L42?

Accepted Answer

L42 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 L42 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.

Question 5

What should coders know when reporting L42?

Accepted Answer

Pityriasis rosea is usually benign and resolves spontaneously; document the presence of herald patch if noted This condition is often confused with other rashes; ensure clinical documentation confirms the diagnosis

HCC Buddy Code Card

L42

Is L42 an HCC code?

What This Code Means

Coding Tips

Code Hierarchy

Open L42 in the Interactive Encoder

L42 ICD-10-CM Code: Pityriasis rosea

HCC Buddy Code Card

L42

Is L42 an HCC code?

What This Code Means

Coding Tips

Code Hierarchy

Open L42 in the Interactive Encoder