L40: ICD10 Code for Psoriasis

L40 refers to Psoriasis, a group of immune-mediated or idiopathic skin disorders marked by scaly, red, and inflamed patches. These conditions vary in severity, chronicity, and treatment response, often requiring dermatologic expertise for diagnosis and management.

Symptoms

• Scaly red plaques – Common in psoriasis (L40) and parapsoriasis (L41)
• Itchy oval patches – Classic sign of pityriasis rosea (L42)
• Flat-topped purple papules – Seen in lichen planus (L43)
• Mucosal involvement – Can occur in lichen planus and certain L44 disorders
• Skin thickening and flaking – Common across most papulosquamous diseases

Diagnosis

Diagnosis of Psoriasis involves clinical examination, skin biopsy, dermoscopy, and sometimes patch or blood testing to rule out autoimmune or drug-related causes. Chronicity and pattern of lesions help differentiate among the types.

ICD10 Code Usage

ICD10 code L40 is used by dermatologists, internists, and immunologists to document autoimmune or inflammatory skin conditions. It supports insurance billing, therapy selection (e.g., biologics, steroids), and long-term disease monitoring.

Related Codes

• L41 – Parapsoriasis
• L42 – Pityriasis rosea
• L43 – Lichen planus
• L44 – Other papulosquamous disorders
• L45 – Papulosquamous disorders in diseases classified elsewhere

FAQs

Q1: What is ICD10 code L40?
A: It refers to Psoriasis, a skin disorder marked by red, scaly, or inflamed plaques or patches due to immune dysfunction or unknown causes.

Q2: Is psoriasis (L40) the same as parapsoriasis (L41)?
A: No—psoriasis is more well-defined and chronic, while parapsoriasis includes a group of disorders that may mimic psoriasis but behave differently.

Q3: What is pityriasis rosea (L42)?
A: A self-limited rash that often begins with a “herald patch” followed by smaller scaly eruptions, likely triggered by viral infections.

Q4: Can these conditions affect internal organs?
A: Most are skin-limited, though lichen planus can occasionally affect the mucous membranes or nails.

Q5: Who manages these conditions?
A: Dermatologists typically lead treatment with support from immunologists or rheumatologists if systemic symptoms occur.

Conclusion

ICD10 code L40 enables accurate documentation and care planning for Psoriasis, supporting effective treatment of chronic inflammatory and immune-mediated skin disorders.