ICD-10 Code L99 – Other disorders of skin and subcutaneous tissue in diseases classified elsewhere (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L99 – Other disorders of skin and subcutaneous tissue in diseases classified elsewhere
What it is
L99 is a diagnosis code for skin or subcutaneous tissue disorders that are caused by another underlying disease. Use it when the skin problem is secondary and the record links it to a separate condition.
Clinical signs
Clinical features vary; refer to documentation. You may see skin changes, nodules, plaques, or other tissue abnormalities described as part of a systemic disease rather than a primary skin disorder.
When to use this code
Use L99 when the provider documents a skin or subcutaneous tissue disorder due to another disease and no more specific code is available. The chart should identify the underlying condition and the secondary skin finding. If the cause is unclear, check documentation before assigning this code.
Do not use for
Do not use L99 for a primary skin disease, or when a more specific ICD-10-CM code describes the condition. Do not assign it if the record does not support a secondary relationship.
Coding tip
Always code the underlying disease first when documentation shows the skin disorder is secondary.