ICD-10 Code L91.9 – Hypertrophic disorder of the skin, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L91.9 – Hypertrophic disorder of the skin, unspecified
What it is
L91.9 identifies a nonspecific thickening or overgrowth of the skin when the exact type of hypertrophic disorder is not documented. Use it when the record confirms a skin overgrowth but does not name a more specific diagnosis.
Clinical signs
Findings may include localized thickened, raised, or firm skin. Clinical features vary; refer to documentation for the exact lesion description and whether it is hypertrophic rather than another skin condition.
When to use this code
Use L91.9 when the clinician documents hypertrophic skin disorder, skin thickening, or similar wording without further specification. It is appropriate when the note supports a benign overgrowth of skin and no more precise subtype is recorded. Check documentation if the lesion could be a scar, keloid, or other defined condition.
Do not use for
Do not use this code when the chart identifies a specific disorder such as a keloid or hypertrophic scar. Also avoid it if the documentation describes a different skin lesion or the diagnosis is not confirmed.
Coding tip
If the provider names only “thickened skin,” query for the exact diagnosis before defaulting to L91.9.