ICD-10 Code L66 – Cicatricial alopecia [scarring hair loss] (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L66 – Cicatricial alopecia [scarring hair loss]
What it is
L66 identifies cicatricial alopecia, a group of disorders that destroy hair follicles and replace them with scar tissue. Hair loss in the affected area is usually permanent.
Clinical signs
Typical findings include patchy hair loss with loss of follicular openings, scalp inflammation, scaling, redness, or shiny scarred skin. Clinical features vary; refer to documentation.
When to use this code
Use L66 when the provider documents scarring alopecia, cicatricial alopecia, or a specific scarring hair-loss disorder in the L66 category. It fits cases where the record confirms permanent follicle damage rather than temporary shedding. Check documentation if the note only says “alopecia” without scarring.
Do not use for
Do not use L66 for non-scarring hair loss such as androgenetic alopecia, telogen effluvium, or alopecia areata unless scarring is documented. Also avoid it when the diagnosis is uncertain or not stated.
Coding tip
Code the documented scarring type or underlying cause when the record supports it, and do not assume cicatricial alopecia from hair loss alone.