ICD-10 Code L66.4 – Folliculitis ulerythematosa reticulata (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L66.4 – Folliculitis ulerythematosa reticulata
What it is
This code identifies folliculitis ulerythematosa reticulata, a rare scarring hair disorder. Use it when documentation names this specific condition affecting hair follicles and causing permanent loss.
Clinical signs
Clinical features vary; refer to documentation. Standard references describe follicular inflammation with scarring and patchy hair loss, often with a reticulated or net-like pattern.
When to use this code
Use L66.4 when the provider documents folliculitis ulerythematosa reticulata by name. It may also apply when the record clearly links the diagnosis to cicatricial alopecia with this specific pattern. If the note only says nonspecific folliculitis or hair loss, check documentation before coding.
Do not use for
Do not use this code for simple infectious folliculitis, alopecia without scarring, or other specified cicatricial alopecias. If the diagnosis is unclear, check documentation.
Coding tip
Code this only when the chart explicitly supports the named disorder, not when hair loss or folliculitis is described generally.