Line Field Confocal Optical Coherence Tomography (LC-OCT) Features of Primary Cicatricial Alopecias

Primary cicatricial alopecias (PCA) are rare inflammatory disorders that irreversibly destroy hair follicles, making early, accurate diagnosis crucial.

The aim of this study is to describe line field confocal optical coherence tomography (LC-OCT) features of major PCA subtypes and assess its potential role in diagnosis and disease monitoring.

Twenty-five patients with PCA (lichen planopilaris [LPP], frontal fibrosing alopecia [FFA], folliculitis decalvans [FD], discoid lupus erythematosus [DLE], dissecting cellulitis of the scalp [DCS]) underwent LC-OCT imaging with vertical, horizontal, and 3D acquisitions of clinically and trichoscopically selected lesions. Images were independently evaluated to identify both shared and subtype-specific patterns.

In active lesions of LPP/FFA (n = 15), infundibular hyperkeratosis with hyper-reflective keratinous sleeves was observed in 14/15 (93.3%), perifollicular bright inflammatory aggregates in 7/15 (46.6%), and dilated dermal vessels in 9/15 (60.0%). DLE (n = 4) was characterized by periadnexal inflammation, basal vacuolar alteration, and a continuous hyper-reflective junctional band in 4/4 (100%), dermal hyporeflective bands compatible with mucin in 2/4 (50.0%), and follicular plugs in 2/4 (50.0%). FD (n = 4) demonstrated tufted follicles with markedly dilated infundibula in 3/4 (75.0%), pustule-like hyporeflective cavities in 2/4 (50.0%), and periadnexal inflammatory infiltrates in 3/4 (75.0%). DCS (n = 2) showed superficial abscess-like lobulated hyporeflective cavities with perifollicular inflammatory clusters in 2/2 (100%) and follicular fusion with hair tufting in 1/2 (50.0%). In end-stage cicatricial areas, LC-OCT demonstrated follicular dropout with loss of sebaceous glands, dermal sclerosis forming a stellate pattern, and a flattened, hyper-reflective dermal-epidermal junction in all 25/25 cases (100%).

LC-OCT identifies shared scarring signatures as well as distinct patterns among PCA subtypes, and it supports targeted biopsy site selection. Moreover, it provides a noninvasive tool for real-time assessment of disease activity that is complementary to trichoscopy and histopathology.