Wickham Striae — SCE Dermatology MCQ
Instant feedback + full explanation. One question, done properly.
Educational content. Not a substitute for clinical judgement or local policy.
Reveal the answer and explanation
Correct answer: C — Compact orthokeratosis overlying wedge-shaped hypergranulosis — the thickened granular layer produces the white appearance
The correct answer is C, compact orthokeratosis overlying wedge-shaped hypergranulosis, with the thickened granular layer producing the white appearance. Wickham striae are the clinical and dermoscopic counterpart of this histological finding: light is reflected off the thickened, compact stratum corneum and the underlying wedge of granular layer, producing the characteristic white lacy lines seen on lichen planus papules. This wedge-shaped hypergranulosis, together with a sawtooth pattern of the rete ridges and a band-like lymphocytic infiltrate at the dermo-epidermal junction, is one of the classic histological hallmarks of lichen planus. Recognising this link allows the clinician to correlate the dermoscopic reticular white pattern directly with the underlying pathology rather than relying on morphology alone. Why the other options are wrong: E. Acantholysis: this is loss of keratinocyte cohesion seen in pemphigus and Darier disease, not a feature of lichen planus, and does not explain a white surface pattern. B. Keratin plugging: this refers to follicular plugging typical of discoid lupus erythematosus and keratosis pilaris, producing follicular scale rather than the reticular surface lines of Wickham striae. A. Parakeratosis: retained nuclei in the stratum corneum are typical of psoriasis and are not a feature of lichen planus, which characteristically shows orthokeratosis (no retained nuclei). D. Spongiosis: intercellular epidermal oedema is the hallmark of eczematous dermatitis, not the interface, lichenoid pattern of lichen planus. Key point: Wickham striae are white because light reflects off compact orthokeratosis sitting above a wedge of hypergranulosis, the classic histological signature of lichen planus.
Reference: Primary Care Dermatology Society (PCDS), Lichen Planus guidance; histology corroborated by Karadag et al., Roxburgh's Common Skin Diseases (2022): compact orthokeratosis above zones of wedge-shaped hypergranulosis and acanthosis corresponds to Wickham striae. https://www.pcds.org.uk/clinical-guidance/lichen-planus