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Annular Atrophic Lichen Planus

Author: Dr Kiah Lunstone 

Chief Editor: Dr Daniel Keith

Lichen planus (LP) is a chronic immune mediated disorder which affects the skin and mucus membranes. Classic Lichen planus presents with the four P’s: purple pruritic polygonal papules. However, there are a myriad of other morphologic variants which differ in their presentation. This page will cover the most rare variant: Annular Atrophic Lichen Planus (AALP). 

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AALP is a rare variant of lichen planus which has both features of annular and atrophic lichen planus. Is is distinct clinical entity and histopathological examination shows a characteristic reduction of elastin fibres in the superficial dermis. AALP has a chronic course and is difficult to treat. Unlike other subtypes of lichen Planus, AALP is often resistant to treatment with topical or systemic corticosteroids.

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Macroscopic Appearance 

Typical features:

  • Violaceous / hyperpigmented papules which expand centrifugally to form atrophic plaques withraised borders

  • Typically affect the trunk and extremities

  • May be pruritic

AALP Figure 1.png

Dermoscopic Appearance 

Overview

 

Different variants of lichen planus have distinct features which can be identified on Dermoscopy toaid in diagnosis. However, there is of course overlap between the different subtypes.

 

These features can be broadly classified into:

  • Morphology of Wickham striae (WS)

  • Patterns of pigmentation

  • Vascular appearance

 

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Here are the key Dermoscopic features seen In annular atrophic lichen planus:

Wickham Striae

 

  • These are the hallmark of lichen planus

  • In AALP Wickham Striae are typically annular (circular)

  • Note that Wickham striae may be absent in some AALP lesions. Wickham striae are seen in activelesions but usually disappear with treatment.

AALP Figure 2.png

Pattern of Pigmentation and Vascular appearance

  • A number of different pigmentation patterns have been identified on Dermoscopy in AALP.

  • These can look quite different depending on Fitzpatrick skin type

  • The key ones include:

    • Peppering – The accumulation of multiple very small, blue-grey dots

    • Perifollicular pigmentation – giving the pigmentation a reticular appearance

AALP Figure 3.png
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