Clinical Appearance of Lichen Planus Chronicus
Lichen planus chronicus presents as violaceous (dark red/purple), polygonal, flat-topped papules and plaques, often covered with fine white lines called Wickham striae, typically affecting flexor surfaces of the wrists, forearms, and legs with significant pruritus. 1, 2
Classic Cutaneous Features
The characteristic appearance follows the traditional "six P's" description 1, 3:
- Planar (flat-topped) papules and plaques 1
- Purple to violaceous coloration 1, 4
- Polygonal shape 1, 4
- Pruritic (often severely itchy) 1, 4
- Papules and plaques as primary lesions 1
Wickham striae - fine, lacy, reticular white lines - commonly overlay the lesions and are a key diagnostic feature 1. These white intersecting lines help distinguish lichen planus from other papulosquamous conditions 2.
Distribution Patterns
The lesions typically appear on 1, 4:
- Flexor surfaces of wrists and forearms 1
- Ankles and lower legs 1, 5
- Lower back 5
- Trunk and extremities in generalized cases 2, 6
The onset is usually acute, with lesions developing over weeks to months 1.
Mucosal Involvement
Oral and genital mucosa may show erosions and white striae, which can be debilitating and more persistent than cutaneous disease 1, 4. Oral lichen planus may predispose to squamous cell carcinoma development within lesions 4.
Important Distinguishing Features from Lichen Sclerosus
Critical pitfall to avoid: Do not confuse lichen planus with lichen sclerosus, which presents with porcelain-white papules and plaques (not violaceous) often with areas of ecchymosis 2, 7. Lichen sclerosus affects anogenital areas predominantly and spares vaginal mucosa, whereas lichen planus can involve true mucosal surfaces 2.
Atypical Presentations
In children, the presentation may be more heterogeneous and atypical 6, 5:
- Exanthematous (eruptive) form with rapid development of multiple white-grayish papules and plaques 6
- Vesiculobullous subtype presenting with blisters that may mimic cellulitis 3
Chronic Features
- Lesions may become more hyperkeratotic and plaque-like 3
- Pruritus remains severe and often worse at night 1
- Scalp involvement can lead to scarring alopecia 1, 4
- Nail involvement may occur with dystrophy 1, 4
The disease may resolve spontaneously within one to two years, though recurrences are common, and mucosal disease tends to be more persistent 1.