32: Lichen Planus Flashcards
What are the classic features of Lichen Planus?
The classic features of Lichen Planus, known as the 4P’s, are: 1. Purple 2. Polygonal 3. Pruritic 4. Papules
What is the role of CD8 T cells in the pathogenesis of Lichen Planus?
CD8 T cells serve as the effector cells in Lichen Planus, involved in initial antigen recognition, release of cytokines, and inducing apoptosis in keratinocytes.
What factors are suggested to potentially trigger Lichen Planus?
Potential triggers for Lichen Planus include contact sensitizers (e.g., metals), drugs (biologics, TNF-α inhibitors), and alloantigens in lichenoid GVHD.
What is the significance of lymphocyte activation in Lichen Planus?
Lymphocyte activation involves CD8 T cells releasing cytokines, induces expression of inflammatory chemokines, and affects the balance between activation and downregulation.
What are the possible mechanisms of keratinocyte apoptosis in Lichen Planus?
Possible mechanisms include Granzyme B activation of caspase-3 and TNF-α interaction with its receptor leading to matrix component expression.
What role do T regulatory cells play in oral lichen planus?
T regulatory cells correlate with disease subtype and activity, disrupting dendritic cell and allogeneic T-cell interactions.
What is the prevalence of oral lichen planus and its demographic characteristics?
The prevalence varies from 0.1% to 4%, most common in individuals aged 30-60 years, with no clear sexual or racial predilection.
What are the clinical features of cutaneous lichen planus?
Cutaneous lichen planus is characterized by well-marginated dull red-violet papules, Wickham striae, symmetrical distribution, and extreme pruritus.
What is the significance of the Koebner phenomenon in lichen planus?
The Koebner phenomenon refers to trauma-induced exposure of dendritic cells to endogenous peptides, stimulating Type 1 interferons and propagating the disease.
What are the familial and non-familial associations of lichen planus?
Familial lichen planus is associated with strong family history and specific HLA haplotypes, while non-familial associations include other HLA types.
What is the most likely diagnosis for a patient with dull red-violet papules on their wrists and legs?
The most likely diagnosis is classic lichen planus. Histological features include hyperkeratosis, wedge-shaped hypergranulosis, and lymphohistiocytic infiltrate.
What is the largest demographic affected by Lichen Planus according to US studies?
The largest predominance of Lichen Planus is found in African American children.
What are the common clinical and histological involvements of Lichen Planus in adults?
In adults, skin involvement occurs in 42-60% of cases, and oral involvement occurs in 17-30% of cases.
What are the characteristics of Annular Lichen Planus?
Annular Lichen Planus is commonly found in the penis/scrotum area.
What distinguishes Linear Lichen Planus from other forms?
Linear Lichen Planus is characterized by post-zygomatic somatic mutations and occurs when dermatomal lines are not followed.
What are the key features of Hypertrophic Lichen Planus?
Hypertrophic Lichen Planus is marked by lesions on the anterior shin, very pruritic symptoms, and thick elevated purple-red plaques.
What is the most common location for Atrophic Lichen Planus?
Atrophic Lichen Planus is most commonly found in the proximal lower extremities and trunk.
What are the characteristics of Vesicobullous Lichen Planus?
Vesicobullous Lichen Planus is secondary to exuberant inflammatory response, more common in lower extremities, and may lead to erosion and ulceration.
What are the symptoms associated with Erosive and Ulcerative Lichen Planus?
Erosive and Ulcerative Lichen Planus is associated with pain and scarring, commonly in the feet and oral cavity.
What are the distinct variants of Follicular Lichen Planus?
Follicular Lichen Planus has three distinct variants: Lichen planopilaris, Frontal fibrosing alopecia.
What are the characteristics of Lichen Planus Pigmentosus?
Lichen Planus Pigmentosus features hyperpigmented dark brown macules in sun-exposed areas, common in darker skin.
What is the most common form of Mucosal Lichen Planus and its characteristics?
The reticular form is the most common, typically asymptomatic, involving the buccal mucosa and tongue.
What are the common sites and symptoms of Esophageal Lichen Planus?
Commonly affects the proximal esophagus, prevalent in middle-aged women, with symptoms like dysphagia and odynophagia.
What is Pseudopelade of Brocq and its clinical significance?
Pseudopelade of Brocq is a clinical syndrome of scarring alopecia characterized by absence of distinct pathologic features.