Dermoscopy of Inflammatory Dermatoses: Psoriasis, LP, Sarcoidosis

Overview / Definition Dermoscopy is a non-invasive imaging technique that enhances the visualization of skin lesions, allowing for improved diagnosis and management of inflammatory dermatoses. Inflammatory dermatoses encompass a broad spectrum of skin conditions characterized by inflammation, including psoriasis, lichen planus (LP), and sarcoidosis. Epidemiology Inflammatory dermatoses vary in prevalence based on the specific condition: Psoriasis: Affects approximately 2-3% of the population, with peaks in incidence occurring in early adulthood and between ages 50-60. Lichen Planus: Prevalence is around 0.1-4%, more common in middle-aged adults, with a slight female predominance. Sarcoidosis: Incidence varies by ethnicity, with higher rates in African Americans and Northern Europeans, typically affecting young adults. Pathophysiology / Mechanism The pathophysiological mechanisms underlying these inflammatory dermatoses involve complex interactions between the immune system and skin cells: Psoriasis: Characterized by a hyperproliferation of keratinocytes and an influx of T cells, leading to the classic plaque formation. Lichen Planus: Involves a lichenoid tissue reaction pattern with a dense band-like infiltrate of lymphocytes at the dermal-epidermal junction. Sarcoidosis: Features non-caseating granulomas resulting from an exaggerated immune response, often triggered by environmental antigens. Clinical Presentation Each condition presents with distinct clinical features: Psoriasis: Well-demarcated red plaques with silvery scales, commonly located on the elbows, knees, and scalp. May exhibit auspitz sign (bleeding upon scale removal). Lichen Planus: Pruritic, polygonal, flat-topped papules, often with a violaceous hue. Can affect mucosal surfaces, leading to oral lichen planus. Sarcoidosis: Skin lesions may appear as erythematous nodules (lupus pernio) or plaques. Systemic symptoms may include respiratory complaints and lymphadenopathy. Diagnosis / Workup Dermoscopy