Dermoscopy of Parasitic Infections: Scabies and Pediculosis

Overview / Definition Dermoscopy is a non-invasive imaging technique that allows for the examination of skin lesions using a handheld device called a dermatoscope. In the context of parasitic infections, specifically scabies and pediculosis, dermoscopy can reveal specific patterns and structures that help differentiate these conditions from other dermatoses. Epidemiology Scabies and pediculosis are common parasitic infections affecting individuals worldwide. Their prevalence varies by geographic region, socio-economic status, and population density. Key epidemiological points include: Scabies: estimated prevalence ranges from 0.2% to 71% in various communities, with higher rates in overcrowded conditions. Pediculosis (lice infestation): affects approximately 6-12 million children annually in the United States alone, particularly those aged 3 to 11 years. Pathophysiology / Mechanism Both scabies and pediculosis are caused by ectoparasites that infest the human skin or hair. The pathophysiological mechanisms include: Scabies: caused by the mite Sarcoptes scabiei, which burrows into the stratum corneum, leading to an inflammatory response characterized by itching and rash. Pediculosis: caused by Pediculus humanus capitis (head lice) or Pediculus humanus corporis (body lice), which feed on blood and can cause pruritus due to saliva-induced hypersensitivity. Clinical Presentation The clinical manifestations of scabies and pediculosis can often overlap, but there are distinguishing features: Scabies: Intense pruritus, particularly at night. Typical lesions include burrows, papules, and excoriations, often seen on the web spaces of fingers, wrists, and genital areas. Secondary infections may occur due to scratching. Pediculosis: Pruritus of the scalp or body, often accompanied by visible lice or nits. Excoriations and secondary infections may also be present. In severe cases, can lead to dermatitis or lymphadenopathy. Diagnosis / Workup Dermoscopy plays a crucial role in t