International Academy of Cosmetic Dermatology
Scabies, also known as the seven year itch, is a dermatologic condition caused by infestation of the mite Sarcopetes scabiei var hominis. The female mite is located in the upper layers of the epidermis, just below the surface. Intense pruritus, usually worse in the evening, is the main symptom.
Burrows, a characteristic skin lesion associated with scabies, are small superficial canals within the top layers of the skin. They are most often located in the web spaces between the fingers. Mites, eggs, or fecal concretions may be present in burrows.
Other skin lesions associated with scabies include blisters (in newborns), excoriations, hyperkeratosis and scaling (particularly in immunosuppressed patients with the ‘crusted’ variant of the condition), and red nodules (especially on the penis and scrotum).
Scabies is transmitted from one individual to another by long-term or frequent skin-to-skin contact with a mite-infected person. The diagnosis needs to be considered in patients who present for an evaluation of pruritus—especially if other members with whom they live also itch.
The diagnosis can be confirmed in the office during the patient’s visit by finding either mites, eggs, or fecal concretions on a mineral oil preparation prepared from skin scrapings from suspected clinical lesions or by identification of mite parts in the stratum corneum on microscopic examination of a lesional biopsy specimen can also establish the diagnosis. Often times, the clinical presentation permits a fairly sure diagnosis on inspection.
Topical application of permethrin 5% cream is usually used for the treatment of scabies. Alternative topical agents include crotamiton 10% cream and precipitated sulfur 6% in petrolatum. Oral treatment with ivermectin has also been found to be effective. In addition to the patient, empiric treatment of other family members and housemate should be considered.
Philip R. Cohen, MD
Bellaire, TX, USA