++
Scabies is a common condition in children caused by an infestation
of the Sarcoptes scabiei mite. Scabies is primarily
contracted by direct contact with an infested person; therefore,
the acquisition and spread of scabies, particularly from parents
to children, or mother to infant, occurs with relative ease. The
highest prevalence is in children younger than 2 years. The disease
affects all age groups, races, and social classes; however, poor socioeconomic
conditions, in particular, crowding, lack of proper hygiene, and
immunosuppression, are risk factors for the disease. The female
mite burrows through the skin, leaving behind a trail of debris,
eggs, and feces. Clinical findings result from hypersensitivity and
irritation to the mite and mite products. Scabies infestation is
extremely pruritic and notoriously worse at night. Frequently, other family
members also complain of itching.
++
The distribution of scabies lesions is helpful in making the
diagnosis. In infants, the insteps of the feet are commonly affected,
often with vesicles or pustules. An important diagnostic clue is
an infant who is vigorously rubbing his or her feet together in
an attempt to relieve itching. Unlike older children, infants commonly
have involvement of the palms and soles, axillae, and scalp. The
characteristic distribution of scabies lesions at any age is wrists,
finger web spaces, and waistline. Pruritic, nodular lesions of the
area around the nipples, umbilicus, axillae, or genitalia are also
suspicious for scabies. Lesions in children are generally more inflammatory
than in adults and are often vesicular or bullous. A unique clinical
feature is the finding of the scabies burrow, which, although difficult
to find in children, can be seen as a gray threadlike trail of scale
on the skin.
++
Clinical variants of scabies may present diagnostic difficulties.
For example, scabies incognito occurs when treatment with topical
or oral glucocorticoids masks the characteristic symptoms and signs
of scabies. Lesions may be atypical in both appearance and distribution and
are generally more widespread. Crusted (Norwegian) scabies is a
highly contagious form of scabies often seen in immunocompromised
or debilitated, often institutionalized, patients. Widespread scale
and crust formation is present, which may be remarkably thick over
the palms, soles, and nails. Nodular scabies presents with discreet,
orange-red nodules affecting the axillae and groin. Similar to the
tick granuloma, nodules most likely represent a hypersensitivity reaction
to retained mite parts or antigens. Lesions may persist for weeks
to months and are often resistant to therapy.1
++
The scabies preparation is a simple and rapid means of establishing
the diagnosis of scabies. Using a mineral oil–coated Joseph
knife or sterile scalpel blade, multiple lesions are scraped. It is
ideal to perform this procedure on the child’s caregiver
if he or she has skin findings suspicious for scabies. The best
lesions for diagnosis are burrows, vesicles, and unexcoriated papules, and
the best scrapings obtain the material underneath the tops and crusts
of lesions. The material obtained is then transferred onto a glass
slide and examined microscopically ...