scabies

Oral ivermectin treatment for an infant with crusted scabies

Posted by

0


A fully vaccinated 4-month-old girl with normal development was referred to our dermatology clinic for an intensely itchy, diffuse papular rash that had been present for 3 months. Her family physician had initially diagnosed eczema and treated with betamethasone valearate 0.05% ointment, but later diagnosed impetigo and treated with topical and systemic antibiotics, which resulted in no improvement. She improved mildly after 2 courses of 5% permethrin and 0.1% (w/w) mometasone lotion for suspected scabies.

When the patient visited our clinic, we saw widespread polymorphous eruptions consisting of erythematous papules, pustules and dermatitic plaques on her back, posterior neck, scalp and inguinal folds. Her palms had a pustular appearance, and her soles had erythematous, crusted, hyperkeratotic plaques (Figure 1). Dermoscopy showed central crusting and furrows, suggestive of crusted scabies. We performed a skin biopsy because of the patient’s poor response to permethrin, which confirmed crusted scabies. We prescribed oral ivermectin (1 200 μg/kg dose per wk) for 3 weeks to both her and family members living in the same household. We also prescribed betamethasone 0.1% ointment twice daily and oral rupatadine (1 mg) daily. We asked the infant’s parents to clean household fabrics at high temperatures or to bag items for 2 weeks to avoid reinfestation. Two months later, she had fewer erythematous papules and pustules.

Figure 1:

Photographs of a 4-month-old infant with crusted scabies, showing (A) diffuse, crusted and hyperkeratotic scales that involved the entire plantar surface bilaterally, and (B) diffuse, erythrodermic papules and pustules, with desquamation and papulonodular lesions, that affected the leg and popliteal fossa.

Crusted scabies, or Norwegian scabies, is an uncommon, highly contagious form of the condition, with excessive proliferation of Sarcoptes scabiei var. homini on the skin.1 It is seen most commonly in immunocompromised children and does not usually colonize healthy infants.2 Oral ivermectin has been approved for the treatment of scabies in children weighing more than 15 kg, but is currently used in infants off label. A recent study of 170 infants aged 1–64 months found oral ivermectin to be effective, with no severe adverse effects; therefore, it can be a treatment option in patients for whom standard treatment with topical permethrin and management of post-scabetic itch fails to control symptoms.

Nickel allergic contact dermatitis

Posted by

0


A 41-year-old man presented to the dermatology clinic with a 1-month history of erythematous, pruritic papules on the abdomen. The periumbilical skin had 2 symmetric erythematous plaques with overlying scaly, hyperkeratotic tissue and eczematous papules (Figure 1A). The lesions were confined to the skin in contact with a metallic belt buckle purchased 3 months before. Positive patch test (++) for nickel sulfate (5.0%) in petroleum confirmed contact dermatitis to nickel (Appendix 1, available at www.cmaj.ca/lookup/doi/10.1503/cmaj.220260/tab-related-content). We prescribed a 7-day course of mometasone furoate (0.1%) cream, which led to a substantial improvement (Figure 1B). We recommended that the patient avoid future contact with nickel-containing accessories and use brass or plastic fasteners, belts and buckles instead.

Figure 1:

Nickel allergic contact dermatitis: (A) Periumbilical skin of a 41-year-old man with 2 erythematous plaques with overlying pruritic and eczematous papules. (B) A marked improvement was observed after 1 week of using a topical corticosteroid.

A meta-analysis of 20 000 people from the general population who were patch tested confirmed a 20% prevalence of contact allergy, with nickel being the most common allergen (11.4%).1 Prevalence is higher in women and people with atopic disorders.2 Nickel allergic contact dermatitis results from a type IV cutaneous hypersensitivity reaction, although symptoms can occur within the first 30 minutes of exposure.3 Prolonged contact with the skin, sweat and friction can induce subclinical maceration and release of nickel into the skin.

Differential diagnoses include scabies, impetigo, psoriasis, inflammatory dermatoses, mycosis fungoides, tinea corporis, atopic dermatitis and fixed drug eruptions.4 Presentation varies from mild dermatitis with pruritus, deep erythema with oozing and papulation, to a systemic reaction with generalized idiopathic hypersensitivity. Patch testing can confirm the etiologic agent, and skin biopsy may help if the diagnosis is uncertain. Standard treatment is to remove the source object and prescribe topical corticosteroids.5 Calcineurin inhibitors (i.e., tacrolimus) can be considered for steroid-resistant cases, and oral steroids or antihistamines to aid in symptom resolution.

Clinical images are chosen because they are particularly intriguing, classic or dramatic. Submissions of clear, appropriately labelled high-resolution images must be accompanied by a figure caption. A brief explanation (300 words maximum) of the educational importance of the images with minimal references is required. The patient’s written consent for publication must be obtained before submission.