Crusted (Norwegian) scabies
Overview
- Crusted scabies (Norwegian scabies) = extreme variant in immunosuppressed individuals (HIV, hematologic comorbidity, glucocorticoid therapy).
- Highly contagious due to millions of mites; widespread hyperkeratotic plaques, pruritus often reduced.
First step: isolation
Before any work-up or treatment comes immediate contact isolation — with a mite burden of up to several million, brief skin contact as well as contaminated linen and surfaces suffice for transmission. This is why crusted scabies is the classic trigger of outbreaks in care homes and hospitals.
- Single room, gowns and gloves for every contact, rigorous processing of linen and surfaces; contacts — fellow residents, nursing staff, relatives — are treated simultaneously (see section 9).
Confirming the diagnosis: direct preparation from the scales
In crusted scabies the laborious search for burrows is unnecessary: in a microscopic direct preparation of detached horny scales a single scale already contains numerous mites, eggs and scybala.
- Practical: remove scales with a scalpel or curette, place them in potassium hydroxide or immersion oil on a slide, apply a coverslip and examine; dermoscopy and adhesive tape sampling are complementary.
- Look for the cause: HIV test, haematological work-up, drug history (glucocorticoids, immunosuppressants), nursing and nutritional status.
Differential diagnoses
- Psoriasis vulgaris (plaque psoriasis)
- Impetigo
- Mycosis fungoides
- Pityriasis rubra pilaris
- Ichthyosis
- Scabies
- Ecthyma
- Pityriasis rosea
Practise Crusted (Norwegian) scabies in the app
Flashcards with spaced repetition, exam questions and spot-the-diagnosis on this topic – in DermaFuchs, free of charge.
In the DermaFuchs app: 1 flashcards · 3 clinical images
Open in browser Download on the App StoreMore parasitic skin diseases
- Demodicosis
- Filariasis
- Cutaneous leishmaniasis
- Cutaneous larva migrans
- Pediculosis capitis
- Caterpillar dermatitis caused by oak processionary moth (Thaumetopoea processionea)
- Scabies
- Tungiasis
Note: This page is intended for medical education and does not replace diagnosis or treatment decisions in individual cases. Treatment and follow-up content is available in the app.