Crusted scabies (otherwise known as Norwegian scabies) is an uncommon, highly contagious infestation that affects patients with a weakened immune system. The infestation presents with hyperkeratoticplaques with yellowish crusts located on the limbs, trunk, ears and eyebrows.
Histology of crusted scabies
In crusted scabies, there are numerous mites within the stratum corneum. The stratum corneum is markedly thickened and there is epidermalacanthosis (figures 1, 2).
Figure 1
Figure 2
Special studies for crusted scabies
None are generally needed.
Differential diagnosis of crusted scabies
Compared with conventional scabies, the mites are far more numerous and associated with hyperkeratosis.
References
Weedon's Skin Pathology (Third edition, 2010). David Weedon
Yélamos O, Mir-Bonafé JF, López-Ferrer A, Garcia-Muret MP, Alegre M, Puig L. Crusted (Norwegian) scabies: an under-recognized infestation characterized by an atypical presentation and delayed diagnosis. J Eur Acad Dermatol Venereol. 2014 Nov 26. PubMed