In many cases of these unusual forms, the pruritus of classic scabies lessens or disappears, the sites of involvement are different, i.e., the scalp, face, back, and nails, and burrows are less apparent. It has been said that scabies is a great imitator. Crusted scabies has been associated with a wide group of disorders, including mental retardation, diabetes mellitus, and immunosuppressed status. New features associated with severe Sarcoptes scabiei infestations exist. Severe forms of infestation develop preferentially in cases of imbalance in host-parasite relationships.
Immune deficiency is one etiologic factor that is being increasingly recognized.
A review of the literature revealed eleven reported cases. 11-16 Scabies in these eleven cases appeared to be more severe than usual, and seven of the patients developed crusted scabies. Atypical or exaggerated type of scabies was observed in only four patients. In our case, systemic and topical corticosteroid therapy aggravated a primary cutaneous involvement, resulting in a severe form of infestation. The role of immunologic mechanisms in limiting the number of scabies mites is not well defined.