Crusted scabies of the scalp in dermatomyositis patients: three cases treated with oral ivermectin

Background Cutaneous features in the scalp area among adult patients are rarely considered as a manifestation of scabies. Methods Three patients with clinical and laboratory data of dermatomyositis with scalp involvement (fulfill three or four of Bohan and Peter's criteria), of 4 years, 8 months, and 3 years duration, were seen at our department between 1995 and 1996. For relapses of ordinary scabies, they were treated repeatedly with local scabicide with temporary effect. After a symptom-free period during the treatment of dermatomyositis with corticosteroids and azathioprine, they developed diffuse redness with scales and crusts on the scalp areas. Light microscopy examination of material taken from these crusts showed an abundance of live mites. Results All patients were successfully cured of scabies with a twice oral dose of 200 mu g/kg ivermectin within 8 days. Conclusions Our patients with crusted scabies of the scalp and dermatomyositis prompted us to change our standard diagnostic and therapeutic regimens. Fascinating features included mimicry of scabies in patients with dermatomyositis, location of parasites on the scalp, suppressed cell-mediated immunity and successful cure of mange by ivermectin.