A report describes a case of a man aged 45 years with a known case of psoriasis in remission who presented with generalized erythema and scaling for 1 month. He used self-prescribed steroids, antibiotics and topical salicylic acid formulations that caused only temporary relief. 

Examination revealed diffuse, hyperkeratotic, yellow scales on an erythematous base, covering 95% of the body surface area. He received a provisional diagnosis of psoriatic erythroderma. 

Ten percent potassium hydroxide (KOH) mount of scales revealed 5 to 6 scabies mites/high power field. His serum cortisol level was significantly lowered. His other investigations were normal. He received a diagnosis of erythroderma secondary to crusted scabies with iatrogenic Cushing′s disease (due to self-prescribed steroid). 

The patient received oral ivermectin (200 µg/kg) on Days 1, 2, 8, 9, and 15, and 5% permethrin cream daily for 7 days, then twice weekly until there were no mites on KOH mount. His hyperkeratotic plaques cleared in 3 weeks. For iatrogenic Cushing′s disease, he received physiological doses of tablet prednisolone 5 mg in the morning and 2.5 mg in the evening, as advised by the endocrinologist, and he was followed up in endocrinology OPD.

Source: Devi GC, Hazarika N. Erythroderma secondary to crusted scabies. BMJ Case Rep. 2021;14:e248000.