A 75 year-old Caucasianman presentedwith an itchy erythrodermic dermatosis showing scaling in the arms and in the gluteal region (Fig. 1A, upper panel). Hewasundergoing amultidrug therapywith ciprofloxacin and salmeterol for a BPCO exacerbation, timolol for a glaucoma, citalopram and lormetazepam for anxious-depressive symptoms, and aspirin for stroke prevention. He had been surgically treated 4 years before for a prostatic adenocarcinoma (pT2c N0 at staging) and was recently diagnosed with a superficially invasive transitional carcinoma of the bladder. Due to the worsening erythroderma, he underwent a skin biopsy with a clinical suspect of erythrodermic psoriasis or adverse drug reaction. On histology, the skin showed only a mild perivascular inflammatory infiltrate of the dermis. The patient was then treated with methylprednisolone without any improvement. Therefore, a second histological examination was performed with three punch biopsies on the scaly sites. On histology, many mite parts and eggs were identified in the stratum corneum on a spongiotic epidermal background (Fig. 1B, lower panel). In the dermis, a mild perivascular inflammatory infiltrate was present.