An itchy rash with multi-regional crusts and scalp erosion

• Published in: BMJ (Online) 2023-10, Vol.383, p.e076501-e076501
• Main Authors: Yin, Shu-Jun, Zhong, Yue-Hong, Fan, Yi-Ming
• Format: Article
• Language: English
• Subjects: Albendazole; Atopic dermatitis; Bullous pemphigoid; Case reports; Dermatitis; Endgames; Erythema; Ivermectin; Parasitic diseases; Permeability; Permethrin; Pruritus; Psoriasis; Salicylic acid; Scabies; Seborrheic dermatitis
• ISSN: 1756-1833; 1756-1833
• DOI: 10.1136/bmj-2023-076501

(D) Dermoscopy of the left postauricular area showing approximately 30 brownish triangular structures located at the distal end of whitish curvilinear/straight burrows (“jet with contrail” sign, arrowheads) and one brownish adult mite (arrow) on the white scales (original magnification ×60) Questions What are the differential diagnoses? Clinical differentials include crusted scabies, psoriasis, seborrheic dermatitis, atopic dermatitis, relapsing bullous pemphigoid, and drug eruption.12 Dermoscopy is a simple and efficient way to diagnose scabies by visualising the “jet with contrail” sign (corresponding to the mite’s pigmented anterior part and linear burrow, respectively)123 and active mites.4 2. Topical permethrin is the treatment of choice for classic scabies, while combined use of topical permethrin, keratolytics (urea or salicylic acid ointment), and oral ivermectin is first line therapy for crusted scabies.135 Debulking crusts can decrease mite burden and increase permeability of topical scabicides.36 Albendazole, an anti-helminthic and antiprotozoal agent, offers an alternative treatment for crusted scabies when oral ivermectin is unavailable.6 Household contacts should be treated concurrently with topical permethrin or oral ivermectin, even if asymptomatic.34 Clothing, bedding, and other household items should be washed at above 50°C, machine dried, or sealed in plastic bags for at least one week.5 Learning points Crusted scabies is a severe and highly contagious form of scabies.