Atypical Scabies Presenting as Annular Plaques: A Case Report and Review of the Literature.

Scabies is a highly contagious parasitic infestation caused by Sarcoptes scabiei var. hominis, commonly presenting with pruritic lesions such as papules and burrows. While typical scabies lesions are well-documented, atypical presentations can complicate diagnosis. This case report describes an unusual manifestation of scabies presenting as annular plaques. A 50-year-old male with no significant medical history presented with a pruritic rash, including well-defined annular plaques on his thighs. Dermoscopic examination revealed the characteristic "deltaplane" sign and a translucent mite body, consistent with scabies. UV dermoscopy further confirmed the diagnosis with the "ball sign," highlighting the mite's fluorescence. The patient received two doses of oral ivermectin, leading to the complete resolution of pruritus and lesions within 10 days. The rapid resolution and clinical findings led to the diagnosis of atypical scabies. This case highlights the importance of considering atypical scabies in the differential diagnosis of annular plaques and underscores the value of dermoscopy, particularly UV dermoscopy, in enhancing diagnostic accuracy and treatment monitoring in scabies.