Scabies Surrepticius: Scabies Masquerading as Pityriasis Rosea

Abstract

Scabies, a mite infestation caused by 'Sarcoptes scabiei', most commonly presents as pruritic linear burrows where the mite has invaded the skin. Scabies variant such as bullous, crusted, hidden, incognito, nodular and scalp-mimic the other conditions. In addition, atypical presentations of scabies can masquerade as dermatitis herpetiformis, ecchymosis, Langerhans cell histiocytosis, systemic lupus erythematosus, urticaria, and urticaria pigmentosa. A 59-year-old male presented with non-pruritic papulosquamous plaques on his chest, abdomen, and back resembling lesions of pityriasis rosea in morphology and distribution. The complete cutaneous examination also demonstrated burrows on his finger webs. A mineral oil preparation of skin scrapings showed scabies mites, ova, and scybala. His infestation resolved after the treatment with topical permethrin 5% cream and oral ivermectin 15 mg on days one and eight. In conclusion, scabies surrepticius is a term that has recently been established to unify not only the numerous variants but also the atypical presentations of scabies. The inaccurate diagnosis of scabies infestation can lead to increased medical costs and the side effects of unnecessary tests and the treatment. Pityriasis rosea-like scabies can be added to the list of atypical presentations that are included under the unifying designation scabies surrepticius.

Classic and Non-classic (Surrepticius) Scabies: Diagnostic and Treatment Considerations

“…In 2017, the term scabies surrepticius was proposed as a designation to encompass all of the atypical presentations of scabies. Subtypes of scabies surrepticius includes not only crusted scabies, but also other variants: bullous, hidden, incognito, nodular, scalp-related and other less common morphologies that mimic dermatitis, dermatitis herpetiformis, ecchymoses, Langerhans cell histiocytosis, pityriasis rosea, prurigo nodularis, systemic lupus erythematosus, urticaria and urticaria pigmentosa [10][11][12][13].…”

Nodular scabies: a persistent nodular eruption

“…Nodular scabies can persist long after the initial infestation is treated and can be difficult to eradicate. Atypical scabietic infestations can present as mimics of numerous other cutaneous conditions, including but not limited to Langerhans cell histiocytosis [6], pityriasis rosea [7], or bullous pemphigoid [8]. Nodular scabies in particular has been well described as a mimic of cutaneous mastocytosis, as it can commonly present with a positive Darier sign [9].…”

Scabies presenting as cutaneous nodules or malar erythema: reports of patients with scabies surrepticius masquerading as prurigo nodularis or systemic lupus erythematosus

“…In contrast to the classical manifestations of scabies, unusual presentations can occur, mimicking other conditions. These various subtypes of scabies have more recently been referred to as scabies surrepticius (Box 1), [3,4].…”

“…However, infestations with scabies can present with unusual morphologies lacking typical lesions or clinical clues to the underlying parasite. In this setting, the infestation has been referred to as scabies surrepticius (Box 1), [3,4]. A man whose scabies mimicked prurigo nodularis is described, and the features of a woman with scabies mimicking systemic lupus erythematous are reported.…”