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.

Keywords: feces; mite; ova; pityriasis; rosea; scabies; scybala; surrepticius.

Figure 1. Scabies surrepticius: scabies mimicking pityriasis rosea.

Scaly papules and plaques on the back and buttocks (A), the right flank (B), and the right abdomen (C) of a 59-year-old African American male. The skin lesions are distributed along the lines of Langer (indicated by arrows).

Figure 2. The burrows of the Sarcoptes scabiei mite infestation.

The distant (A and C) and closer (B and D) views of the burrows (arrow) on the right thumb and the web spaces between the left fourth and fifth digit.

Figure 3. Sarcoptes scabiei mite.

The examination of the mineral oil preparation of the skin lesion scrapings using a light microscope shows a Sarcoptes scabiei mite (indicated by the arrow).