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

Abstract

Scabies surrepticius is a unifying term that represents non-classical presentations of scabies mite infestation. A patient with scabies surrepticius is described: a man with scabies masquerading as prurigo nodularis. The 91-year-old man had metastatic prostate cancer and presented with diffuse pruritic nodules. Prurigo nodularis was suspected; however, the biopsy revealed scabies mites in the stratum corneum. He was successfully treated with topical permethrin 5% cream and oral ivermectin. In addition, the features of a woman with scabies mimicking systemic lupus erythematosus are summarized. The 47-year-old woman had idiopathic thrombocytopenic purpura and presented with malar erythema and a positive antinuclear antibody (titer 1:320). A diagnosis of systemic lupus erythematous was entertained until skin scraping and mineral oil preparation revealed scabies mites; she was successfully treated with oral ivermectin. In conclusion, Sarcoptes scabiei infestation can present with atypical clinical morphology and an absence of classical lesions such as burrows conventionally distributed in the interdigital web spaces, volar wrists, periumbilical area, or genitalia. Scabies surrepticius is a term that has been designated to describe these unusual presentations. Prurigo nodularis and systemic lupus erythematosus can be added to the litany of conditions masquerading as scabies and are included amongst the guises of scabies surrepticius.