Bullous Scabies: Clinical, Dermoscopic, and Pathologic Characteristics of Ten Patients

Abstract

Bullous scabies (BS) is a rare atypical clinical variant of scabies and is easily confused with bullous disorders. The diagnosis of BS is always a challenge, and physicians often misdiagnose BS patients. Patients with BS admitted from 2012 to 2020 were enrolled in this study. The clinical, dermoscopic, and pathological characteristics of the patients were analyzed retrospectively. Ten patients with BS were enrolled in this study. Seven of the 10 patients were male. The bullae were most commonly found on the thighs and arms (80% of patients). Only 30% of patients (3/10) tested positive for mites and/or eggs by the initial skin scraping, but 100% (5/5) of the patients who received dermoscopy tested positive. Among these 10 patients, only five received a skin biopsy. Subepidermal (4/5) and intraepidermal (1/5) bullae with eosinophil and neutrophil infiltration were observed in five patients. Direct immunofluorescence (DIF) indicated linear deposition of IgG in the basement membrane zone in three patients. Physicians should consider the possibility of BS in patients with blisters, pruritus, and poor response to corticosteroids. Dermoscopy should be prioritized for the differential diagnosis of BS to exclude other bullous disorders. Finally, a biopsy should be performed on each patient with bullae.

Figure 1.

Bullous scabies. (A) Bullae and scabs on the thighs. (B) Bullae and papules on the periumbilicus. (C) Bullae and papules on the left arm. (D) Erythema, papules, scales, and scabs on the lower extremities. This figure appears in color at www.ajtmh.org.

Figure 2.

Histopathology of Bullous scabies. (A) Subepidermal blisters with inflammatory cell infiltration. (B) Inflammatory cells in the subepidermal blister including neutrophils and eosinophils. (C) Intraepidermal blisters and spongiosis with inflammatory cell infiltration. (D) Inflammatory cells in the intraepidermal blister including neutrophils and eosinophils. (E) Direct immunofluorescence results showing linear deposition of IgG in the basement membrane zone. (F) An image of scabies mites on dermoscopy. The dark triangles (black arrow) indicate the mites’ mouthparts. This figure appears in color at www.ajtmh.org.