Scabies with bullous pemphigoid - like eruption

Introduction

The itch mite, Sarcoptes scabiei var humanus, discovered in 1687, makes scabies one of the first disease with a known cause.[1] The infestation with Sarcoptes scabiei often is masquerading as and mimicking different skin disease "the great imitator in dermatology".[2] Vesicles are common in children with scabies but uncommon in adults. Some patients with scabies develop bullae concomitantly with, or subsequently after, the occurrence of scabetic lesions. Here we report a case of bullous scabies resembling bullous pemphigoid in a 10-year-old boy.

Case Report

A 10-year-old boy studying and staying in Madresa presented with generalized, nocturnal itching and multiple blistering skin disease for 10 days. There was history of generalized itching in other inmates of madresa. Clinical examination revealed multiple vesiculobullous lesions on face, chest, abdomen, back, webs of fingers and genital region. Bullae were tense in nature and there was collection of pus at some places.

Routine hemogram examination was normal. Histopathological findings epidermis. The blister cavity contained inflammatory cells mainly polymorphs, eosinophils and few lymphocytes. Patient was treated with topical gamma benzene hexachloride and systemic and local antibiotics.

Discussion

Most dermatologists are familiar with the diagnosis of scabies. Our patient was unusual because most of his lesions were vesiculobullous. In our patient, short duration of illness, nocturnal pruritus, similar complaints in other inmates, distribution of bullous lesions and histopathology showing subepidermal blister with intact epidermis forming its roof encouraged us to label the patient as having bullous scabies. How the mite induces vesicles/bullae formation is not well understood. Viraben and Dupre suggested that blisters were related to type I hypersensitivity induced by scabies mites.[1] Most case reports have described negative/nonspecific findings with direct immunofluorescence.[3] Slawsky et al demonstrated intense homogenous band of IgG and C3 deposition in the basement membrane zone of bullous lesions.[3] Konishi et al show that two scabetic patients bullous eruptions had circulatory antibodies against BP180 and/or BP230 as determined by Western blotting analysis. This is the first report to demonstrate that at least some of the bullous eruptions occurring in scabetics are true bullous pemphigoid.[4] Because of lack of facility, immunofluorescence studies could not be carried out in our case. The physiopathologic mechanism of bullous lesions in scabies remains speculative and needs further evaluation.