Bullous Scabies Mimicking Bullous Pemphigoid

Abstract

Scabies is an infestation caused by Sarcoptes scabiei and characterised by polymorphous lesions that may include burrows, papules, nodules, excoriation and crusts. Vesicular and bullous lesions are rather rare. Several diseases may be confused with scabies. We report a case of bullous scabies which, on the basis of the clinical and histopathological picture, mimicked bullous pemphigoid. Direct and indirect immunofluorescence were negative. Bullae recurred and persisted despite systemic corticosteroids. The patient was successfully treated with 5% permethrin and remained disease free for up to 12 months of follow-up.

Increased risk of pemphigoid following scabies: a population‐based matched‐cohort study

“…Scabies has multiple presentations and has been reported by numerous studies to mimic pemphigoid . One such atypical manifestation most common among the elderly are bullous lesions known as bullous pemphigoid‐like eruptions .…”

A case of crusted scabies with a bullous pemphigoid‐like eruption and nail involvement

“…Clinically, it is difficult to distinguish between bullous pemphigoid and scabies with bullous pemphigoid symptoms, especially when the skin scrapings do not reveal any mites or eggs 3 . Even when the skin scrapings are positive, there is still the possibility of scabies and concomitant bullous pemphigoid to consider.…”

“…Several explanations have been given in the published work about the pathophysiology of blister formation in these atypical cases of scabies. One author suggested that the mites or their lytic secretions may cause the alteration or the release of bullous‐pemphigoid‐antigen (BP antigen), leading to an immunological response and resulting in the production of anti‐basement membrane zone antibodies, as seen in bullous pemphigoid 3 . Another author speculated that the mite itself may act as an antigen which cross‐reacts with the BP antigen to stimulate the production of autoantibodies, 11 but neither explanation is complete and further evaluation is necessary.…”

“…In most cases, elderly patients show symptoms of classic scabies but it is not uncommon for them to develop crusted scabies, also known as Norwegian scabies, and in turn become a source of infection within their hospital or nursing home. There are a few reports of bullous scabies resembling bullous pemphigoid 3 …”

A Review of Scabies: An Infestation More than Skin Deep

“…In developed countries the differential diagnosis should include common pruritic dermatoses such as psoriasis, atopic eczema and lichen planus. If blistering is present, then bullous pemphigoid [45, 46] and dermatitis herpetiformis should be considered. Additionally, there appears to be an increased risk of developing psoriasis following scabies [47].…”