Recurrent Bullous Scabies - Journal of Cutaneous Medicine and

CASE REPORT
Recurrent Bullous Scabies
David Serra, José Pedro Reis, Angelina Mariano, Álvaro Machado, and Américo Figueiredo
Background: Scabies is a common infestation that usually presents as a pruriginous eruption consisting of erythematous
papules, nodules, and excoriations. Diagnosis relies mostly on clinical features, including the identification of scabietic burrows.
Several atypical clinical manifestations have been reported; bullous presentations are particularly rare and intriguing.
Objective: A case of recurrent bullous scabies is reported.
Methods and Results: An 87-year-old institutionalized woman developed a pruriginous eruption that mimicked bullous
pemphigoid. Histopathologic examination revealed blistering at the subepidermal level and a mixed inflammatory infiltrate with
numerous eosinophils. Scabies mites were identified on dermoscopy and on skin scrapings, allowing a diagnosis of bullous scabies.
Despite effective treatment with topical lindane, failure to control scabies in her institution led to recurrences of her peculiar
blistering infestation. Immunofluorescence studies were always negative.
Conclusions: These observations underscore the mite’s role in the pathogenesis of blister formation and illustrate current
challenges in scabies’ diagnosis and management.
Antécédents: La gale sarcoptique humaine est une infestation qui se présente habituellement sous forme d’éruption
prurigineuse, caractérisée par des papules érythémateuses, des nodules, et des excoriacions. Le diagnostic se fonde surtout sur
les signes cliniques, notamment l’identification de sillons. Plusieurs manifestations cliniques atypiques ont été rapportées; les
manifestations bulleuses sont particulièrement rares et étranges.
Objectif: Rapporter un cas de gale bulleuse.
Méthodes et résultats: Une femme de 87 ans, résidant dans un établissement de soins, a développé une éruption prurigineuse
évocatrice d’une pemphigoı̈de. L’examen histopathologique a révélé des vésications de l’épiderme et un infiltrat inflammatoire avec
de nombreux éosinophiles. Une dermoscopie et un grattage cutané ont permis d’identifier des mites ce qui a mené au diagnostic de
gale bulleuse. Malgré le traitement efficace au lindane topique, le manque de contrôle de la gale dans l’établissement a produit une
récurrence de l’infestation. Les tests d’immunofluorescence ont tous été négatifs.
Conclusions: Ces observations soulignent le rôle des mites dans la pathogenèse des formations bulleuses et illustrent les défis
actuels auxquels font face les médecins dans le diagnostic et la gestion de la gale.
E REPORT A CASE of recurrent bullous scabies in
an 87-year-old institutionalized woman. She presented for the first time at our department with a 2-month
history of a pruritic eruption. Erythematous papules, along
with excoriations and some blisters, were seen on
examination. Skin scraping examination confirmed scabietic infestation, and topical lindane was prescribed. She
W
From the Dermatology Department, University Hospital of Coimbra,
Coimbra, Portugal.
Presented as an oral free communication at the 17th Congress of the
European Academy of Dermatology and Venereology, Paris, France,
September 17–20, 2008.
Address reprint requests to: David Serra, MD, Dermatology Department,
University Hospital of Coimbra, Praceta Prof Mota Pinto, 3000-075
Coimbra, Portugal; e-mail: [email protected].
DOI 10.2310/7750.2010.09028
# 2010 Canadian Dermatology Association
missed her follow-up appointment and was reobserved
only 3 months later.
At that time, she presented a blistering, pruriginous
eruption mimicking bullous pemphigoid, with tense
bullae, erosions, and crusts (Figure 1). No scabietic
burrows were found. Skin biopsy revealed blistering at
the subepidermal level, with an inflammatory infiltrate in
the upper dermis composed of neutrophils and eosinophils
(Figure 2). Direct immunofluorescence (DIF) studies were
negative. Diagnostic workup also included blood studies
that revealed eosinophilia (1,000/mL; normal range 0–500 mL)
and a high IgE titer (812 IU/mL; normal , 100 IU/mL). She
was treated with topical clobetasol propionate, and her
condition improved during the first 2 weeks of treatment.
However, 1 month later, she complained of intense pruritus
and presented numerous typical scabietic burrows.
Application of topical lindane, followed by the regular use
of emollients, allowed marked improvement.
Journal of Cutaneous Medicine and Surgery, Vol 14, No 4 (July/August), 2010: pp 175–177
175
176
Serra et al
Figure 1. Tense bullae in the left arm
(left) and the left foot (right).
Six months later, she had a scabietic reinfestation, with
intense pruritus, typical scabietic lesions, and some tense
blisters. Scabies mites and eggs were once again identified
in skin scrapings; sample collection was guided by
dermoscopy (Figure 3). Immunofluorescence studies
(including indirect immunofluorescence) remained negative. She was once more treated with lindane. Vigorous
measures were implemented at her institution to avoid
further outbreaks or reinfestations.
Since then, she has been asymptomatic for more than a
year of follow-up.
Figure 2. Blistering at the subepidermal level and a dermal infiltrate with
eosinophils (hematoxylin-eosin stain, 3 100 original magnification).
Discussion
Bullous lesions are very rare in scabies.1 A few cases have been
reported in which scabies mimicked bullous pemphigoid.1,2
Recurrent bullous scabies, as seen in the present case, is
particularly interesting. The recurrence of a blistering
eruption raised suspicion of an underlying autoimmune
blistering disorder, such as bullous pemphigoid. However,
immunofluorescence studies were always negative and
against this possibility. Furthermore, we did not need any
immunosuppressive therapy to control her blistering
disease. Clobetasol treatment was temporarily used and
indeed stopped the blistering process while uncovering the
true nature of the disease. In fact, antiscabietic treatment
cured both the infestation and the blistering eruption,
providing a strong argument in favor of the mite’s role in
the pathogenesis of bullae formation.
The mechanism of blister formation in scabies remains
unexplained. Scabies-induced hypersensitivity mediated by
histamine and eosinophils has been proposed as a putative
mechanism.3 Another theory states that the parasite might
induce an autoimmune blistering reaction similar to that
seen in bullous pemphigoid. Enzymes released by the mites
could damage the basement membrane zone and expose
antigens that on physiologic conditions are not detected by
the immune system, thereby allowing the development of
autoimmunity.4 Indeed, immune deposits have been
occasionally found on DIF studies of scabietic lesions
from otherwise healthy patients and from patients with
bullous scabies.1,5 However, the pathogenic role of such
Recurrent Bullous Scabies
177
Figure 3. The ‘‘jet with contrail’’ or
the ‘‘circumflex’’ sign (arrows), seen
on dermoscopy (left), marks the spot
where mites and eggs can be found,
allowing successful collection of skin
scrapings and a higher rate of positive
microscopic examinations: Sarcoptes
scabiei and an egg (right).
deposits is still unclear, and they were not detected in the
majority of cases.
Diagnosing scabies is not always a straightforward task.
Dermoscopy is a helpful technique.6 It can be easily
performed in everyday practice to obtain quick diagnostic
confirmation. We also use it to locate mites, thus allowing
a higher rate of positive skin scraping examinations.
Microscopic examination of skin scrapings is timeconsuming but remains useful to establish a definite
diagnosis, especially in difficult cases.
Finally, our patient’s successive reinfestations illustrate
how challenging it can be to control scabies in institutional
settings. Old or overcrowded facilities are particularly
prone to epidemics. Inadequate implementation of disease
control measures and the need to treat a high number of
contactants explain why failure is so frequent in such
settings. The morbidity and very high costs resulting from
outbreaks underscore the value of an effective first-time
approach in such situations.7
Acknowledgment
Financial disclosure of authors and reviewers: None
reported.
References
1. Shahab RKA, Loo DS. Bullous scabies. J Am Acad Dermatol 2003;49:
346–50.
2. Viraben R, Dupre A. Scabies mimicking bullous pemphigoid. J Am
Acad Dermatol 1989;20:134–6.
3. Haustein UF. Bullous scabies. Dermatology 1995;190:83–4.
4. Veraldi S, Scarabelli G, Zerboni R, et al. Bullous scabies. Acta
Dermatol Venereol 1996;34(5 Pt 2):878–9.
5. Frentz G, Veien NK, Eriksen K. Immunofluorescence studies in
scabies. J Cutan Pathol 1977;4:191–3.
6. Dupuy A, Dehen L, Bourrat E, et al. Accuracy of standard
dermoscopy for diagnosing scabies. J Am Acad Dermatol 2007;56:
53–62.
7. Scheinfeld N. Controlling scabies in institutional settings. A review of
medications, treatment models and implementation. Am J Clin
Dermatol 2004;5:31–7.