Disseminated bullous eruptions: bed bugs!

Dear Editors, A 39-year-old man presented with a five-day history of numerous, tense bullae filled with serous, partly hemorrhagic fluid, localized particularly on the extensor sides of the extremities, abdomen and back (Figure 1a–d). The head, palms, soles, and mucous membranes were not affected. The disseminated bullous eruption was accompanied by severe pruritus and mild pain, whereas fever and malaise were denied. Initially, several differential diagnoses were considered based upon the clinical presentation (Table 1). Some were excluded due to the absence of known allergies and comorbidities, lack of prior medication intake, and the available anamnestic information. Blood examinations revealed moderately elevated C-reactive protein and lactate dehydrogenase levels, otherwise blood counts and chemistry were within normal ranges. Total and specific IgE levels against the most common inhalant and nutritional allergens and immunological parameters, including antinuclear antibodies and subsets, autoantibodies to BP180, BP230, desmoglein-1 and -3, envoplakin, and collagen VII, were inconspicuous. Histopathological evaluation of lesional skin (Figure 1e,f), direct and indirect immunofluorescence tests were not indicative of an autoimmune bullous disorder. Herpes and varicella zoster virus DNA were not detected. However, during the course of the diagnostic procedures, the patient returned with a jar containing insects he had discovered in his home (Figure 2a,b). As the insects were identified as common bed bugs, Cimex (C.) lectularius, the extensive disseminated bullous eruptions were finally classified as bullous arthropod bite reactions. Bed bugs are wingless, obligate hematophagous ectoparasites belonging to the family Cimicidae. C. lectularius, the common bed bug, is found in subtropical and temperate regions, C. hemipterus, the tropical bed bug, predominantly inhabits tropical and subtropical regions.1 Bed bugs have accompanied human populations for several millennia. However, within the past 25 years, both species have expanded to regions outside their traditional geographic areas and resurgences of bed bug infestations have been reported worldwide.1, 2 The supporting factors include increasing travel activities, flourishing international commerce, decreased awareness in the population, ineffective pest-control measures and growing resistance of bed bugs to insecticides.1-3 Beg bugs are about 1–7 mm in size and have an average life span of 4–6 months, during which females lay 50–200 eggs.2, 4 All developmental stages require blood from humans or, alternatively, other mammals or birds. During the day, the insects hide in cracks and crevices, behind wallpapers, in seams of mattresses, bed-, window- and door frames, and furniture. At night they feed at a frequency of once every 3–5 days, but survival for many months without a blood meal has been reported.2 Bed bug bites are painless and the resulting skin reactions highly variable.2, 4 While 10%–90% of individuals have been reported to not show any visible reactions, others develop maculopapular and erythematous lesions immediately or after a latency of up to 10 days.4 The lesions are typically located on exposed skin not covered by clothes, sheets or blankets, and may be arranged in linear lines or clusters, composed of 3–5 bites (also termed "breakfast, lunch, and dinner"). Bullous eruptions have not frequently been reported,5-9 but may be more common than previously assumed. Lesion development is mainly triggered by the parasite's salivary proteins, and specific IgE antibodies were demonstrated in some cases following repeated contact.4 Other complications include secondary bacterial infections, psychological sequelae and in few cases asthmatic reactions, anaphylaxis and anemia.2, 10 Currently, there is no evidence that bed bugs transmit disease-causing pathogens to humans. Reactions to bed bug bites are self-limited and resolve after several days. In severe and extensive cases topical corticosteroids and/or antihistamines alleviate the symptoms. Successful eradication of infestations remains challenging and often requires professional exterminators. All bug life cycle stages are sensitive to temperature and can be reliably killed by dry heat or steam (e.g., by washing clothes and textiles at ≥ 60°C or freezing to -20°C for ≥ 2 hours, steaming of mattresses and furniture).1, 2, 4, 10 Whole-room treatments require heating to 55–60°C for several hours.1, 2 The use of chemical insecticides to eradicate bed bug infestations harbors several disadvantages, as the aerosolized particles in insect foggers may not sufficiently reach the insects in their hidings to kill them, the compounds may pose a health risk to humans, and emerging and increasing resistances of bed bug populations to conventional insecticides have been reported in many countries, thus, limiting their use.1, 3 This case exemplifies an extensive manifestation of a cutaneous reaction to bed bug bites and the pitfalls in diagnosis. Given the reported global resurgence1, 2 and the recent increasing alleged sightings of bed bugs in certain metropolitan areas in Europe,11-13 awareness of this differential is warranted. The authors thank Andreas Ebner for excellent technical support. None.