Chapter 29-6: Bullous Arthropod Bites

TEXTBOOK PRESENTATION

This condition commonly presents as a cluster of tense blisters on exposed skin. The blisters tend to be large (≥ 1 cm) and surrounding skin is normal.

DISEASE HIGHLIGHTS

1. Description of the lesion: large, often tense blisters on normal skin (Figure 29-7).

2. Character and location of the lesion

   1. The lesions tend to develop in exposed areas of the skin, such as the extremities.

   2. The patient will otherwise appear well.

   3. The lesions are typically extraordinarily pruritic.

   4. Although the blisters arise from otherwise normal skin, surrounding inflammatory changes from rubbing and scratching are often present.

3. Arthropod bite reactions are dermal hypersensitivity reactions to antigens from the saliva of insects.

4. Bedbugs, fleas, mosquitos and many varieties of mites are all typical culprits.

5. It is not possible to identify the culprit insect by the appearance of the bite.

EVIDENCE-BASED DIAGNOSIS

1. Diagnosis is made by clinical presentation.

2. Histopathology, though rarely necessary, can be supportive, demonstrating edema, a subepidermal blister, and a dermal inflammatory infiltrate with numerous eosinophils.

TREATMENT

1. Avoidance of future bites with use of protective clothing and insect repellants.

2. Attention to eradicating the source of the biting insects, such as on pets, nests, etc.

3. Supportive local care to prevent secondary infection and relieve pruritus.