Bites, Bullous Insect Bites
Definition: Bullous insect bites are delayed hypersensitivity reactions that occur in people who are already sensitized (2). They are characterized by blisters packed with fluid that appear on the skin (1).
Etiology: The bites arise from an immune response to toxins being released at the bite site (1). The most common bites come from spiders, fleas, bed bugs and mosquitos.
Epidemiology: Bullous reactions can occur often in people with various hematological malignancies and chronic lymphocytic leukemia (2).
Signs: Plaques or erythematous papules that develop into tight, fluid filled bullae (1,2). Lesions may be encircled by erythema or edema and frequently appear at the site of an insect attack (1).
Symptoms: At the location of the blisters, patients may experience itching, burning, or pain (1,2). Scratching the blisters increases the risk of bacterial infection (1).
Differentials: Bullous pemphigoid, dermatitis herpetiformis, contact dermatitis, insect sting hypersensitivity (1,3).
Diagnosis: Diagnosis is clinical and based on the patient’s history of insect exposure and characteristics of the lesions.
Treatment: Due to the increased risk of bacterial infection, appropriate wound care is necessary using soap and water (1). Antihistamines and topical or oral corticosteroids can be used to relieve symptoms(2). The use of insect repellant and protective clothing is the best way to prevent bites.
References: (AMA)
1. B Koyani B, D Pathak R, H Thacker D. Bullous arthropod bite reaction. International Journal of Case Reports and Images. 2022;13(2):164-167. doi:10.5348/101352z01bk2022cr
- Collins P, Sepede J. Bullous arthropod bite reaction. BMJ Case Reports. 2018;11(1). doi:10.1136/bcr-2018-228079
- Kim JE, Kim S-C. Insect bite-like reaction with bullous lesions mimicking bullous pemphigoid in a patient with chronic lymphocytic leukemia. Annals of Dermatology. 2018;30(4):468. doi:10.5021/ad.2018.30.4.468