67-year-old woman presents with a chief complaint of a 1-month history of an asymptomatic blistering eruption on the lower extremities.
a. Insect Bite Reaction
b. Bullous Pemphigoid
c. Phemigus Vulgaris
d. Necrotizing Fascitis
e. Edema Bullae
(scroll down for answer)
E. Stasis dermatitis or Edema Bullae occurring on the lower extremities can produce non-inflammatory bullae, which are the result of edema, which extrudes through the epithelium. The absence of edema in the extremity rules out this diagnosis.
An insect bite reaction may occur on the leg and can be associated with a vesicle or bulla. However, the base of the lesions are almost always red, indicative of the significant inflammation which occurs with these bites. Bullous Pemphigoid is an autoimmune disease, which preferentially occurs in the elderly, where vesicles and bullae are formed, occasionally localized to the lower extremities.
Dermatitis herpetiformis is a bullous disease, which may appear on the legs. However, the lesions are typically smaller, the lesions always have a red base, and there is profound pruritus in all cases.
Pemphigus Vulgaris is a bullous disease, the lesions of which may arise from normal skin. However, in 95% of cases the oral cavity is involved and is usually the location where the lesions first occur.
1. Kuwahara RT. Blisters. Bullae secondary to edema. Am Fam Physician. Sep 2004 15;70(6):1125-6.
2. Cox NH, Lawrence CM. Bullous pemphigoid versus oedema blister. Diagnostic Problems in Dermatology. London: Mosby, 1998: 144 – 5.