Which skin findings are helpful in evaluating a patient with blisters?

Several features of vesiculobullous lesions are important to note, including the distribution, symmetry, involvement of mucosal surfaces, and associated lesions (such as erosions, ulcers, and crusts). Additional types of skin lesions, such as urticarial lesions, should be noted. In bullous pemphigoid, urticarial lesions often precede the development of blisters. In some vesiculobullous diseases such as dermatitis herpetiformis, secondary excoriations may be the only lesions visible, with no intact blisters.

The character of the blisters also may provide useful information. Flaccid blisters may indicate a more superficial blistering process than is seen with tense blisters. However, factors other than the depth of the blister are important, including site (blisters on acral skin, which has a thick stratum corneum, are often tense even when superficial) and the specific disease process (in toxic epidermal necrolysis, the blistering is subepidermal, but vesicles and bullae are usually flaccid with large sheets of skin sloughing).