Chapter 183. Overview of Bullous Diseases

A 100-year-old black woman with diabetes was brought to the office by her family concerned about the large blister on her leg that started earlier that day (Figure 183-1). This large bulla appeared spontaneously without trauma and there was no surrounding erythema. The bulla contained clear fluid and there were no signs of infection. The bulla was drained with a sterile needle and no further bullae developed. The diagnosis is bullosis diabeticorum, a benign self-limited condition.

Bullae are fluid-filled lesions on the skin that are larger than 5 mm in diameter. Bullous diseases are defined by the presence of bullae and vesicles (less than 5 mm in diameter). Bullous diseases are caused by many factors, including infections, bites, drug reactions, inflammatory conditions, and genetic and autoimmune diseases.

The approach to a patient with a blistering disorder begins with a complete history and physical examination. To make the final diagnosis, laboratory investigations or tissue biopsies may be needed.

History

• How did the eruption present?
• Has it changed in morphology or location?
• Has it responded to any therapies?
• Are there any associated symptoms or aggravating factors?
• How has it impacted the patient's life?
• Does the patient have any chronic medical conditions?
• Does the patient take any medications?
• Does the patient have any significant family history?

Physical Examination

• Note the location of the eruption.
• Are the bullae flaccid or tense (Figure 183-2)?
• Are there other lesions present (erosions, excoriations, papules, wheals)?
• Is Nikolsky sign positive or negative? (Does the skin shear off when lateral pressure is applied to unblistered skin?)
• Is Asboe-Hansen sign positive or negative? (Figure 183-3) (Do the bullae extend to surrounding skin when vertical pressure is applied?) Sometimes the Asboe-Hansen sign is also attributed to Nikolsky and called a Nikolsky sign, too.
• Is the Darier sign positive or negative? (Do wheals form with rubbing of the skin?)
• Note the skin background (sun-exposed skin, postinflammatory hyperpigmentation, lichenification and scarring).
• Does the patient have lymphadenopathy or hepatosplenomegaly?