The patient in this case exhibited many factors suggestive of bullous pemphigoid. Her advanced age; the clinical appearance of the skin lesions; and the subacute onset of an intensely pruritic, nonpainful rash were consistent with the diagnosis of bullous pemphigoid. A skin biopsy sample sent for routine histologic, direct immunofluorescence, and indirect immunofluorescence studies confirmed the diagnosis. Histopathologic examination of a subepidermal blister demonstrated an eosinophil-rich inflammatory infiltrate in the dermis (Figure 3). Viral and bacterial culture swabs from the blister fluid were negative, which excluded an infectious process (eg, herpes zoster).
Bullous pemphigoid is the most common blistering autoimmune disorder in the Western world, with an estimated incidence of 6-7 cases per 1 million persons in France and Germany, and an unknown incidence in the United States. It is a relatively benign condition that tends to run a waxing and waning course, with recurrent episodes of remission and relapse. It most commonly affects elderly persons but can also rarely occur in younger patients and infants.[1,2,3]
In cases of bullous pemphigoid, immunoglobulin G autoantibodies attack the skin basement membrane zone, which induces an inflammatory response and activates the complement system. The two main antigenic targets that have been identified are bullous pemphigoid antigen 1 (a 230-kd protein) and bullous pemphigoid antigen 2 (a 180-kd protein). They are both components of the hemidesmosome and allow linkage of intermediate filaments to the basement membrane.
Of these antigens, bullous pemphigoid antigen 2 is thought to be the major contributor to the pathophysiology of bullous pemphigoid. Animal studies have shown that blistering does not occur with antibodies induced solely against bullous pemphigoid antigen 1. In these cases, eosinophils are characteristically found on skin histopathologic studies. They migrate to the area of injury by the activity of eotaxin, an eosinophil-specific chemokine.
Interleukin-16 is another cytokine that has been found in high concentrations in the serum of patients with bullous pemphigoid. Interleukin-16 stimulates CD-4 helper cells and upregulates interleukin-2 receptors.
Bullous pemphigoid can present acutely or subacutely with tense, round or oval blisters and vesicles. Intensely itchy urticarial lesions can precede the bullae by days, weeks, or even months. The lesions of bullous pemphigoid may be either localized or generalized throughout the body, and they often affect the flexor areas of the limbs, as well as the abdomen, chest, and medial thighs. Mucous membrane involvement may occur, but it is uncommon. The lesions heal without any scarring.[1,2]
Although more commonly seen in pemphigus, the Nikolsky sign is also occasionally seen in cases of pemphigoid. The Nikolsky sign is the separation of superficial skin from the deeper dermis with application of gentle pressure.
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Cite this: Tuyyab Hassan. An 84-Year-Old With a Blistering Rash That Is Spreading - Medscape - Jun 28, 2016.