Blistering Eruption in an Elderly Woman
A 72-year-old woman presents with a 3-week history of pruritic, tense blisters on her trunk and extremities. She also has several erosions on the oral mucosa. She has a history of hypertension and type 2 diabetes, managed with amlodipine and metformin. Examination shows multiple tense bullae on erythematous bases, some urticarial plaques, and oral erosions. Nikolsky sign is negative. Direct immunofluorescence (DIF) of perilesional skin shows linear deposition of IgG and C3 along the basement membrane zone. Indirect immunofluorescence on salt-split skin shows binding to the epidermal roof. ELISA for BP180 is strongly positive.
1. What is the diagnosis, and how do the immunofluorescence findings support it?
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The diagnosis is bullous pemphigoid (BP). DIF showing linear IgG and C3 along the basement membrane zone is characteristic. Salt-split skin indirect immunofluorescence with binding to the epidermal roof indicates antibodies against hemidesmosomal proteins (BP180/BP230), which are located on the epidermal side of the split. This distinguishes BP from epidermolysis bullosa acquisita (EBA) and anti-laminin-332 pemphigoid, which bind to the dermal floor. The strong positivity for BP180 ELISA further confirms the diagnosis.
2. What are the treatment options, and how would you choose between them?
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First-line treatment for BP includes topical clobetasol propionate 0.05% (30–40 g/day) for localized or moderate disease, or systemic corticosteroids (prednisone 0.5–1 mg/kg/day) for extensive disease. However, given her age and comorbidities (diabetes, hypertension), systemic steroids carry risks of hyperglycemia, hypertension, and osteoporosis. Alternative options: doxycycline (200 mg/day) with nicotinamide, or immunosuppressants like azathioprine or mycophenolate mofetil as steroid-sparing agents. Rituximab and dupilumab are emerging options for refractory cases. I would start with topical clobetasol for limited disease, but given the extent (trunk and extremities), systemic therapy is needed. I would use prednisone at 0.5 mg/kg/day with a rapid taper, combined with doxycycline or azathioprine, and monitor blood glucose closely.
3. What complications would you monitor for, and what is the prognosis?
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Complications include secondary infection of blisters, electrolyte imbalances, and adverse effects of treatment (steroid-induced diabetes, hypertension, osteoporosis, infection). BP is associated with increased mortality, especially in elderly patients with comorbidities. Prognosis is variable; many patients achieve remission within 1–2 years, but relapses are common. Regular follow-up with skin examination, blood glucose monitoring, and bone protection (calcium/vitamin D) is essential. The patient should be educated on wound care and signs of infection.