Interstitial pneumonia associated with bullous pemphigoid.

Bullous pemphigoid, the most common autoimmune blistering disease, is characterized by an autoimmune response to a component of hemidesmosomes within the dermal-epidermal junction. Immunofluorescence examination of skin biopsies demonstrates linear deposition of IgG and C3 in the basement membrane zone. A 73-year-old woman was admitted to our institution because of interstitial lung disease with persistent dry cough, dyspnea on exertion, and bullous eruptions on the skin of her trunk and extremities. Chest CT scan, BAL fluid, and transbronchial lung biopsy findings indicated a likely nonspecific interstitial pneumonia pattern. Direct immunofluorescence showed linear deposition of IgG and C3 along the basement membranes of the lung and skin specimens. Lung disorders associated with bullous pemphigoid are extremely rare, and, to our knowledge, this is the first report of an immunologically confirmed case of interstitial pneumonia.