May Bacterial Infections Trigger Bullous Pemphigoid? Case Report and Review of Literature

Abstract

Bullous pemphigoid (BP) is an autoimmune blistering skin disease, mainly observed in the elderly. Infections have been suggested as possible disease triggers. However, infections may even heavily influence the disease clinical course and mortality. A 75-year-old woman was admitted to hospital for severe erythematosus blistering disease, accompanied by hyper-eosinophilia and hyper-IgE. The culture of bullous fluid was positive for Enterococcus faecalis, the blood culture was positive for Staphylococcus aureus, and the urine culture was positive for Proteus mirabilis and Escherichia coli. Moreover, circulating anti-BP180 IgG was present and the histopathological/ultrastructural examination of a lesional skin biopsy was compatible with BP. High eosinophil levels (up to 3170/µL) were found throughout the clinical course, while values below 1000/µL were associated with clinical improvement. The total IgE was 1273 IU/mL, and specific anti-G/V-penicillin/ampicillin IgE antibodies were positive. The patient had a complete clinical recovery in two months with methyl-prednisolone (40 then 20 mg/day) and low-dose azathioprine (50 mg/day) as a steroid-sparing agent. The steroid treatment was tapered until interruption during a one-year period and intravenous immunoglobulins have been administered for three years in order for azathioprine to also be interrupted. The patient stopped any treatment five years ago and, in this period, has always been in good health. In this case, the contemporaneous onset of different bacterial infections and BP is suggestive of bacterial infections acting as BP trigger(s), with allergic and autoimmune pathways contributing to the disease pathogenesis.

Keywords: IVIg; autoimmunity; bullous pemphigoid (BP); infections.

Figure 1

Blistering skin lesions on erythematous base on the right arm.

Figure 2

(A) The bullous lesion at histopathologic examination is composed of a subepidermal blister (*), with underlying sclerosis of the papillary component of the dermis, dilated capillary vessels, and perivascular chronic lymphocytic infiltrate with an eosinophilic component. A significant actinic elastosis is visible in the reticular dermis. (Hematoxylin/eosin staining; 100× magnification; bar 100 µm). (B) Transmission electron microscopy performed on the perilesional skin reveals the presence of small subepidermal blisters (*) without epidermal basal cell damage (uranyl acetate/lead citrate; bar: 5 μm). (C) Ultrastructural analysis of lesional skin shows the formation of a blister (*) between the basal keratinocytes and the partially fragmented lamina densa (arrows), which defines the floor of the blister (uranyl acetate/lead citrate; bar: 2 μm).