Bullous Pemphigoid in Infancy Showing Epitope-spreading Phenomenon: Recovery with Topical Therapy.

A 6-month-old Japanese boy developed quickly progressing generalised skin lesions. Vaccination was not given in previous 4 weeks. Physical examination revealed extensive annular plaques with blisters and excoriations on entire body (Fig. 1). Laboratory examinations showed increases in leucocytes (32,500/μl; normal, 3,900–9,300/μl), eosinophils (40.5%; normal, 0.2–4.1%) and C-reacting protein (1.12 mg/dl, normal < 0.3 mg/dl). The results of commercially available enzyme-linked immunosorbent assay kits (ELISAs) (MBL, Nagoya, Japan) were negative for desmogleins 1 and 3, but positive for BP180 NC16a domain (index > 1,000, normal < 9) and BP230 (index 19.64, normal < 9). Histopathology revealed subepidermal blisters and eosinophilic infiltration in both blister and upper dermis (Fig. 2a, b). Direct immunofluorescence showed linear deposits of IgG and C3 to basement membrane zone (BMZ). Indirect immunofluorescence using normal human skin revealed circulating IgG anti-BMZ autoantibodies at 1:160 (Fig. 2c), which reacted with epidermal side of 1M NaCl-split normal human skin (Fig. 2d). Immunoblotting of normal human epidermal extract detected circulating IgG autoantibodies to BP180, but not BP230. Immunoblotting also showed IgG reactivity with recombinant proteins of both NC16a and BP180-C-terminal domains of BP180. Immunoblotting of concentrated culture supernatant of HaCaT cells demonstrated IgG reactivity with LAD-1. The patient was treated only with 0.12% betamethasone valerate and 0.05% clobetasone butyrate ointments, because the parents requested not to apply systemic corticosteroids. The treatment was effective and led to remission within 3 months. For following 3 months, no recurrence was observed.