Case report
A 77-year-old Japanese man was referred to us with a 1-year history of
pruritic erythema, bulla and erosion on the head/neck, trunk and
extremities (Fig. 1a). The patient had already been diagnosed with BP in
the previous clinic based on a high titer of serum anti-BP180 NC16a
domain antibodies. On the back, the erythema was found to be distributed
away from the pigmented areas corresponding to the inactive lesion (Fig.
1b). An intact zone of about 2 cm in width clearly separated active
erythematous lesions from inactive pigmented lesions. Cross-linked
enzyme aggregate assay indicated >1,000 U/ml of serum
anti-BP180 NC16a domain antibodies (normal range, <9.0 U/ml).
Histopathological examination of the erythema and bullae revealed
subepidermal blistering accompanied by eosinophilic infiltration (Fig.
2a). Direct immunofluorescence assay revealed immunoglobulin G
deposition in the basement membrane zone (Fig. 2b). Bullous pemphigoid
was diagnosed. Erythema and bullae improved after administration of
high-dose systemic corticosteroid.
We furthermore approached the phenomenon of the distribution of the
active lesion away from the inactive lesion by immunohistochemistry. We
counted CD4+, CD25+ and
FoxP3+ cells in the width of 4 mm of the tissue
obtained from active lesion, inactive lesion, and intact skin (Table 1,
Fig. 2c-2e). Compared to the intact skin, CD4+ cells
were counted 2.22-fold and 1.83-fold in active lesion and inactive
lesion, respectively. Similarly, CD25+ cells were
counted 1.48-fold and 2.33-fold. FoxP3+ cells were
counted 1.75-fold and 2.64-fold.