Wolf's isotopic response: a case of localized bullous pemphigoid on the herpes zoster scar

A case of Wolf's isotopic response is reported. A 68-year-old-female presented with vesicles and bullae on the scars of the left chest and the back for 2 months. Dermatological examination revealed five vesicles and bullae of various sizes on the edge of a 10 cm×5 cm scar, with a deep central ulcer sized 5 cm×5 cm, under the left armpit. Ulcer was with little discharge and dark crusts. The vesicles were with clear fluid and negative for Nikolsky's sign. Two bullae were seen on a 3 cm×2 cm hypertrophic scar at T2 to T4 of the left anterior chest. One hypertrophic scar with a bulla sized 1.5 cm and another one with 1 cm erosion and pustular secretion were on the left back. Patient had no mucosal involvement. Histology of skin lesion showed subepidermal blister and perivascular infiltrates of a few lymphohistiocytes, neutrophils and plasma cells in the superficial dermis. Direct immunofluorescence showed linear deposition of C3 in the basement membrane zone. The diagnosis was isotopic response: bullous pemphigoid secondary to herpes zoster. After the treatment with oral prednisone acetate, the blisters resolved in 2 weeks. No recurrence was observed during 15-months follow-up. The follow-up is still ongoing.