Multiple Brownish Nodules with Blisters on the Trunk and Extremities

A 79-year-old gentleman presented with a 1-year history of many pruritic nodules on the trunk and extremities. Some blisters developed for several weeks before he visited our clinic. On physical examination, there were about 60 discrete, hyperkeratotic, brownish nodules on the trunk and four limbs (Fig. 1). Besides, there were several tense blisters right on some of the prurigo lesions and the normal skin (Fig. 2). No oral erosion or blister was found. Routine investigations including complete blood count, differential counts of white blood cells, renal function and liver function tests were all within normal limits. The biopsy specimen from the blister showed subepidermal vesicle with lymphocyte and eosinophil infiltration in the upper dermis. The other biopsy specimen from the prurigo lesion showed features of prurigo nodularis (Fig. 3). Direct immunofluorescence (DIF) studies of both the peri-blister and prurigo skin revealed linear IgG and C3 depositions at the basement membrane zone (BMZ) (Fig. 4). Indirect immunofluorescence (IIF) studies of his serum detected anti-BMZ autoantibodies. Besides, his serum autoantibodies bound to the epidermal side on salt-split normal human skin. Western blotting using human epidermal extract as substrate revealed the presence of serum autoantibodies against 230 kD antigen (BP230).