[Bullous pemphigoid sparing acquired lymphedema].

Background: Bullous pemphigoid is an autoimmune disease, common in the elderly and generally of symmetrical and systemic localization. We report a case with sparing of the lower limb and acquired lymphedema secondary to lymph node surgery.

Case Report: A 74-year-old woman was hospitalized for a bullous eruption. The left lower limb was completely spared and was unaffected by pruritus. Acquired lymphedema was seen in this limb secondary to lymph node surgery. Standard histopathology tests confirmed the diagnosis of bullous pemphigoid with subepidermal blistering, while a direct immunofluorescence antibody test showed linear binding of IgG and C3 throughout the basement membrane. Western blotting revealed anti-BPAg2 antibodies. Skin biopsy on the lymphedema spared by the disease revealed no inflammatory infiltrate in the dermis. However, linear binding of anti-IgG and anti-C3 autoantibodies was observed.

Discussion: Other cases of localized bullous pemphigoid appearing on body areas treated by UV or radiotherapy have been reported. Cases of bullous pemphigoid with predilection for areas of lymphedema have also been previously described: the hypothesis has been advanced of reduced lymphatic flow, with increased antigen-antibody contact enabling better binding. Our case is original and, given the protective nature of this lymphedema, suggests two hypotheses. There could be deterioration of local cellular immunity, with decreased activation of T lymphocytes. They could also be impairment of nervous conduction, as suggested by the absence of pruritus, with partial or total inhibition of neurogenic inflammation.