[Bullous pemphigoid sparing acquired lymphedema]

Area of Science:

• Dermatology
• Immunology
• Autoimmune Blistering Diseases

Background:

• Bullous pemphigoid (BP) is a common autoimmune blistering disease primarily affecting the elderly, typically presenting with symmetrical skin lesions.
• The standard presentation of BP involves widespread, itchy blisters, often with systemic localization.

Observation:

• A 74-year-old female presented with a bullous eruption, notably sparing her left lower limb which had acquired lymphedema post-lymph node surgery.
• Histopathology confirmed BP with subepidermal blistering and linear IgG/C3 deposition at the basement membrane zone.
• Skin biopsies from the lymphedema-affected area showed no dermal inflammatory infiltrate but did exhibit linear IgG/C3 binding.

Findings:

• The patient's lymphedematous limb was spared from the bullous eruption and pruritus.
• Western blotting identified anti-BPAg2 antibodies, consistent with BP.
• The absence of inflammation in the lymphedematous skin, despite autoantibody binding, is a key observation.

Implications:

• This case suggests that acquired lymphedema may confer a protective effect against bullous pemphigoid development or presentation.
• Potential mechanisms include local immune system alterations, such as decreased T lymphocyte activation, or impaired nerve conduction affecting neurogenic inflammation.
• Further research into the interplay between lymphedema and autoimmune skin diseases like BP is warranted to understand these protective phenomena.