Question of the Day

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USMLE Step 2 Question of the Day

September 28, 2022

A 62-year-old male presents to his primary care physician complaining of a recent eruption of blisters all over his body. On exam, the patient has multiple tense bullae in his axillae, groin, and in flexural areas of his arms. His oral exam reveals pink mucosa with no lesions. The physician takes a punch biopsy at the site of one of the blisters, which demonstrates deposits of IgG and complement along the basement membrane of the epidermis. This patient’s symptoms likely represent an autoimmune reaction targeting which of the following structures?

Correct Answer: 

C. Hemidesmosome

Explanation:

This patient has bullous pemphigoid, an autoimmune blistering disorder. In this disease, autoantibodies are formed against basement membrane hemidesmosome proteins. The hemidesmosome is a specialized structure that anchors cells to the extracellular matrix; in the skin, hemidesmosomes attach keratinocytes to the basement membrane. The destruction of hemidesmosomes in bullous pemphigoid results in the formation of subepidermal blisters or “tense bullae” as opposed to the flaccid bullae seen with pemphigus vulgaris. On punch biopsy, a characteristic deposition of IgG and complement can be seen along the basement membrane.

Quick Concepts:

  • Bullous pemphigoid
    • Autoimmune blistering disorder
    • Destruction of hemidesmosomes
    • “Tense bullae” on appearance
    • IgG and complement deposition on punch biopsy

Summary:

In bullous pemphigoid, an autoimmune blistering disorder, autoantibodies are formed against basement membrane hemidesmosome proteins. The destruction of hemidesmosomes in bullous pemphigoid results in the formation of subepidermal blisters or “tense bullae” as opposed to the flaccid bullae seen with pemphigus vulgaris. On punch biopsy, a characteristic deposition of IgG and complement can be seen along the basement membrane.

Correct Answer: 

C. Hemidesmosome

Explanation:

This patient has bullous pemphigoid, an autoimmune blistering disorder. In this disease, autoantibodies are formed against basement membrane hemidesmosome proteins. The hemidesmosome is a specialized structure that anchors cells to the extracellular matrix; in the skin, hemidesmosomes attach keratinocytes to the basement membrane. The destruction of hemidesmosomes in bullous pemphigoid results in the formation of subepidermal blisters or “tense bullae” as opposed to the flaccid bullae seen with pemphigus vulgaris. On punch biopsy, a characteristic deposition of IgG and complement can be seen along the basement membrane.

Quick Concepts:

  • Bullous pemphigoid
    • Autoimmune blistering disorder
    • Destruction of hemidesmosomes
    • “Tense bullae” on appearance
    • IgG and complement deposition on punch biopsy

Summary:

In bullous pemphigoid, an autoimmune blistering disorder, autoantibodies are formed against basement membrane hemidesmosome proteins. The destruction of hemidesmosomes in bullous pemphigoid results in the formation of subepidermal blisters or “tense bullae” as opposed to the flaccid bullae seen with pemphigus vulgaris. On punch biopsy, a characteristic deposition of IgG and complement can be seen along the basement membrane.


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