What is the underlying mechanism responsible for the development of pemphigus vulgaris?
Solution
Correct Answer: Option B
The underlying mechanism responsible for the development of pemphigus vulgaris is an autoimmune attack on desmosomal proteins, specifically desmoglein 3 and, in many cases, desmoglein 1. Desmosomes are specialized structures that facilitate cell-to-cell adhesion between keratinocytes in the epidermis.
In pemphigus vulgaris, autoantibodies (IgG) target these desmosomal cadherins, disrupting their function and leading to the loss of adhesion between keratinocytes, a process known as acantholysis. This results in the formation of flaccid intraepidermal blisters and erosions on the skin and mucous membranes.
To clarify why the other options are incorrect:
- Option 1: Autoimmune destruction of hemidesmosomes occurs in bullous pemphigoid, not pemphigus vulgaris. Hemidesmosomes anchor basal keratinocytes to the basement membrane, and their destruction leads to subepidermal blistering.
- Option 3: Type IV hypersensitivity reactions involve T-cell mediated cytotoxicity, often against intracellular antigens, but this mechanism is not central to pemphigus vulgaris.
- Option 4: Immune complex deposition in dermal blood vessels is characteristic of diseases like lichen planus or vasculitis, but not of pemphigus vulgaris.
In summary, the hallmark of pemphigus vulgaris is the autoimmune targeting of desmosomal proteins, leading to loss of keratinocyte adhesion and intraepidermal blister formation.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th Edition, Chapter on Diseases of Skin (Chapter 9, Pages 122-130)
In pemphigus vulgaris, autoantibodies (IgG) target these desmosomal cadherins, disrupting their function and leading to the loss of adhesion between keratinocytes, a process known as acantholysis. This results in the formation of flaccid intraepidermal blisters and erosions on the skin and mucous membranes.
To clarify why the other options are incorrect:
- Option 1: Autoimmune destruction of hemidesmosomes occurs in bullous pemphigoid, not pemphigus vulgaris. Hemidesmosomes anchor basal keratinocytes to the basement membrane, and their destruction leads to subepidermal blistering.
- Option 3: Type IV hypersensitivity reactions involve T-cell mediated cytotoxicity, often against intracellular antigens, but this mechanism is not central to pemphigus vulgaris.
- Option 4: Immune complex deposition in dermal blood vessels is characteristic of diseases like lichen planus or vasculitis, but not of pemphigus vulgaris.
In summary, the hallmark of pemphigus vulgaris is the autoimmune targeting of desmosomal proteins, leading to loss of keratinocyte adhesion and intraepidermal blister formation.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th Edition, Chapter on Diseases of Skin (Chapter 9, Pages 122-130)
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