**Core Concept**
Pemphigus is a group of autoimmune skin disorders characterized by the formation of intraepidermal blisters due to the breakdown of intercellular connections between keratinocytes. Intraepidermal IgG deposition refers to the presence of IgG antibodies within the epidermis, which plays a crucial role in the pathogenesis of pemphigus.

**Why the Correct Answer is Right**
In pemphigus, intraepidermal IgG deposition occurs as a result of autoantibodies targeting desmoglein proteins, which are essential for maintaining the integrity of intercellular connections between keratinocytes. These autoantibodies bind to the desmoglein proteins, leading to the disruption of cell-to-cell adhesion and the formation of intraepidermal blisters. The presence of intraepidermal IgG deposition is a hallmark of pemphigus and can be detected using immunofluorescence microscopy.

**Why Each Wrong Option is Incorrect**
**Option B:** Bullous pemphigoid is characterized by subepidermal blistering, where the blisters form below the epidermis, and is associated with the deposition of IgG and C3 along the basement membrane zone, not intraepidermally.

**Option C:** Herpes genitalis is caused by the herpes simplex virus and is characterized by the formation of vesicles or ulcers, but it is not associated with intraepidermal IgG deposition.

**Option D:** Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that can affect multiple organs, including the skin, but it is not characterized by intraepidermal IgG deposition. SLE is associated with a wide range of autoantibodies, but intraepidermal IgG deposition is not a specific feature of the disease.

**Clinical Pearl / High-Yield Fact**
Pemphigus is a classic example of an autoimmune disease where the body's immune system produces autoantibodies that target specific proteins, leading to tissue damage. Remember that intraepidermal IgG deposition is a key diagnostic feature of pemphigus, and it can be detected using immunofluorescence microscopy.

**✓ Correct Answer: A. Pemphigus**