**Core Concept**
Acantholysis is a process in which there is a breakdown or separation of keratinocytes, the main cell type of the epidermis, leading to the loss of cell-to-cell adhesion. This phenomenon is often observed in various skin disorders, including autoimmune diseases and infections. The separation of keratinocytes disrupts the normal architecture of the epidermis, resulting in a range of clinical manifestations.

**Why the Correct Answer is Right**
Acantholysis involves the disruption of desmosomes, which are specialized intercellular junctions that provide strong adhesion between adjacent keratinocytes. The loss of desmosomal adhesion leads to the separation of keratinocytes, resulting in acantholysis. This process can be mediated by various mechanisms, including the action of autoantibodies or the release of inflammatory mediators. In conditions such as pemphigus vulgaris, acantholysis is a hallmark feature, leading to the formation of intraepidermal blisters.

**Why Each Wrong Option is Incorrect**
**Option A:** Lysis of the basal cell layer is known as basal cell degeneration or basal cell damage, which is a different process from acantholysis.
**Option C:** Thickening of the granular layer is a feature of certain skin conditions, such as psoriasis, but it is not related to acantholysis.
**Option D:** Thickening of the corneum layer is a feature of conditions such as ichthyosis, but it is not associated with the separation of keratinocytes.

**Clinical Pearl / High-Yield Fact**
Acantholysis can be distinguished from spongiosis, which is an intercellular edema of the epidermis, by the presence of a loss of cell-to-cell adhesion and the formation of intraepidermal blisters.

**Correct Answer:**
✓ Correct Answer: B. Separation of keratinocytes