Spongiosis involves:
**Core Concept**
Spongiosis refers to the intercellular edema within the epidermis, leading to a spongy appearance under histological examination. This condition is often associated with various skin diseases, including eczema and dermatitis.
**Why the Correct Answer is Right**
Spongiosis occurs due to the disruption of the intercellular connections between keratinocytes, specifically the desmosomes and tight junctions. This disruption leads to an increase in the permeability of the epidermal barrier, resulting in the accumulation of fluid and ions between the cells. The increased fluid pressure causes the cells to separate, creating a spongy appearance.
**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect because spongiosis specifically refers to the intercellular edema, not the inflammation of the epidermis.
**Option B:**
This option is incorrect because spongiosis is not associated with the proliferation of keratinocytes.
**Option C:**
This option is incorrect because spongiosis is not a characteristic feature of psoriasis.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that spongiosis can be a diagnostic feature of various skin conditions, including eczema and dermatitis. Histological examination of a skin biopsy can help to confirm the presence of spongiosis and guide further management.
**Correct Answer: D. Inter cellular edema**