Which of the following statements regarding this lesion is INCORRECT?
A) It is characterized by intercellular edema that results in impaired cohesion between epidermal keratinocytes. This finding represents a nonspecific inflammatory reaction pattern with little correlation to etiology.
B) The clinical and histological appearances vary depending on the etiology, duration, location, and superimposed secondary changes (ie, excoriation).
C) The eruption always represents a type IV hypersensitivity reaction to an exogenous antigen.
D) It is divided into acute, subacute, and chronic stages.
E) A PAS stain should be considered to exclude dermatophyte infection.
Spongiotic dermatitis is a nonspecific inflammatory reaction pattern (histopathologic diagnosis) that corresponds to the clinical eczematous dermatoses. The eczematous dermatoses differ in their pathophysiology. They can result from immune dysregulation (atopic dermatitis), delayed type IV hypersensitivity (allergic contact dermatitis), or direct epidermal injury/innate immune reaction (irritant contact dermatitis).
Common Eczematous Dermatoses
Allergic contact dermatitis
Irritant contact dermatitis
Spongiotic pigmenting purpura
The unifying microscopic feature is a sponge-like appearance of the epidermis due to intraepidermal edema with widened spaces between keratinocytes. This is the result of exocytosis of T lymphocytes into the epidermis with release of proinflammatory cytokines and induction of keratinocyte apoptosis through “killer molecules.” Keratinocyte adhesion molecules (ie, E-cadherin) are subsequently destroyed and there is accumulation of extracellular fluid in the widened intracellular spaces.
There is significant variability in the clinical and histopathologic appearance of spongiotic dermatitis depending on the duration, etiology, location, and presence of superimposed secondary changes such as excoriation. Most examples evolve through a course of acute, subacute, and chronic stages; however, not all lesions do this. Histopathologically, lesions of acute spongiotic dermatitis exhibit pronounced superficial dermal and intraepidermal edema with lymphocyte exocytosis and intraepidermal vesicles that contain clusters of Langerhans cells admixed with lymphocytes. The corresponding clinical presentation is of edematous, inflamed, oozing papules and plaques, often with visible vesicles. As the lesions evolve into subacute spongiotic dermatitis, there are varying degrees of acanthosis (hyperplasia) with foci of serum-imbued parakeratosis resulting from the transepidermal elimination of the spongiotic vesicles. This correlates clinically with the presence of scale crust. As this occurs, there is also decreased superficial dermal and intraepidermal edema. Lesions of chronic spongiotic dermatitis exhibit acanthosis, hypergranulosis, ...