Case 1: Acanthosis (more of a chronic finding), perivascular lymphocytic infiltrate and prominent numbers of eosinophils are suggestive of an allergic subacute spongiotic dermatitis.
Spongiosis can be appreciated. Note the presence of intercellular bridges. Pareakeratosis is present in abundance overlying the surface.
Eczematous dermatitis is actually a very broad term and describes a clinical impression. It can exogenous (e.g. allergic or irritant/contact dermatitis) or endogenous (e.g. nummular eczema). Spongiotic dermatitis is the histologic correlate and intraepidermal edema ("spongiosis") as the defining microscopic feature in these conditions (Sternberg).
Note that the histology will change over the course of the disease. In the acute phase, spongiosis and the presence of intraepidermal vesicles will predominant whereas in the chronic stages, there will be papillomatosis and acanthosis (Sternberg).
The allergic form of contact dermatitis will be characterized by an eosinophilic infiltrate. The nonallergic form results from exposure to irritants (e.g. soaps) and does not require prior sensitization. In both forms, there will be spongiosis.
Endogenous eczemas include nummular eczema, atopic dermatitis, dyshydrosis and seborrheic dermatitis because there is no known exogenous instigating factor.
Distinguishing between subacute spongiotic dermatitis and the patch stage of T-cell lymphoma can be problematic. One of the key distinguishing features (aside from clinical history) is that epidermotropism is seen in T-cell lymphoma whereas spongiotic dermatitis exhibits exocytosis. Epidermotropism is defined as atypical lymphocytes within the epidermis whereas exocytosis is the presence of normallymphocytes within the epidermis. If the degree of atypia in the lymphoctyes is difficult to ascertain, the presence of spongiosis would favor dermatitis (Sternberg).
Patients note itching, redness, and flaking.
→Acute spongiotic dermatitis is characterized by spongiosis and intraepidermal vesciles. As the process becomes chronic, the spongiosis decreases and there is increased papillomatosis and acanthosis.