What are the Histological Features of Fixed Drug Eruptions?
Histologically, fixed drug eruptions are characterized by a combination of epidermal and dermal changes. The epidermis often shows necrotic keratinocytes, which are a hallmark of FDE. Additionally, there is often spongiosis, or intercellular edema, which may be accompanied by vesiculation.
In the dermis, a superficial and deep perivascular infiltrate composed predominantly of lymphocytes can be observed. There may also be the presence of eosinophils and melanophages, which are indicative of post-inflammatory pigmentation changes. The infiltrate can extend into the subcutaneous tissue, especially in more severe cases.
