Photoallergic dermatitis

    Clinical Features:

    • Delayed-type (type IV) hypersensitivity reaction that may develop secondary to a variety of topical agents or drugs
    • Clinically resembles allergic contact dermatitis, but the rash is confined to sun-exposed areas, as the responsible agent becomes immunogenic following exposure to light

    Histologic Features:

    • Acute to subacute spongiotic dermatitis
    • There is often a predominantly superficial dense perivascular lymphocytic infiltrate with endothelial swelling and mural edema.
    • If the causative agent is present in sufficient quantities, there may be associated phototoxic features, including:
      • Keratinocyte necrosis
      • Architectural disarray and dysmaturation
      • Hyperpigmentation with transepidermal elimination of melanin
      • Hypergranulosis
    External Links:

    Cases associated with this book:

  • Photoallergic dermatitis
    Author: Artur Zembowicz M.D. Ph.D.

    Conference: Teaching Collection