Systemic Contact Dermatitis

An important etiopathogenic and clinical aspect of allergic contact dermatitis is the persistence, recurrence or spread of the disease following the introduction by systemic route of the allergen or of other cross-reacting substances. This is what occurs in the systemic contact dermatitis phenomenon, a condition that arises in subjects who have undergone prior sensitization through skin contact. There are various routes of expoxure that elicit the eruption (inhalation, oral, intramuscular, intravenous, rectal, vesical, subcutaneous, and inplants within the body). Clinically, the onset of the eruption occurs rapidly, within a few hours after exposure, and manifests with skin and systemic (headache, arthralgia, fever, diarrhea, nausea, muscle ache, etc.) signs. Among the various skin symptoms, the flare-up of previous positive patch tests raise the suspicion of systemic contact dermatitis, and is a fashinating and specific sign of the eruption. Characteristic and frequently obverved are the generalized rashes (maculo-papulo-vesicular rash, erythema multiforme-like rash, purpuric and urticarioid rashes). Among the localized skin rashes, the vesicular hand eczema is common, prevalently in nickel-sensitized subjects. The baboon syndrome is a characteristic but rare eruption on the buttocks, in the genital area and a V-shaped reaction on the inner things. Various medicaments, metals, foods, plants, and other chemicals may be implicated as causative agents. Systemic contact dermatitis presents with a vast spectrum of differential diagnosis, ranging from infections to bullous diseases.