Abstract
Irritant and allergic contact dermatitis usually presents as an eczematous process, clinically characterized by polymorphic lesions that vary according to the clinical phase, acute, subacute or chronic. Besides classic eczematous forms, however, different noneczematous clinical variants are possible. Of all the noneczematous variants, erythema multiforme-like contact dermatitis is the most common. Prevalently caused by woods, plants, and medicaments, the eruption presents with target-like, erythemato-vesicular, or urticarial lesions that may also extend to the whole cutaneous surface. The most frequent causative agents of purpuric contact dermatitis are rubber, textiles, plants and others. The eruption presents with palpable purpuric elements that evolve slowly and are followed by a variably intense and persistent pigmentation. The histopathology shows the signs of leukocytoclastic vasculitis with erytrocytes extravasation. Lichenoid contact dermatitis is an uncommon form that presents with clinical features resembling those of lichen planus: papulous lesions featuring a peculiar lilac-red hue. Lyphomatoid contact dermatitis can be defined as a benign pseudolymphomatous allergic contact dermatitis with clinical and histological features suggestive of cutaneous T cell lymphoma. It manifests with clinical features of plaque parapsoriasis. Pigmented contact dermatitis is usually observed in dark phototypes with skin hyperpigmentation due to contact with azoic dyes. Chemical leukoderma, often clinically mimicking idiopathic vitiligo, is an acquired form of cutaneous pigment loss caused by exposure to a variety of melanocytotoxic chemicals. Dyshidrosiform contact dermatitis can be primitive (expression of systemic contact dermatitis) or secondary (a contact sensitivity which complicates a preexisting palmoplantar pompholyx). Rare forms of noneczematous contact dermatitis are also pustular contact dermatitis and some nodular reactions.KeywordsNoneczematous contact dermatitisErythema multiforme-like contact dermatitisPurpuric contact dermatitisLichenoid contact dermatitisLyphomatoid contact dermatitisPigmented contact dermatitisChemical leukodermaDyshidrosiform contact dermatitis
Highlights
Irritant or allergic contact dermatitis usually presents as an eczematous process, clinically characterized by erythematoedematovesicous lesions with intense itching in the acute phase
The most represented forms of noneczematous contact dermatitis include the erythema multiforme-like, the purpuric, the lichenoid, and the pigmented kinds. These clinical entities must obviously be discerned from the corresponding “pure” dermatitis, which are not associated with contact with exogenous agents
Allergic contact dermatitis (ACD) is a common cutaneous eczematous disorder caused by contact with a range of environmental substances
Summary
Allergic contact dermatitis (ACD) is a common cutaneous eczematous disorder caused by contact (either direct or aeromediated) with a range of environmental substances. Besides the classic eczematous form, different noneczematous clinical variants are possible [1, 4–6]. The causes for such variability in ACD clinical aspects are many (Table 1). According to our data (unpublished), considering >30.000 patch tested individuals for contact dermatitis, noneczematous forms are slightly more common (52%) than the classic eczematous one (48%). Various clinical patterns of noneczematous ACD have been described: some are linked to topical use of specific haptens and others more often dependent on allergens systemic administration (Table 2).
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