A pattern of subacute, chronic dermatitis or acute dermatitis may be seen. Allergic contact dermatitisĪllergic contact dermatitis occurs when there is sensitisation to a usually tolerated environmental contact such as nickel, fragrance, hair dye or preservatives. Figure 6 shows a more acute and severe example with full-thickness necrosis. Figure 5 shows an early lesion with infiltration of the epidermis by neutrophils. Irritant contact dermatitis is provoked by contact with water, detergents and other chemicals and subsequently occurs most commonly on the hands, The histology of irritant contact dermatitis is typically mild spongiosis, epidermal cell necrosis, and neutrophilic infiltration of the epidermis. The follicular pattern is found with increased frequency in more deeply pigmented cutaneous phototypes. Interestingly, a follicular pattern is not uncommon which shows spongiosis of the infundibular portion of follicles and a sparse dermal infiltrate (figure 4, arrow shows follicular spongiosis). Although acute and subacute spongiotic patterns have been described in atopic dermatitis, these are far less common than chronic spongiosis. Fibrosis of the papillary dermis may be present (figure 3).Ītopic dermatitis is a common skin condition, particularly in children and is associated with personal and family history of atopy. There is significant epidermal acanthosis, which may show a psoriasiform pattern with hyperkeratosis, hypergranulosis and minimal parakeratosis. In chronic spongiotic dermatitis, the degree of spongiosis is often mild and difficult to appreciate. A superficial dermal perivascular lymphohistiocytic inflammatory infiltrate, swelling of endothelial cells, and papillary dermal oedema are present (figure 2). Irregular acanthosis and parakeratosis are additional features compared with acute spongiotic dermatitis. The degree of spongiosis and exocytosis of inflammatory cells is mild to moderate. This is the most frequently encountered type of spongiotic dermatitis. In allergic/contact dermatitis, eosinophils may be prominent ( eosinophilic spongiosis). Vesicles are filled with proteinaceous fluid containing lymphocytes and histiocytes (figure 1, arrow). Although vesicles are usually intraepidermal, with sufficient vesiculation, they can become subepidermal. Acute eczemaĪcute spongiosis is typified by massive intercellular oedema of the epidermis with a widening of the intercellular spaces, disruption of desmosomes and formation of microvesicles. An eczematous disease may start at any stage and evolve into another. Histologically, there are three stages of eczema: acute, subacute, and chronic. Histologically, it is more useful to classify eczema based on chronicity. Three stages of eczemaĬlinically, eczema is grouped according to aetiology. Dermal changes include varying degrees of oedema and a superficial perivascular infiltrate with lymphocytes, histiocytes and occasional neutrophils and eosinophils. Droplets of plasma accumulate in the mounds of parakeratosis. Parakeratosis forms above areas of spongiosis, probably as a result of an acceleration in the movement of keratinocytes towards the surface. Infiltration of the epidermis with lymphocytes ( exocytosis) is common. Spongiotic dermatitis is a dynamic pathological process vesicles come and go and can be situated at different levels of the epidermis. Further accumulation of fluid leads to the formation of intraepidermal vesicles. Initially, there is a widening of intercellular spaces between keratinocytes and elongation of the intercellular bridges. The spongiotic tissue reaction pattern is characterised by intercellular oedema within the epidermis ( spongiosis). The consensus among most dermatopathologists is that the expression 'eczema' should be replaced with the term 'spongiotic dermatitis' to reflect the histopathologic changes that underlie the so-called 'eczemas'. However, 'dermatitis' means inflammation of the skin and is not synonymous with eczematous processes. The terms eczema and dermatitis are often used interchangeably to denote a polymorphic inflammatory reaction pattern involving the epidermis and dermis. Eczema is a common skin condition with multiple clinical patterns, characterised histologically by a spongiotic tissue reaction pattern.
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