Definition

Dermatitis, or eczema, is a superficial inflammatory disorder of the skin that can manifest as an acute, subacute or chronic disorder. Depending on the aetiology of the condition, dermatitis can be classified as either endogenous or exogenous. Endogenous forms include atopic, seborrhoeic, nummular and stasis dermatitis, while exogenous forms include contact and infective dermatitis.

Epidemiology

Atopic dermatitis affects between ten and twelve per cent of the population, occurring predominantly in children less than 5 years of age.¹ Contact dermatitis affects between 1.5 and 14 per cent of the population and can develop at any age.² Infective dermatitis can also occur at any age, while nummular and stasis dermatitis are most likely to occur in middle-aged people and elderly women, respectively.³

Aetiology and pathophysiology

There are many factors that contribute to the pathogenesis of dermatitis. The range of exogenous factors include, but are not limited to, chemicals, cosmetics, detergents, dyes, latex, metal compounds, mineral oils, plants, synthetic fibres, wool, topical drugs, and bacterial or fungal pathogens.³ Exposure to these agents can produce physiological effects ranging from skin damage and irritation (irritant contact dermatitis) to hypersensitivity reactions (allergic contact dermatitis), depending on individual susceptibility, concentration of the agent and duration of exposure.⁴

Myriad endogenous factors can also facilitate the development of dermatitis, including immunological abnormalities, such as a family history of atopic disease, environmental elements, such as food allergies, and psychoemotional influences, such as stress.⁴ Patients with endogenous dermatitis may also demonstrate diminished skin itch threshold, reduced ceramide content of the stratum corneum, decreased antimicrobial peptide production of keratinocytes, intestinal Candida overgrowth, increased proinflammatory cytokine production and intestinal dysbiosis.¹ For contact dermatitis, an individual’s susceptibility to the condition may be increased through excessive water exposure, heat, sweating, low humidity and mechanical stress, such as repeated hand washing.²

Clinical manifestations

The three key manifestations of dermatitis, including erythema, heat and pruritus, are attributed to the underlying inflammatory process of the condition. These symptoms are common across all subtypes of dermatitis, although there are some distinct differences in the presentation of each subtype. Acute dermatitis, for instance, is associated with oedema, vesicle formation, pain, exudation and impaired function. Subacute dermatitis manifests as erosions, scaling, crusting and exfoliation, whereas chronic dermatitis appears as scaling, dryness, thickening and hardening of the skin.⁵ As well as the physical manifestations, dermatitis is also associated with a decline in health-related quality of life due to irritability, sleep disturbance and negative self-esteem and self-image.⁶

The clinical presentation of atopic eczema is somewhat more defined than the subtypes. According to Ring’s criteria, a diagnosis of atopic eczema may be made if four of the following criteria are present: pruritus, family history of atopy, IgE-mediated sensitisation, stigmata of atopic eczema, age-specific distribution of skin lesions and age-specific morphology.⁷