Key aspects

Dermatitis has been found to affect 1 in 5 people ranging from different varieties, presenting pattern, and its most likely causes. Dermatitis can be acute or chronic or both and can be lifelong. Dermatitis may fluctuate in its severity. As a general rule, dermatitis is found and described as an erythematous (red), itchy and scaly rash. Through epidermal changes, dermatitis presents a common histopathological characteristic of having spongiosis (an abnormal accumulation of fluid in the epidermis) or intercellular oedema.

Dermatitis can present acutely (known as acute eczema) with a rapidly evolving rash that may swell, weep then crust, blister from vesicles, present with scale, and is usually erythematous-like with poor defining borders. Its chronic version can present with all the acute characteristics, but most of the time is seen as more of a present and persistent rash. The rash may be darkened or more pigmented, thickened, fissured, increased in scales, and may display lichenification due to extensive scratching.

Etiological factors

Dermatitis is a complex disease, and because it has many variants, it is difficult to pinpoint its origin. For example, atopic dermatitis occurs through complex interactions between genetics, inflammation and the environment the person is living in, such as the weather, exposure to irritant, temperature and non-specific triggers. Family history plays a huge role and is found to be 70% of the case in atopic dermatitis. It was found that up to 80% of people affected with atopic dermatitis have a dysregulated immune system where IgE (immunoglobulin E associated with allergies) is increased in the serum due to Th2 cells. Up to 50% of people have an abnormal epidermal barrier where there is a deficiency in the filaggrin protein, resulting in a skin surface that struggles to hold water and is susceptible to irritants, allergens and infections. The defensins proteins are also found to be faulty increasing infection susceptibility. The result causes the keratinocytes cells to die, spongiosis and further infiltration of inflammatory cells. Figure 1 demonstrates histologically how an acute stage of dermatitis should present with blistering and its chronic stage demonstrating the thickening of the epidermal layer due to hyperkeratosis and parakeratosis. See “different variants of dermatitis” section to see the other causes why the skin presents as dermatitis.

Aggravating factors

• Family history.

• Age and health condition.

• Cold and dry weather.

• Sand from the beach or sandpits.

• Bathing too many times may exacerbate dermatitis. Utilise lukewarm water and showers are shown to be better. Use soaps that the dermatologist recommends.

• Certain clothes may exacerbate dermatitis. Avoid coarse fibres and wear soft and smooth garments.

• Avoid any irritants such as chemicals, incontinence, dust, overexposure of water, solvents, detergents, and physical injury.

• Staphylococcus aureus or Streptococcus pyogenes infections.

• Occupation exposure.

Clinical features

As mentioned above dermatitis presents as a patchy, red (erythematous), poorly defined rash that is mostly found in the cubital fossae (the flexure between the forearm and the biceps), the popliteal fossae (behind the knees), and the face, but can be found anywhere on the body if it is severe enough. Dryness of the skin is common. Patients with dermatitis experience itching of the skin, and in some cases, the itching may be so severe that patients may scratch the top layer off which is called excoriation of the skin. Itching may accelerate the epidermal changes and thickens the top layer of the skin; this is called lichenification. Dermatitis may occur due to a bacterial infection and may present the skin as crusty or weepy. Do bear in mind that dermatitis can come in many forms and each type can present with their unique general presentation; hence a correct diagnosis is essential.

Different variants of dermatitis

Endogenous

Endogenous dermatitis is more common and is associated with genetic susceptibility.

• Atopic dermatitis: seen in children with a history of asthma or hay fever.

• Seborrhoeic dermatitis or dandruff: may be infantile or is seen in teens/adults, is mostly associated with Malassezia yeasts and inflammation.

• Nummular dermatitis: are scattered looking coins-shape rashes.

• Stasis or gravitational dermatitis: comes from poor blood flow around the lower legs.

• Asteatotic dermatitis or dry skin: cracked paving stone appearances, arises mostly on the lower legs.

• Pompholyx dermatitis: small, fluid-filled blisters appear on the palms, fingers and soles of feet.

• Otitis externae: dermatitis affecting the external ear canal.

Exogenous

Exogenous dermatitis is more due to external factors.

• Irritant contact dermatitis: can be done due to friction, liquids such as solvents and detergents. Is seen to be associated more with people who have a tendency to display atopic dermatitis.

• Allergic contact dermatitis: dermatitis caused by elements that people do not generally react to. Patch testing can be done.

• Otitis externae: dermatitis affecting the external ear canal.

Differentials and complications

Differentials

Other diseases to look for that may resemble dermatitis are:

• Psoriasis: has a well-defined border and is generally not itchy. Commonly associated with nail abnormalities. Auspitz sign is positive (where small bleeds occurs after peeling a plaque off).

• Scabies: look for tiny burrows and social history.

• Lichen planus: can appears as purplish, itchy, flat-topped bumps.

• Tinea (fungal infection): usually asymmetrical, found in humid weather, central clearance, use skin scrapping to differentiate.

• Angioedema: similar to urticaria, and is often abrupt and short swelling of the skin.

• Palmoplantar pustulosis: related to psoriasis, it is an uncommon, chronic pustular condition affecting the palms and soles.

• Erysipelas: is a bacterial infection in the upper layer of the skin. It is similar to another skin disorder known as cellulitis, which is an infection in the lower layers of the skin.

Complications

• Lichenification of the skin.

• Hyperpigmentation.

• Lipodermatosclerosis occurs, especially in stasis dermatitis.

• Ulceration.

• Infections of the skin such as impetiginisation (secondary infection causing yellow crusting).

• Cellulitis.

• Psychological distress.

Treatment

As seen in the differentials, being sure of the diagnosis is crucial in treating dermatitis, thus look at its clinical features or perform a skin biopsy for certainty. It is essential to explain to the patient that dermatitis is a lifelong/chronic disease and takes time and patience to treat. Having said that, dermatitis has a good prognosis. Referral to a specialist may be necessary. An important aspect of treatment is to identify and tackle any aggravating or contributing factors (see above).

Treating dermatitis include:

• Avoid aggravating factors and lifestyle modification.

• Use of emollient, the greasier the better (helps to avoid the dryness).

• Wet dressings over emollient to prevent further scratching

• Use of topical anti-inflammatory, corticosteroids or immunomodulators.

• Investigations of genetics and treatment of allergies.

• Pimecrolimus cream.

• Antibiotics against infections that aggravate dermatitis.

• Antihistamines.

• Other treatments such as systemic steroids, methotrexate, phototherapy.

• Exogenous dermatitis: remove the irritant from the skin and wear protective clothing.

• Psychological treatment and social support.

The severity will dictate what type of treatment should be used and type of medication combinations.

Published 20th December 2020. Last reviewed 1st December 2021.

Reference

A PPOC/CHICO Learning Community & Integration Program © 2014 Pediatric Physicians’ Organization at Children’s (PPOC). Atopic Dermatitis Didactic Webinar: Bringing Basic Dermatology Care to the Pediatric Medical Home. Thursday May 4, 2017. Accessed November 30, 2020.

Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand,1997. Dermatitis. Dermnet NZ website. https://dermnetnz.org/topics/dermatitis/. Accessed November 30, 2020.

Mayoclinic authors. Dermatitis. Mayoclinic website. https://www.mayoclinic.org/diseases-conditions/dermatitis-eczema/symptoms-causes/syc-20352380. Updated June 11, 2019. Accessed December 3, 2020.

Plastic Surgery Key Authors. Eczema and Dermatitis. Plastic Surgery Key website. https://plasticsurgerykey.com/eczema-and-dermatitis/#figureanchor7-1. Accessed November 30, 2020.