What is Dermatitis?
Dermatitis is very common in the community. It is sometimes called eczema. It is the skin inflammation resulting in red itchy rash, swelling, scabbing, scaling, crusting, oozing and sores.
Acute dermatitis is a new rapidly evolving red rash on the skin which may later swell, scabs or cause blister formation. Chronic dermatitis refer to longstanding skin changes which may be darker, lichenified (thickened up) or excoriated.
There are different types of dermatitis with different clinical presentation and in some different parts of the body skin. The types of dermatitis include Atopic Dermatitis (Eczema), Allergic Contact Dermatitis, Irritant Contact Dermatitis, DiscoidEczema, Exfoliative Dermatitis, Perioral dermatitis, Seborrhoeic Dermatitis and Stasis Eczema. We will discuss the different types of dermatitis in details. Atopic dermatitis will be discussed in the next page.
What is allergic contact dermatitis?
Allergic contact dermatitis is itchy skin reaction that is caused by delayed Type IV T cell mediated hypersensitivity allergic reaction resulting from contact of specific allergen to the skin. It differs from irritant contact dermatitis caused by excessive contact with irritants without hypersensitivity reaction. The person can be sensitized after one exposure to the allergen or after several exposures to the allergen.
There are about 3000 or more allergens that can cause allergic contact dermatitis. The allergens include nickel, dyes, fragrances, preservative chemicals, poison ivy, neomycin, plants, latex gloves and photosensitivity allergy.
In USA, the prevalence of contact dermatitis is about 13.6 cases per 1000 population. Women tend to develop allergic contact dermatitis especially to nickel compared to men. There is no race predisposition.
What causes allergic contact dermatitis?
The allergens after contact with the skin induce a delayed hypersensitivity reaction. The allergen molecules then bind to the Langerhans cells which are antigen presenting cells. Langerhans cells then interact with the CD4 T helper cells and result in increased cytokine leading to inflammatory cascade. There are memory T cells that will “remember” the allergen such that upon next exposure to the allergen, patient may develop a rash within 4-24 hours. In some others they may not develop rash until few days later.
Patients may have chronic persistent relapsing dermatitis unless they find out the allergen and avoids it.
Clinical presentation of allergic contact dermatitis
The affected skin area is usually confined to the area in contact with the allergen. In very serious cases the rash may spread to other parts of the skin. For example, a nickel allergic person may develop rash over the wrist after wearing a nickel containing watch or a latex allergic person may develop hand rash after wearing latex gloves.
The affected skin will develop itch red rash that can be papules, vesicles or blisters. In long standing condition, the skin rash may become lichenified (thickened) plaques.
In some patients, chronic exposure may lead to areas of hypo-pigmented (light colored) or hyper-pigmented (darker colored) areas. The allergic contact dermatitis area may also get infected and cause secondary bacterial infection that can be treated with systemic antibiotics.
Diagnostic workup for Allergic Contact Dermatitis
The site of the rash and the chemicals/allergen that a patient has contacted with will give a clue on which allergen could be the causative agent.
1.Fungal culture with potassium hydroxide preparation may be used to exclude fungal infection as a differential diagnosis.
2.Patch testing: It is the most cost effective way to identify external chemicals that the patient is allergic to. Small amounts of the chemicals/allergen is applied onto the patient’s skin on a patch and left on for 48 hours before the patch is removed and identify which chemical trigger a skin rash. The result is read again at 72 hours and 1 week.
3.Repeat Open Application Test (ROAT): if a patient has a weak reaction of 1+ to a chemical/ allergen, then repeated application of the chemical/allergen (ROAT) can be done, if dermatitis occur few days after repeated application then the weak patch test result is relevant.
4. Dimethylgloxime Test: It is a useful practical test to identify metallic allergens such as nickel.
5.Skin Biopsy: It may be performed to exclude other differential diagnosis of the rash such as psoriasis, cutaneous lymphoma and Tinea.
Treatment of allergic contact dermatitis
The definitive treatment is to identify the allergen and remove causative agent to avoid developing chronic and relapsing dermatitis. Cool wet compresses can be applied over the rash areas.
1.Topical Corticosteroids: is the mainstay of treatment. Depending on the severity, there are different strength steroids that can be used. Long term usage of very potent topical steroids may cause skin atrophy and sometimes systemic adverse effects. When used around the eye areas, long term usage increases the risk of glaucoma, cataract and corneal thinning.
2.Emmolients: moisturizers are useful in chronic cases
3.Oral antihistamines: Antihistamines can be used to reduce itch in patients.
4.Topical immunomodulators: Topical tacrolimus and pimecrolimus creams have a better safety profile than topical steroids. It does not cause glaucoma, cataract and skin atrophy when used around the eye areas.
5: Phototherapy: Narrow band UVB or Psolaren plus ultraviolet A (PUVA) can be used for those patients who do not respond to topical steroids.
6.Immunosupressive drugs: Drugs that suppress immune system like azathioprine, cyclosporine and mycophenolate can be used to treat those patients with very severe recalcitrant widespread contact dermatitis. However they are rarely used.
7.Disulfiram: in patients with nickel allergy, the chelating effect of disulfiram may be useful.
What is Irritant Contact Dermatitis?
Irritant contact dermatitis is a form of contact dermatitis caused by contact with either physical or chemical irritants resulting inflammation of the skin. It is also a common occupational skin disorder when patients contact cleansers/ solvents/ chemicals/ adhesives/ acids/ alkalis at work. Almost anything can be an irritant if it is exposed for a longer duration and at a higher concentration.
Environmental factors like dry air, increase temperature and water may enhance the irritants effects. Hands are common affected sites as the contact with the irritants is highest here.
What causes Irritant Contact Dermatitis?
In irritant contact dermatitis, the skin reacts to the irritant and develops a cascade of inflammatory process via the release of cytokines. The severity depends on the amount of irritant exposed, the duration of contact, the pre-existing skin condition (people with underlying eczema will get more severe dermatitis) and as well as environmental factors (e.g. temperature and humidity).
Continuous exposure of water will result in maceration of skin and desiccation of skin as a result of evaporation and make the condition worse. Mechanical trauma resulting from repeated rubbing/ scratching will result in callus and lichenification formation.
Clinical presentation of Irritant Contact Dermatitis
Patients often present with a well demarcated area of red itchy macules, vesicles, blisters, fissures, scaling and hyperkeratosis (abnormal thickening of skin). The epidermis may appear parched, scalded or glazed.
Complications of irritant contact dermatitis include secondary bacterial infection, scarring, post inflammation hyper-pigmented or hypo-pigmented areas.
Diagnostic tests of Irritant Contact Dermatitis
There is no definite diagnostic test to diagnose irritant contact dermatitis. Diagnosis is made usually by excluding other skin conditions, detailed history of contact with any irritants and the clinical picture.
Patch test is not useful in irritant contact dermatitis. It is only useful in allergic contact dermatitis to identify the allergen. Fungal and bacterial culture can be done to exclude infective cause of the rash. Skin biopsy can be done to exclude other skin conditions.
Treatment of Irritant Contact Dermatitis
Definitive treatment is to identify the irritant and avoid future contact with it. Patients should use mild cleansers for washing to reduce the irritation to the skin. Emollient creams can be used to restore the epidermal barrier of the skin.
Topical steroids and immunomodulators are of unproven use in irritant contact dermatitis. Topical steroids may cause skin atrophy, corneal thinning, cataract and glaucoma when used around the eyes area. Immunomodulators may itself be an irritant to the skin.
What is Exfoliative Dermatitis?
Exfoliative Dermatitis is also called erythroderma which is a scaly, red generalized rash involving most parts of the skin. As the skin will be scaly red throughout it is also sometimes called the “red man Syndrome”.
What causes Exfoliative Dermatitis?
40% are due to pre-existing conditions (eczema, psoriasis, cutaneous T cell lymphoma & Pityriasis Rubra Pilaris), 40% is due to systemic diseases (cancers, host vs. graft reaction & HIV infection), 10% is drug induced reactions and the rest are idiopathic cases (unknown cause).
Clinical presentation of Exfoliative Dermatitis
Patients who have secondary bacterial infection may be having fever, chills, raised heart beat (tachycardia), swollen lymph nodes and electrolyte imbalance. They will first present with a generalized red itchy rash and swelling usually involving >90% of skin surface. There may be serous fluid oozing from the skin. The scaling usually starts 2-6 days after the rash.
There may also be keratoderma (skin thickening) at the hands and soles of feet. Chronic long standing Exfoliative dermatitis may lead to permanent skin pigmentation changes.
Diagnostic tests of Exfoliative Dermatitis
1.Labarotory tests: Full blood count, serum albumin, liver function test, renal function test, ESR and CRP levels can be done depending on clinical suspicion of the primary cause of the condition.
2.Imaging studies: Depend on the primary cause of the condition, imaging studies may be necessary.
3.Biopsy: Skin and lymph node biopsy may be performed to allow for histological diagnosis of the cause.
Treatment of Exfoliative Dermatitis
Exfoliative Dermatitis is a serious disease whereby patients need to be hospitalized to be monitored and treated to balance their fluid, electrolytes, maintain their body temperature and circulatory status.
The causative agent/drug should be removed. Patient should be hydrated, body temperature should be sustained and antibiotics should be given if there are signs of infection. Wet wraps, emollients may provide temporary reliefs. Oral antihistamines can be given to relief itch. Steroids and immunosuppressant can be used as interfere with the immune process that cause inflammation depending on the cause of the Exfoliative dermatitis.
What is Perioral Dermatitis?
Perioral dermatitis is a common skin disorder around the mouth area presenting as long standing papules, pustules, eczematous skin dermatitis. They are more common in women and can occur in children too.
What causes Perioral Dermatitis?
The exact etiology is unknown. Application of certain steroids and skincare creams/cosmetics may trigger perioral dermatitis.
Clinical Presentation of Perioral Dermatitis
Patients usually present with groups of red itchy papules, pustules and vesicles around the mouth area. The rash will spare the area bordering around the lips which appears pale in comparison with the rash. The rash may also occur near the nasal-mouth area (nasolabial folds) and around the eyes (periorbital).
Diagnosis of Perioral Dermatitis
Diagnosis is usually clinical and no laboratory tests are required. Differential diagnosis includes acne and rosacea.
Treatment of Perioral Dermatitis
Stop any offending topical steroids/skincare/cosmetics that trigger perioral dermatitis.
Topical antibiotics like erythromycin/metronidazole may be helpful. Topical immunomodulators like pimecrolimus may also be useful especially in those steroid induced rash.
In more severe cases, oral antibiotics as per treatment for rosacea like doxycycline, tetracycline and minocycline can be used. In those cases which do not respond, oral isotretinoin (retinoids) can be given but follow up tests should be done due to its side effects (raised liver enzymes, teratogenic and raise cholesterol levels).
What is Seborrhoeic Dermatitis?
Seborrhoeic Dermatitis is a common papulosquamous (scaly red) skin disorder which can affect the scalp, face and the trunk which are sebum (oil) rich areas. Dandruff is a milder form of Seborrhoeic dermatitis and appears as scaly patches on the scalp.
The prevalence of Seborrhoeic dermatitis is about 3-5% whereas for dandruff is about 15-20%.
What causes Seborrhoeic Dermatitis?
Seborrhoeic Dermatitis is believed to be caused by an inflammatory process with over proliferation of a normal skin yeast inhabitant Malassezia (Pityrosporum Ovale). Malassezia species has lipase activities which release inflammatory fatty acids which activates the inflammatory cascade.
Aggravating factors of Seborrhoeic dermatitis include changes in temperature/humidity, illnesses, stress, fatigue, alcohol and mechanical trauma.
Patients with certain medical conditions like Parkinson and HIV may be more prone to Seborrhoeic dermatitis.
Diagnosis of Seborrhoeic Dermatitis
Diagnosis of Seborrhoeic dermatitis is often clinical based on the history of presentation, characteristic and distribution of the rash.
Skin biopsy and fungal culture can be done to rule out other differential diagnoses for the rash.
Treatment of Seborrhoeic Dermatitis
1.Scalp involvement (dandruff)
-Shampoos containing selenium sulfide, ketoconazole, ciclopirox, zinc, coal tar, salicylic acid can be used twice weekly. Selenium sulfide, ketoconazole and ciclopirox shampoos reduce the Malassezia yeast.
-steroid scalp lotion can be used when necessary to reduce scalp itch.
-overnight occlusion with coal tar or bath oil may soften thick scalp plaques.
-Antifungal creams like ketoconazole/ciclopirox can be applied once daily for a few weeks.
-Steroidal creams like hydrocortisone can be used twice daily but may cause dependence and rebound effect when application is stopped.
-Calcineurin creams like pimecrolimus/tacrolimus creams can also be used
-Antibiotic cream like 1% metronidazole is also found to be useful.
In severe conditions, oral antifungals like ketoconazole/fluconazole and a course of antibiotics may be useful.
What is Stasis Dermatitis/Eczema?
Venous stasis eczema is a common inflammatory skin rash that occurs in the lower limbs of the middle aged/elderly (usually those > 50 years old). It is the earliest consequence of chronic venous insufficiency (varicose veins). It is also sometimes called “gravitational eczema”.
Complications of varicose veins include infection, non-healing venous ulcers, hyper-pigmentation skin changes, lichenification (skin thickening) and lipodermatosclerosis (underlying fat necrosis).
What causes Stasis Dermatitis?
Stasis Eczema is a result of chronic venous insufficiency. In venous insufficiency have a faulty 1 way valve system in the deep venous plexus of the legs. This results in backflow of the blood from the deep to the superficial venous system and also leading to venous hypertension. Acquired venous insufficiency can be due to thrombosis (blood clot in deep venous system), surgery and trauma.
Venous hypertension leads cutaneous inflammation of the lower limbs leading to stasis dermatitis.
Clinical presentation of Stasis Dermatitis
The medial aspect of the ankle is the commonest site of stasis dermatitis. There will be itchy, scaly, red, eczematous rash around the ankle which may extend upwards towards the knee. The skin may also be discolored to reddish brown color. Around the ankle and foot area there will also be localized edema (accumulation of fluid and swelling).
Chronic cases of venous insufficiency will have extensive varicose veins over the lower limbs with areas of hyper-pigmentation or atrophic patches. Chronic scratching may lead to lichenification (skin thickening). Non healing venous ulcers more commonly occur on the medial aspect of the ankle area.
Diagnostic tests for Stasis Dermatitis
1.Coagulation study laboratory tests to rule out thrombosis cause of venous insufficiency.
2.Doppler studies to examine the dynamics and patency of the venous
system and also to rule out deep vein thrombosis.
3.Skin biopsy is seldom done unless to rule out any cancerous cause for the chronic ulcer/skin plaque.
Treatment of Stasis Dermatitis
The mainstay treatment is to manage underlying venous insufficiency. Compression therapy and leg elevation will improve venous insufficiency. Severe varicose veins can be treated by sclerotherapy, ligation of the vessels and more extensive surgery by a vascular surgeon.
Oozy patches of skin can be wrapped with dressing soaked in potassium permanganate/aluminum acetate. Topical emollients are important to maximize epidermal moisture. Topical steroid creams can reduce localized inflammation and itch. Non- steroidal calcineurin inhibitors like tacrolimus/pimecrolimus may also be useful. It does not cause skin atrophy and tachyphylaxis (decrease in response after chronic usage) like steroids.
Chronic venous ulcers may require frequent dressing and wound care by a specialized wound care nurse.
Oral antihistamine can be given to reduce the itch. Oral antibiotics may be necessary in cases of skin infection.