Contact dermatitis
Contact dermatitis is the inflammation (-itis) of the skin (derma) in response to contact with particular substances (allergens or irritants). The impacted area of the body depends on the site of contact. Inflammation usually clears up once the substance has been removed/avoided.
Epidemiology
Estimated by the International Workshop on Contact Dermatitis and the JAMA network found that 1 in 5 or 20% of the general population suffer from allergic contact dermatitis. [1,2]
NICE guidelines found that contact dermatitis accounts for 4–7% of dermatological consultations in secondary care.
Irritant contact dermatitis is more common than allergic contact dermatitis — up to 80% of contact dermatitis is irritant.
About two-thirds of all cases of contact dermatitis involve the hands.
Contact dermatitis tends to be most common in young females, this is due to an increased level of exposure to substances in jewellery (such as nickel) and cosmetics.
Between 13-34% of all occupational diseases are skin diseases; of these diseases, 90-95% are contact dermatitis. [3]
Source: VisualDx and Skinsight
Contact Dermatitis
Redness and dryness on the inside of the knee
Source: Mind The Gap
Contact Dermatitis
Dermatitis (eczema) is seen on the stomach with redness and white patches
Pathophysiology [4]
Medical Student
Can be split into allergic contact dermatitis (triggered by allergens) and irritant contact dermatitis (triggered by irritants)
Allergic contact dermatitis
T cell-mediated, delayed-type hypersensitivity (Type 4 reaction)
Nickel sulphate is the most common contact allergen in most populations
The process of responding to the allergen is broken down into 2 stages; the first being sensitization (cell involvement as a response to initial allergen exposure) and the second being the allergic response after reexposure.
The sensitization phase includes the Langerhans cells capturing the allergens.
This triggers the innate immune process which leads to cells migrating to the local lymph nodes.
At the lymph nodes, the allergen (antigen) is processed and presented to naive, antigen-specific T cells.
The binding of the antigen-specific T cells and the antigen leads to the expansion and differentiation of these cells into memory/effector T cells.
This process can range from days to years dependent on the strength of the sensitizers.
During the process of differentiation, the sensitized T cells can migrate from cutaneous capillaries to the epidermis as the T cells can now express cutaneous homing antigens.
These antigens are presented to the sensitized T cells; causing an expansion of T cells. Thus, triggering an inflammatory reaction at the site of impact.
Irritant contact dermatitis
Nonspecific inflammatory reaction
Substances that can irritate the skin include chemicals (eg. acids, solvents etc), soaps, plants and chronic moisture (eg. urine, saliva etc).
Acute irritant contact dermatitis can damage the skin immediately and can create a burning/ stinging pain, caused by potent irritants
Chronic irritant contact dermatitis is caused by less potent irritants that require cumulative or chronic exposure, usually presenting with puritis
Patients
Allergic contact dermatitis
Cell-controlled reaction to allergic substances (allergen)
Nickel sulphate is the most common contact allergen in most populations
The process of responding to the allergen is broken down into 2 stages; the first being sensitization (cell involvement as a response to initial allergen exposure) and the second being the allergic response after reexposure.
The sensitization phase includes cells capturing the allergens.
This triggers an immune response (involving the body’s defence system) which leads to cells moving to the local lymph nodes (areas of the body that filter foreign substances)
At the lymph nodes, the allergen (antigen) is processed and presented to cells specifically used in immune reactions (T cells).
The binding of the antigen-specific T cells and the antigen leads to the mass duplication and transformation (differentiation) of these cells into cells that stay in the body for the long term and are released when reexposed to a specific allergen (memory/effector T cells).
This process can range from days to years
During the process of differentiation, the T cells can move from blood vessels to the layer beneath the skin
These antigens are presented to the T cells; causing an expansion of T cell numbers. Thus, triggering an inflammatory reaction at the site of impact.
Irritant contact dermatitis
Inflammatory reaction
Substances that can irritate the skin include chemicals (eg. acids, solvents etc), soaps, plants and chronic moisture (eg. urine, saliva etc).
Short-term irritant contact dermatitis can damage the skin immediately and can create a burning/ stinging pain, caused by stronger/more effective irritants
Long-term irritant contact dermatitis is caused by less effective/weaker irritants that require repeater or longer exposure, usually presenting with severe itchiness
Source: American Academy of Dermatology- National Library of Dermatology
Contact Dermatitis
Subtle redness and grey patches in darker skin tones
Source: DermNetNZ.org
Contact Dermatitis
Contact dermatitis caused by allergens on the arms
Causes [5]
Allergens
Cosmetics
Metals such as nickel or cobalt
Topical medicines such as topical corticosteroids
Rubber eg. latex
Textiles eg. dyes and resins
Strong glues
Some plants such as sunflowers, tulips, daffodils etc.
Irritants
Soaps and detergents
Disinfectants
Cement
Perfumes and toiletries
Powders, dust and soil
Risk factors [6]
Females are more likely to suffer from irritant dermatitis due to exposure to jewellery and fragrances
History of atopic dermatitis
Occupation with high levels of exposure to irritants
Source: DermNetNZ.org
Contact Dermatitis
Allergen causing dermatitis affecting the foot
Source: DermNetNZ.org
Contact Dermatitis
Allergic dermatitis with redness and brown plaques
Presentations [4]
Painful in irritant contact dermatitis
Erythema (redness)
Scaling skin
Swelling (oedema)
Crusting
Blistering
Itchiness
Investigations [5]
Occupational history of exposure
History of atopic dermatitis
Previous episodes of similar dermatitis
Referral to a dermatologist
Patch test
Potentially triggering substances are attached to an area of the body using tape
Can be attached to places like the upper arm, the back or the forearm.
2 days later, the patches are removed and assessed to note any reactions.
Can be accessed 2 days post initial investigation as atopic dermatitis reactions can appear later.
Differential diagnosis [6]
Erythema multiforme (an allergic reaction to medicine/infection)
Uriticarial (relating to itchiness) papular plaques (pattern of plaque formation)
Lichen planus (itchy rash)
Pemphigoid (blistering, and itchiness)
Granulomatous (cell pattern that appears after cell injury)
Purpuric petechial reactions (purple, small non raised patches)
Source: American College of Allergy, Asthma & Immunology
Contact Dermatitis
Brown plaque formed with follicular lesions due to nickel contact dermatitis
Source: DermNetNZ.org
Contact Dermatitis
Contact dermatitis of the arms with a border and redness
Management [4]
Students
Avoid contact with the irritant or allergen
Topical treatment includes cool compresses (saline or Burow solution) and corticosteroids.
Patients with mild to moderate acute contact dermatitis are given mid- to high-potency topical corticosteroid
Triamcinolone
Betamethasone valerate cream
Oral corticosteroids can be used for severe blistering or long-term presentation
Prednisolone
Systemic antihistamines
Hydroxyzine
Diphenhydramine help relieve pruritus
Wet-to-dry dressings can elevate oozing blisters. Can also dry skin and aid the healing process.
Patients
Avoid contact with the irritant or allergen
Cool compress, which can be applied to the skin and steroids (to reduce inflammation).
Patients with mild to moderate short-term contact dermatitis are given mid-high effective steroids that can be applied to the skin
Triamcinolone
Betamethasone valerate cream
Oral steroids can be used for severe blistering or long-term presentations
Prednisolone
Antihistamines that treat itchiness, and other allergic symptoms
Hydroxyzine
Diphenhydramine to help relieve itchiness
Wet-to-dry dressings (dressing used to remove dead skin from a wound by wetting the dressing, placing on affected skin and drying. Then removing the dressing which removes the dead skin). This can alleviate oozing blisters. Can also dry skin and aid the healing process.
Source: Mind The Gap
Contact Dermatitis
White and grey plaques/ patches on the skin
Complications
Post- inflammatory hyperpigmentation
Bacterial infection from broken skin due to dermatitis (staphylococcus or streptococcus bacteria)
Impetigo [7,8]
Myths behind Contact dermatitis [9]
Direct contact is necessary for contact dermatitis
Soft, 100% cotton is the ideal fabric to wear for contact dermatitis
Gloves protect you against all allergens
Questions you may want to ask your doctor
How can I find out what is causing my condition?
How can I protect myself against allergens/ irritants?
What can I do to prevent complications of contact dermatitis?
Is contact dermatitis infectious?
Support
British Association of Dermatologists
British Skin Foundation
Changing Faces Charity
Bibliography
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3276771/
[2] https://jamanetwork.com/journals/jamadermatology/fullarticle/2775575#:~:text=Allergic
[3] https://cks.nice.org.uk/topics/dermatitis-contact/background-information/prevalence/
[5] https://www.nhs.uk/conditions/contact-dermatitis/causes/
[6] https://www.ncbi.nlm.nih.gov/books/NBK459230/#:~:text=Risk
[7] https://ada.com/conditions/contact-dermatitis/
[8] https://www.verywellhealth.com/contact-dermatitis-symptoms-4685650
