Fast Five Quiz: Compare Your Knowledge of Contact Dermatitis

Contact dermatitis is an acute or chronic skin inflammation caused by cutaneous interaction with a chemical, biologic, or physical agent. Contact dermatitis after a single exposure or multiple exposures may be irritant or allergic. Clinically, differentiating between these processes may be difficult.

Irritant contact dermatitis is caused by direct tissue damage following a single exposure or multiple exposures to a known irritant. By contrast, in allergic contact dermatitis, tissue damage by allergic substances is mediated through immunologic mechanisms. A complete history related to exposures at home, the workplace, and in recreational activities is essential to making the diagnosis and identifying the causative agent.

Acutely, eczematous or nonspecific dermatitis is the most common clinical expression of this induced inflammation. The severity of the dermatitis ranges from a mild, short-lived condition to a severe, persistent, job-threatening, and possibly life-threatening disease. Treatment of both irritant contact dermatitis and allergic contact dermatitis begins with removal of the offending substance.

How much do you know about this condition? Test yourself with this short quiz.

Which of the following is accurate regarding the etiology of contact dermatitis?

A. Poison ivy (Toxicodendron radicans) is the leading cause of allergic contact dermatitis around the world
B. Dry air alone is insufficient to provoke irritant contact dermatitis
C. Acrylates and methacrylates have been significantly associated with contact allergy and allergic contact disease
D. Irritation associated with trauma is not considered contact dermatitis

Answer: C. Acrylates and methacrylates have been significantly associated with contact allergy and allergic contact disease

Discussion: Acrylates and methacrylates have been recognized as emerging, important causes of contact allergy and allergic contact disease. A study that spanned 13 years determined that acrylic nail sources and wound dressings represent emerging sources of sensitization. A separate study found that acrylates and methacrylates were significantly associated with allergic contact dermatitis.


Poison ivy (Toxicodendron radicans) is the classic example of acute allergic contact dermatitis in North America. Nickel is the leading cause of allergic contact dermatitis around the world. The incidence of nickel-allergic contact dermatitis in North America is increasing; in contrast, new regulations in Europe have resulted in a decreasing prevalence of nickel allergy in young and middle-aged women.

Dry air renders the skin more susceptible to cutaneous irritants. Sufficiently dry air alone may provoke irritant contact dermatitis. Most cases of winter itch are a result of dry skin from the drier air found during sustained periods of cold weather.

Trauma can cause contact dermatitis. Fiberglass produces direct damage to the skin, usually manifested by pruritus that may result in excoriation and secondary skin damage. Many plant leaves and stems bear small spicules and barbs that produce direct skin trauma. Pressure produces callus formation. Pounding produces petechia or ecchymosis. Sudden trauma or friction produces blistering in the epidermis. Repeated rubbing or scratching produces lichenification. Sweating and friction appear to be the main cause of dermatitis that appears under soccer shin guards in children.

Which of the following statements is accurate about the presentation of contact dermatitis?
A. Cumulative irritant contact dermatitis typically occurs with exposure to strong irritants rather than weak ones
B. A minimum of 10 days is required for individuals to develop specific sensitivity to a new contactant
C. The clinical appearance suggests the etiologic agent in most cases of acute irritant contact dermatitis
D. Onset of dermatitis within 2 weeks of exposure and reports of coworkers or family members affected are among the more important criteria for irritant contact dermatitis.

Answer: B. A minimum of 10 days is required for individuals to develop specific sensitivity to a new contactant.

Discussion: A minimum of 10 days is required for individuals to develop specific sensitivity to a new contactant. For example, an individual who never has been sensitized to poison ivy may develop only a mild dermatitis 2 weeks following the initial exposure but typically develops severe dermatitis within 1-2 days of the second and subsequent exposures.

Cumulative irritant contact dermatitis typically occurs with exposure to weak irritants rather than strong ones. Often, the exposure (eg, water) is not only at work but also at home.

Many cases of contact dermatitis have a similar appearance regardless of the mechanism or cause of the inflammation. Other than distribution and severity, most cases of acute irritant contact dermatitis appear similar, and the clinical appearance does not suggest the etiologic agent. However, some distributions are highly suggestive of the etiologic agent.

Less important subjective criteria for irritant contact dermatitis include the onset of dermatitis within 2 weeks of exposure and reports of many other coworkers or family members affected.

Which of the following is accurate about the workup for contact dermatitis?
A. Laboratory studies are key in positively confirming a diagnosis of contact dermatitis
B. Patch testing is used to confirm that a cutaneous irritant is responsible for a particular case of irritant contact dermatitis
C. Potassium hydroxide preparation or fungal culture is often indicated to exclude tinea in dermatitis of the hands and feet
D. Skin biopsy is routinely indicated in patients with suspected contact dermatitis

Answer: C. Potassium hydroxide preparation or fungal culture is often indicated to exclude tinea in dermatitis of the hands and feet

Discussion: Potassium hydroxide preparation and/or fungal culture to exclude tinea are often indicated for dermatitis of the hands and feet. This helps identify disorders such as tinea pedis.

No single diagnostic test is used for diagnosis of irritant contact dermatitis. The diagnosis rests on the exclusion of other cutaneous diseases (especially allergic contact dermatitis) and on the clinical appearance of dermatitis at a site sufficiently exposed to a suspected or known cutaneous irritant. Laboratory studies are generally of little value in proving a diagnosis of contact dermatitis. However, they may be of value in eliminating some disorders from the differential diagnosis.

Patch testing can be performed to diagnose contact allergies, but no patch test can prove that a cutaneous irritant is responsible for a particular case of irritant contact dermatitis.

Biopsies are of little diagnostic help in contact dermatitis. Most types of contact dermatitis show similar pathologic changes, and allergic and irritant contact dermatitis may not be distinguished with certainty in all cases. However, skin biopsy findings may serve to eliminate some conditions included in the differential diagnosis.

Which of the following is accurate regarding the treatment of contact dermatitis?

A. Patients should avoid using topical antihistamines, including topical doxepin
B. When medication is indicated, topical corticosteroids are no longer considered the mainstay of treatment
C. Removing the tops of large vesicles is routinely beneficial
D. The application of warm-to-hot water is recommended to reduce serous drainage in mild contact dermatitis

Answer: A. Patients should avoid using topical antihistamines, including topical doxepin

Discussion: Patients should avoid using topical antihistamines, including topical doxepin, because of the risk for iatrogenic allergic contact dermatitis to these agents; additionally, sedation can occur if large amounts of doxepin cream are applied.

Topical corticosteroids remain the mainstay of treatment, while various symptomatic treatments can provide short-term relief of pruritus. However, the definitive treatment of allergic contact dermatitis is the identification and removal of any potential causal agents; otherwise, the patient is at increased risk for chronic or recurrent dermatitis. Online resources allow the physician to create a list of products free of allergens to which the patient is allergic.

Large vesicles may benefit from therapeutic drainage (but not removing the vesicle tops). These lesions should then be covered with antibiotic dressing or a dressing soaked in Burow solution.

Many cases of localized mild contact dermatitis respond well to cool compresses and adequate wound care. Cool wet soaks applied for 5-10 minutes followed by air-drying may significantly reduce serous drainage from the site. Clean water, isotonic sodium chloride solution, and Burow solution can all be used with good success. Application of topical calamine is usually of minimal benefit.

Which of the following is accurate about complications and further treatment of contact dermatitis?A. Long-term topical steroid use is routinely indicated for contact dermatitis near or involving the eye
B. Bentoquatam can be used as a replacement for other barrier devices, such as gloves
C. Long-term dietary changes have not shown efficacy in contact dermatitis prevention

D. Shorter courses of corticosteroids may allow poison ivy dermatitis to relapse

Answer: D. Shorter courses of corticosteroids may allow poison ivy dermatitis to relapse

Discussion: Acute severe allergic contact dermatitis, such as from poison ivy, often needs to be treated with a 2- to 3-week course of systemic corticosteroids. Most adults require an initial dose of 40-60 mg. The oral corticosteroid is tapered over a 2- to 3-week period, but a complicated tapering regimen is not necessary given the short duration of systemic corticosteroid use. The systemic corticosteroids must be administered for 2-3 weeks because shorter courses are notorious for allowing poison ivy dermatitis to relapse. Long-acting intramuscular triamcinolone acetonide (Kenalog) 40-60 mg may be used in place of oral prednisone.

Potential complications are associated with the use of steroids, particularly around the eye. The avoidance of long-term steroid use is essential, because such use may cause cataracts, glaucoma, corneal thinning/perforation, and loss of the eye, as well as other problems.

Bentoquatam creates a claylike barrier on the skin that protects against urushiol, the oily resin in poison ivy, oak, and sumac. Bentoquatam is not a replacement for accepted protective devices, such as gloves, boots, and clothing. When exposure cannot be avoided completely, barrier products may protect areas of exposed skin, such as the neck and face.

Individuals with severe dermatitis, particularly if it is a disabling vesicular dermatitis of the hands, may be treated with diets low in minerals and chemicals to which the individual is allergic. A low-nickel diet is the most common, but published diets are available that are low in chromate, cobalt, or balsam of Peru. These diets may be attempted for the occasional allergic patient with severe chronic vesicular dermatitis.

The original article was taken from Medscape. Visit the link below for the original article:

http://reference.medscape.com/viewarticle/881128