Are You Confident of the Diagnosis?
What you should be alert for in the history
Diagnosis of occupational contact dermatits (OCD) is often difficult to prove. Much of the accuracy depends on the skill level, experience, and knowledge of the medical professional who makes the diagnosis and confirms the relationship with a workplace exposure. A careful and detailed medical and occupational history is critical for the diagnosis. Because the symptoms and presentation of irritant contact dermatitis (ICD) and atopic contact dermatitis (ACD) are so similar, it is extremely difficult to distinguish between the two forms of dermatitis without patch testing. An initial screening series such as the TRUE test can be performed by most dermatologists but it is important to keep in mind that without the use of more comprehensive series, potential allergens may not be detected.
Additional patch test series to consider might include the following: rubber additive chemicals, bakery chemicals, dental materials, metals, adhesives and glues, oil and cooling fluids, epoxy resins, hairdressing chemicals, isocyanates, medicaments, and plants.
Some suspected allergens are not commercially available for patch testing. The interpretation of results of patch testing with new compounds is fraught with pitfalls as it can be difficult to distinguish an irritant from an allergic reaction. It is much safer to perform preliminary patch testing of new chemicals with the open method prior to closed patch testing. Protocols can be found for testing with unlisted or unknown substances in Fisher’s contact dermatitis.
Characteristic findings on physical examination
The diagnosis of occupational contact dermatitis is suspected when patients present with a dermatitis in exposed areas of skin. The hands and the forearm have the greatest contact with irritants and allergens and are the most commonly affected sites.
The following questions can be helpful in determining the work-relatedness of the dermatitis:
Is the clinical appearance consistent with a contact dermatitis? Patients often falsely identify any rash as being work related (eg, tinea, urticaria, granuloma annulare). The clinician must first decide if the appearance is consistent with a dermatitis.
Are there workplace exposures to potential irritants or allergens? Be suspicious when it is a new job or when new processes are introduced into the workplace. A higher index for allergy should exist if multiple workers are affected in a similar fashion.
Is the anatomic distribution of dermatitis consistent with cutaneous exposure in relation to the job task? The hands and forearms are the most commonly affected areas since they have the greatest contact with allergens and irritants. The thighs, upper back, armpits, and feet can be affected if the chemical gets onto the clothing. Dusts can produce an irritant dermatitis under areas of occlusion from clothing including under the collar, belt line, tops of socks or shoes, and flexural areas such as the antecubital and popliteal fossae.
Is the temporal relationship between exposure and onset consistent with contact dermatitis? Irritant reactions occur soon after the exposure (decrescendo phenomenon- reaction reaches its peak quickly and then starts to recover) whereas occupational ACD may take several weeks to develop. Occupational dermatitis may tend to improve during weekends or holidays although this is not always the case with a chronic dermatitis.
The following questions can be used ( in a questionnaire format) when occupational contact dermatitis is being considered:
Date of onset
Site of onset
Patient’s description of symptoms
Material contacted other than at work (cosmetics, plants, chemicals)
Current dermatologic medications
Previous treatment by company physician
Describe protective clothing
Describe protective gloves
Handwashing: include frequency and type of cleanser
Bathing: include frequency and type of cleanser
Body lotion and type
Hand lotion and type
Facial cosmetics and type
Use of deodorant or cologne
Hair dye or bleach
Present and previous occupations with dates of employment
Current employer with contact information and dates employed
Lost time from work
Description of work when dermatitis started
Materials contacted at work including new materials
Effect of weekends and vacations
Are other workers affected?
The clinician should suspect ACD if the pattern of dermatitis is changing or if the dermatitis is worsening. Physical examination of occupational ACD initially reveals erythema underlying small vesicles and papules in an acute dermatitis. After several days crusts and scales form. With chronic exposure, deep fissures, scaling, and hyperpigmentation can occur. Intense vesiculation should increase the suspicion of ACD, but it may be absent in chronic ACD. Clinical lesions are more intense in the contact areas (eg, hands and forearms), but their limits may be poorly defined.
Physical examination in an acute occupational ICD may show erythema and edema with vesicles or bullae along with oozing and pustules. Necrosis and ulceration may be seen with corrosive materials. A more subacute or chronic occupational ICD is characterized by hyperkeratosis, fissuring, glazed, or scalded appearance. The dermatitis is usually sharply circumscribed to the contact area (eg, sharp cutoffs at the wrists from irritants trapped under gloves).
Patterns of dermatitis can serve as clues to the diagnosis. A unilateral hand dermatitis may be seen on the dominant hand. An example might be a florist with an allergy to alstroemeria (tuliposide A) with a dermatitis on the fingertips of the hand used to pull off the leaves and stems. Dermatitis on the dorsum of the hands with sharp cutoffs at the wrists would be consistent with a glove-induced ACD.
Irritant reactions would tend to involve the finger web spaces (apron pattern: localized involvement of the finger web spaces with extension onto the dorsal and ventral surfaces; Figure 1). Fingertip dermatitis or pulpitis can be seen in a worker handling allergens with the tips of the fingers (Figure 2).
Some work exposures may present with an airborne distribution if the allergen is volatile or in a mist. Accentuated areas might include the face and neck with accentuation around the eyes, V of neck, nasolabial folds and behind the ears (Wilkinson’s triangle).
Expected results of diagnostic studies
Histopathology is typically not helpful in distinguishing the cause of the dermatitis and will show features in the spectrum of acute to chronic dermatitis. Potassium hydroxide preparation or fungal culture to exclude tinea are often indicated when involvement is on the hands or feet.
The differential diagnosis of occupational contact dermatitis includes the following entities:
–Non-occupational contact dermatitis (distinguished by history and physical examination);
–Psoriasis(This is especially confusing when presenting on the hands. Look forwell defined plaques and evidence of psoriasis elsewhere);
–Atopic dermatitis (usually presents in childhood and associated with a positive personal or family history of atopy);
–Tinea (perform KOH or fungal culture)
–Mycosis fungoides (distinguished by histopathology);
–Lichen simplex chronicus
–Contact urticaria (more transient lesions)
Who is at Risk for Developing this Disease?
Contact dermatitis is the most common occupational skin disease; 90% to 95% of all occupational skin disease is due to contact dermatitis; 80% of OCD is caused by nonimmunologic reactions to chemical irritants (ICD) and 20% to allergic reactions (ACD). The most important risk factor for OCD is the exposure to irritants. Common irritants are water (wet work), detergents, hand cleaners, chemicals, cutting fluids, and abrasives. Workers at risk for OCD include but are not limited to those working in the following industrial sectors:
Other risk factors include:
–Age ( children and elderly are more susceptible to ICD)
–Gender (women more susceptible to ICD)
–Environmental factors: wet work, extremes of humidity both low and high, friction
What is the Cause of the Disease?
Broadly speaking, OCD is an inflammatory condition of the skin resulting from cutaneous contact with materials found in the workplace.
Pathophysiology of occupational ACD is a classic delayed-type hypersensitivity or a type IV immunologic reaction. It is immune-mediated rather than antibody mediated. The allergen or hapten sensitizes the skin and creates memory lymphocytes. The small chemical molecules responsible for ACD must bind to antigen-presenting cells or Langerhans cells, which are situated within the suprabasilar layer of the epidermis. Irritant reactions may impair the barrier and increase susceptibility to sensitization.
ICD is a nonspecific response of the skin to direct chemical damage that releases mediators of inflammation predominantly from epidermal cells.
The severity of dermatitis is highly variable and depends on many factors including:
–Characteristics of the hazardous chemical, eg, pH, viscosity (irritant and/or allergen)
–Concentration of the hazardous agent (irritant and/or allergen)
–Environmental factors, eg, temperature and humidity
–Condition of the skin, eg, intact, photodamaged, intrinsic age, xerosis, etc
Systemic Implications and Complications
There are a number of case reports and series describing workers with occupational dermatitis and respiratory symptoms. This has been reported with a number of exposures including isocyanates used in polyurethanes. Workers should be questioned as to the presence of any temporal work-related respiratory symptoms. If these exist, consider consultation with an expert in occupational medicine.
Table 1. Treatment options for OCD.
|Medical Treatment||Physical Modalities|
|Topical corticosteroids||Avoidance protocols|
|Topical calcineurin inhibitors
Narrow band (short wavelength) UVB
Psoralen photochemotherapy (PUVA)
Optimal Therapeutic Approach for this Disease
The highest priority in treating occupational dermatitis is to identify and avoid causative allergens and irritants in the workplace. Strategies for preventing occupational contact dermatitis include personal measures, environmental measures, and administrative measures (Table 1).
When the dermatitis develops use of topical treatment is helpful. Topical corticosteroids are the mainstay of treatment, but prolonged use can result in atrophy of the skin resulting in a higher susceptibilty to irritant dermatitis. For this reason their use in irritant dermatitis is controversial. Topical calcineurin inhibitors including tacrolimus and pimecrolimus can be used as an alternative to topical corticosteroids in occupational ICD and ACD.
Oral corticosteroids are a mainstay in the acute phase of the dermatitis. Similar to other causes of acute contact dermatitis, patients typically require at least a 2-week course to prevent rebound phenomenon. Most adults require an initial dosage of 40 to 60mg/day.
Phototherapy with narrow band UVB can be used to suppress a more chronic dermatitis. Topical or systemic PUVA can be considered for a more chronic hand dermatitis.
Personal measures include applying emollients, adjusting methods for personal cleansing and hygiene, and wearing personal protective equipment as referenced in Fisher’s Contact Dermatitis, 6th edition, pp. 491-493. Emollients improve barrier repair in chronic occupational dermatitis. Options include petrolatum-based emollients, which are cost-effective and accessible, or emollients containing skin-related lipids.
The excessive use of personal hygiene may lead to misuse of soaps and detergents and lead to worsening ICD. When possible, soap substitutes should be used for washing. Key components for prevention of hand dermatitis include the following: Use of protective gloves for wet work and cotton liners if the gloves are to be worn longer than 10 minutes; no rings worn at work; protective gloves in wet work at home.
Environmental measures include substituting chemicals that are less irritating or allergenic. They also include establishing engineering controls to reduce exposure.
Administrative controls involve education in workplace safety with emphasis on personal and occupational hygiene.
Explain the pathogenesis to the patient. In cases of occupational ACD emphasize that even minute amounts can promote the dermatitis and that usually complete avoidance is required. In cases of occupational ICD, emphasize measures to protect and repair the skin’s barrier. This includes appropriate protective measures, proper hygiene, avoidance of irritants, and liberal use of emollients.
Record keeping by the clinician should be meticulous. It may be necessary to state in the record the causative factors and the link to the workplace as many cases of OCD involve worker’s compensation claims.
Provide occupational counseling to the affected worker in coordination with the employer. The worker may need reassignment to an area where exposure is minimized or nonexistent. In certain cases be prepared to recommend a career change as OCD often has a poor prognosis.
The physician evaluating these patients needs to be well-versed in workers’ compensation protocols.
Unusual Clinical Scenarios to Consider in Patient Management
Remember that the hands are frequently involved in OCD. Protective gloves if used properly are the mainstay to eliminate exposure of the hands to hazardous substances. If not chosen and used correctly, protective gloves can worsen or cause an occupational ICD. When possible, have the worker bring his used gloves to the clinic for evaluation.
The following are the mechanisms whereby a gloved hand can be exposed to harmful substances.
Contamination prior to donning glove
Permeation, which is dependent on glove material, substance, and exposure duration
Penetration through physical holes in the glove
Degradation of the glove
Breakthrough time, which is dependent on the substance, the glove material, and length of exposure.
There are a number of references that can be helpful in selecting the proper glove for the specific work environment.
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