Protein Contact Dermatitis

Protein contact dermatitis is an immediate type reaction to proteins that contact skin which is already damaged by eczema or other inflammation. It produces an itchy, urticarial or eczematous flare within minutes to a few hours of contact.

It occurs mostly in food handlers (cooks, bakers, butchers, fishmongers), healthcare workers using latex gloves, farm and veterinary workers, and hairdressers. It is more frequent in people with chronic hand eczema and atopy.

Causes are raw meat and fish, vegetables, fruit, egg, flour, enzymes, latex, animal dander and saliva, and plant sap. Latex allergic people may cross-react with banana, avocado, kiwi and chestnut.

Pathophysiology.

Proteins penetrate damaged skin and bind specific IgE on mast cells, causing histamine release and a late phase eczematous response. A subgroup also shows delayed type IV hypersensitivity. Skin damage from chronic eczema enables sensitisation, and allergen exposure sustains the dermatitis.

• Itching, burning, erythema, wheals or vesicles within 10 to 30 minutes of contact, settling within hours, or persisting as chronic hand eczema with exacerbations.
• Periungual and finger pulp dermatitis, with recurrent acute paronychia.
• Perioral and facial involvement after contact with foods.
• Systemic features in some: oral allergy syndrome, rhinoconjunctivitis, asthma, urticaria and anaphylaxis.

Red flags.

• Wheeze, throat tightness, widespread urticaria, hypotension or collapse after contact.
• Reaction to latex gloves or balloons.
• Worsening asthma at work.

• Detailed history of reactions within minutes of handling specific materials, including which materials and which surfaces.
• Skin prick testing, including prick-to-prick testing with fresh foods, and specific IgE to relevant allergens and latex.
• Patch testing (readings at 20 minutes and at 48 and 96 hours) and open application tests when needed. These tests carry a risk of systemic reaction, so resuscitation facilities must be available.
• Assessment for respiratory involvement with spirometry or peak flow in exposed workers.

Differential diagnosis. Allergic or irritant contact dermatitis, atopic dermatitis, contact urticaria from non-immunological causes, dyshidrotic eczema, hand eczema from wet work and tinea manuum.

• Avoid the causative protein and latex. Use non-latex gloves (nitrile) with cotton liners, and glove changes to avoid sweating.
• Treat the underlying eczema with emollients and potent topical corticosteroid (betamethasone valerate 0.1%) once daily for 2 to 4 weeks, then twice weekly maintenance.
• Cetirizine 10 mg daily for urticarial reactions. Do not rely on antihistamines for systemic reactions.
• Anaphylaxis: adrenaline 0.5 mg (0.5 mL of 1 in 1000) intramuscularly into the anterolateral thigh for adults, repeated after 5 minutes if there is no improvement, with airway support and intravenous fluid.
• Provide patients with a history of systemic reaction with an adrenaline auto injector, training and a written plan.
• Occupational advice, workplace modification and redeployment when exposure cannot be controlled.

Monitoring. Review at 4 weeks. Reassess for respiratory symptoms at each visit.

Referral and escalation. Refer to dermatology and allergy services for testing and for any systemic reaction. Emergency care is needed for anaphylaxis.