Allergic contact dermatitis to propolis

Journal of Drugs in Dermatology, Nov-Dec, 2004 by Patricia T. Ting, Shane Silver

Abstract

A 35-year-old Asian woman was referred to the dermatology clinic with a 2-week history of enlarging, fluid-filled, pruritic lesions on the right foot. The affected area had a recent history of minor trauma for which the patient applied an over-the-counter propolis ointment. At presentation, the patient was also noted to have been using the following, as prescribed by her primary care physician: valacyclovir, ciprofloxacin, terbinafine cream, mupirocin ointment, and 2% hydrocortisone cream. No clinical improvement was observed with these agents. Examination revealed grouped erythematous papules progressing into vesicles and bulla on the lateral side of the right foot. A KOH scraping was negative. We diagnosed the patient with allergic contact dermatitis to propolis.

**********

Case Report

A 35-year-old Asian woman presented with a 2-week history of enlarging, fluid-filled, pruritic lesions on the right foot. The affected area had a recent history of minor trauma for which the patient applied an over-the-counter propolis ointment. As new lesions continued to develop, the patient made several visits to a walk-in medical clinic where she was prescribed the following: valacyclovir, ciprofloxacin, terbinafine cream, mupirocin ointment, and 2% hydrocortisone cream. No clinical improvement was observed with these medications. In addition, the patient continued to use the propolis ointment prior to presentation at our department. Physical examination revealed grouped erythematous papules progressing into vesicles and bulla on the lateral side of the right foot (Figure 1). KOH scraping was negative for fungal hyphae. The patient was otherwise healthy. A diagnosis of allergic contact dermatitis to propolis was made. Use of the propolis ointment was discontinued. The skin lesions resolved following a 3-week course of twice daily clobetasol-17-dipropionate 0.05% ointment.

[FIGURE 1 OMITTED]

Discussion

Propolis allergy is estimated to affect up to 4% of the population (1,2). This compound, also known as "bee glue," is collected by bees from resinous plant exudates (e.g., poplar trees) and used as a sealant for beehives. It contains approximately 50 identified chemical constituents including primary resins and vegetable balsams (50%), waxes (30%), essential and aromatic oils (10%), pollen (5%), and derivatives of caffeic acid esters (1). Propolis has been used since ancient times as an antiseptic, astringent, anti-inflammatory, anesthetic and antioxidant (3). It is also a component of beeswax, as well as wood polishes and varnishes used for musical string instruments such as guitars, violins, cellos, etc (4). Today, propolis can be found in chewing gum, mouthwashes, toothpaste, skin creams, and lotions. Health food stores offer propolis as oral supplements, topical creams, and ointments.

Similar to other cutaneous hypersensitivity reactions, propolis may induce an erythematous pruritic reaction with vesicles and/or bulla on contacted skin. The differential diagnosis includes blistering dermatoses (i.e., bullous pemphigus, pemphigus vulgaris) (5), skin infections (i.e., bullous tinea, shingles), irritant contact dermatitis or chronic eczematous dermatitis. Localized lymphadenopathy has also been reported (6). Allergic contact reactions from ingestion typically manifest as oral mucositis. Anaphylactic reactions were not noted in the literature.

Propolis and/or its components are strong sensitizing agents and in particular, cross-sensitize with products containing balsam of Peru. Balsam of Peru, a common additive in flavoring agents, fragrances, spices and products with peel of citrus fruit (7), is classified as one of the top 10 contact allergens (8) and coexists with propolis sensitivity in 60 to 80% of patch tested patients (2). Propolis sensitivity is thought to be partially responsible for an increase in the number of allergic contact reactions in people that regularly use preparations and cosmetics containing this compound, its constituents and/or sensitizers (9,10).

Allergic contact dermatitis may present in many different forms and is often misdiagnosed for lengthy periods of time and inappropriately managed. Investigations may include skin biopsies and immunofluorescence stains for suspected blistering dermatoses, while bacterial, fungal and viral cultures are indicated for infectious etiologies. A detailed medical history usually elicits clues for irritant contact or chronic eczematous dermatitis. Proper management begins with discontinuation of the offending agent and approximately a 2-week course of high or super-high potency topical corticosteroids (for localized reactions) or systemic steroids (for severe, generalized reactions). Hypersensitivity reactions typically subside within days. Patch testing can be used to confirm allergic contact dermatitis to propolis.

Propolis has long been recognized as a cause of occupational contact dermatitis in beekeepers (3). Allergic contact dermatitis to propolis should also be considered in musicians and instrument makers, in patients with occupations and hobbies where varnished or finished wood is frequently handled, and users of natural food supplements or alternative medicines.