Case history: 32-year-old M. Markus, civil engineer, non-smoker, without family and personal atopic history, suffered from nocturnal dyspnea, cough attacks and rhinoconjunctivitis for more than one year. Various attempts at therapy were unsuccessful; only during the vacations was the patient practically free of symptoms. With a suspicion of allergic asthma with house dust allergy (until 3 months before the referral there was a cat in the household), the referral to the allergy ward was finally made by the family doctor.
Allergological clarification
Routine prick tests for inhalant allergens, incl. Cat epithelia, and on food in the survey all ran negative. The total IgE serum level was in the upper normal range at 105 kU/l, and the phadiatop test as inhalation screen and specific IgE (RAST) to house dust mites were negative at <0.35 kU/l. The blood count showed an eosinophilia of 7.9%, and the metacholine provocation test showed a drop in FEV1,with a cumulative 800 µg of metacholine. Scarification tests carried out at a later date using intrinsic dust samples from the vacuum cleaner were negative. At that time, no explanation was found for the asthma and rhinoconjunctivis symptoms until Commissioner “Chance” came to the rescue.
Course
On a Saturday morning while cleaning a green plant standing 1.5 m from the bed, lip swelling, pruritic generalized urticarial efflorescences and whistling breathing occurred. The leaves and twigs brought for testing were Ficus benjamina (Fb) (Fig. 1). A rub test with the finely powdered leaf and a prick-to-prick test with leaf and sap from the stem were strongly positive (wheal of 9 mm diameter) (Fig. 2). Prick tests in five control subjects were negative. Specific IgE determination with the RAST test available at that time was strongly positive at 66 PRU/ml. After removal of the ficus plantfrom the apartment, there was freedom from symptoms within three months. Bronchial hypersensitivity decreased to a PD20 of 2550 µg metacholine and RAST decreased to 22 PRU/ml.
Diagnosis
Bronchial asthma allergicum, allergic rhinoconjunctivitis and acute urticaria in monovalent sensitization to Ficus benjamina.
Comment
In 1985, Axelsson et al. [1] first pointed to Ficus benjamina (Fb) as an inhalant allergen in occupationally exposed gardeners and employees of plant rental companies. Later, they also reported non-occupationally exposed atopic patients who were sensitized by contact with the plant and suffered from corresponding respiratory symptoms [2]. The case of monovalentFb allergyin a nonatopic patient described above was published by us in 1993 [3]. In the same year, a publication from the Allergy Polyclinic in Basel and the Allergy Ward in Zurich was published, reporting 12 cases suffering from Fb allergy. The majority of patients were polyvalently sensitized. Only two individuals (including the one described above) had monovalent hypersensitivity to Fb. [4]. Three interesting casuistry are elaborated below.
Ficus benjamina, occasionally called F. benjamini , is a member of the genus Ficus, which includes over 600 species and belongs to the mulberry family (Moraceae). Names in English are weeping fig, Java or Ceylon willow and Bali [2] or willow fig tree [5]. The German name given is Benjamin tree [5], but the term Ficus benjamina is best known in our country. Fb grows naturally in subtropical and tropical regions, where it can reach a height of many meters. Its leaves are small and entire and can occupy a surface area of over 3 m2 for a plant about 1.5 m tall [1]. The insect-transported pollen lies surrounded by greatly reduced petals in an inverted, later fleshy fruiting body, which in Fb impresses as a small, red berry-like structure. Characteristic of all Ficus species is the content of a milky sap (latex) in the leaves and the branches of the plant (Fig. 1, detail). Other well-known representatives of the Ficus familyare Ficus carica. with the edible fig as a fruit body and Ficus elastica the Indian large-leaved rubber tree, from which rubber is also obtained. Moreover, the Aztecs made their paper, amatl, from the bark bast of South American ficus species [6].
Diseases caused by members of the genus Ficus have long been of importance in occupational medicine. Ficus carica contains the phototoxic substances 5- and 8-methoxypsoralen, which is why phototoxic dermatitis has been described in fig pickers in particular, but irritative contact eczema is also known [7]. Although pollen from North American wind-pollinated members of the mulberry family can cause severe pollinotic symptoms, pollen from Ficus species does not appear to cause respiratory symptoms due to its specialized pollination [8].
In our latitudes, Fb serves ornamental purposes, it is a frugal, popular and, accordingly, widespread ornamental plant. The allergen is localized in the latex and is either released when leaves and branches are cut, or is probably delivered by excretion to the leaf surface, where it can bind to the dust lying on it and lead to the corresponding respiratory symptomatology.
A serological study revealed considerable cross-reactivity between different representatives of the genus Ficus, which decreased according to the degree of relatedness [9]. Characterization of the Ficus benjamina latexallergen by the immunoblot technique revealed eleven bands, three of which were so-called “major allergens” with molecular weights of 25, 28, and 29 kD. Interestingly, evidence for cross-reactivity with latex from Hevea brasiliensis [10], the potent allergen in latex-containing rubber articles [11,12], was also detected in some sera.
In summary, two groups can be identified in patients who have developed respiratory allergy to Fb: Non-atopics who are occupationally or non-occupationally highly exposed, and occupationally and non-occupationally mostly moderately exposed atopics. With today’s ubiquitous distribution, Ficus benjamina is often present in the workplace, and even non-occupational, low-impact but prolonged exposure can lead to sensitization.
Casuistry
The 35-year-old woman had suffered from recurrent rhinoconjunctivitis and perennial nocturnal eye and nasal symptoms for two years, especially during the summer months on her balcony. The history for atopic diseases was negative. No symptoms on contact with the two own cats. For several years, a Ficus benjamina stood in the bedroom next to the bed, and on the balcony she grew a bonsai ficus. Cutting back the bonsai triggered urticarial exanthema on uncovered areas of the body. Skin tests with inhalant allergens including feline epithelium and mites were negative. A prick-to-prick test with the leaf of Fb and the bonsai were 4+ positive, and a prick test with the leaf and twig extract were 2+ positive. A conjunctival provocation test was also positive. Spirometry revealed normal values. Total IgE was 116 kU/l, and an inhalation screen (SX-1) was negative. Specific IgE to Ficus spp . were positive (class 4; 21.3 kU/l). Thus, the diagnosis of rhinoconjunctivitis allergica and allergic contact urticaria in monovalent sensitization to Fb could be made. After removing the ficus from the bedroom and avoiding contact with the bonsai, no more complaints occurred.
The 41-year-old secretary with a family history of atopic disease (mother asthmatic, brother suffering from hay fever) suffered from mild rhinoconjunctivitis during the last two pollen seasons. During the winter months, she experienced morning itching of the conjunctiva and discrete swelling of the eyelids, for which she sought ophthalmologic treatment. From spring on, acute recurrent severe swelling of both eyelids in the sense of angioedema occurred, which was the reason for an allergological clarification. Prick tests with inhalation allergens were positive to tree, grass, and herb pollens. Scratch tests with self-dusts and a prick-to-prick test with Fb ‘s leaf were negative. Total IgE was 385 kU/l, specific IgE to Ficus spp. was positive (class 3; 8.6 kU/l), specific IgE to grasses and ash was also detectable in class 3 and to alder and mugwort in class 2. Blood eosinophilia of 10%. Despite a negative prick test for Fb, the diagnosis “allergic conjunctivitis and eyelid swelling (angioedema) due to sensitization to Ficus benjamina and rhinoconjunctivitis pollinosa” could be made based on the detection of specific IgE to Ficus spp. During the workup, the patient experienced two additional episodes of marked eyelid swelling, which required temporary use of systemic corticosteroids and antihistamines. After removal of the ficus from the home, freedom from symptoms occurred during a six-month follow-up period.
The 21-year-old dental assistant with mild seasonal rhinoconjunctivitis from February to July had been suffering for one year, with onset in winter, additionally from perennial symptomatology with obstructed nasal breathing, nasal flow and, most recently, asthmatic complaints. During the vacations at the seaside she was practically free of complaints. At home she had two cats, a chinchilla and there was dog contact at her parents. She owned a Ficus benjamina, and there was also such a green plant in the dentist’s office. She had noticed that when she cut and cleaned the plant at home, skin redness and swelling appeared each time. A connection with the respiratory symptoms and Fb was not apparent to her. The routine prick and intradermal tests with inhalation allergen incl. Pollen (ash pollen was not routinely tested at that time!) was negative, also scarification tests with self-dusts and with cat, chinchilla and dog epithelia. A prick-to-prick test with ficus leaf was questionably positive, but a RAST/CAP with Fb was massively positive with class 5 (73 kU/l), but negative with house dust mite, animal epithelia, and latex. A metacholine provocation test showed a 35% drop in FEV1 after a cumulative 800 µg of metacholine. Four months after removal of the ficus at home and at the store, she was symptom-free except with exertion. Metacholine test remained positive at PD20 of 800 µg metacholine, and sIgE on Fb dropped slightly to class 4 (30.1 kU/l). Only serologic testing confirmed a monovalent Fb allergy in an apparently nonatopic patient.
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- Axelsson IGK, Johansson SGO, Zetterström O: A new indoor allergen from a common non-flowering plant. Allergy 1987; 42: 604-11.
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DERMATOLOGIE PRAXIS 2017; 27(2): 26-30
DERMATOLOGIE PRAXIS 2018 Special Edition (Anniversary Issue), Prof. Brunello Wüthrich