The quince, or Cydonia oblonga, is a small deciduous tree which belongs to the Rosaceae family. It is native to warm-temperate southwest Asia in the Caucasus region. In Spain, quince is scarcely harvested in some regions of Andalucia and Valencia. Interestingly, it has been described that quince extracts show immunomodulatory effects with potential therapeutic activity.1–3 Quince extracts have also been used in fragrances and pastry. To the best of our knowledge there are no previous published reports of quince-monosensitised patients, which highlights the relevance of this case. We describe a case of a 57-year-old woman who ate a self-harvested raw peeled quince which caused an immediate glottic and lingual angio-oedema requiring epinephrine and corticosteroid treatment.
A 57-year-old woman was referred to our outpatient allergy division due to an immediate glottic and lingual angio-oedema after the ingestion of a small piece of a raw peeled and self-harvested quince. She reported complete absence of skin contact to it, as the quince was completely peeled by her husband, due to the development of erythematous pruritic hands immediately after touching the former fruit several times before this reaction. However, her husband had ingested the rest of the quince showing no symptoms. She was transferred to the Emergency Department of our University Hospital where mandatory treatment with intramuscular epinephrine, dexclorpheniramine and methylprednisolone was subsequently fulfilled. Before the current episode, the patient had previously shown complete tolerance to physical exposition and/or ingestion of quince (both peel and pulp). She reported neither drug coingestion, nor fever or infection coincidental in time with the reaction, and complete absence of atopic background. Additionally, she did not complain about spring-related symptoms nor fruit or vegetable allergy. Moreover, she had never ingested quince jelly. An allergy work-up was performed after informed consent.
Skin-prick-tests (SPT) were performed with the most common aeroallergens in our area, as well as with other Rosaceae family members and profilin, obtaining negative results for all of them. Prick-by-prick testing to quince flesh (raw) showed strongly positive results (wheal equals to the size of histamine wheal and with six atopic patients as negative controls) while quince peel (raw and boiled) and boiled flesh resulted negative.
The patient blood test showed that the total immunoglobulin E (IgE) concentration was 104UI/L and specific-IgE to Pru p 3 was 0.0kU/L (ImmunoCAP System, Thermo Fisher Scientific™). Serum specific IgE analysis was performed using an IgE dot-blot assay (Bio-Rad™, Hercules™, California, USA) according to the manufacturer's instructions (Fig. 1A). Proteins of the quince peel were obtained by homogenisation and solubilisation with phosphate-buffered saline. Insoluble proteins were eliminated by centrifugation and filtration. Soluble proteins were dialysed against water in order to achieve lyophilisation. Then, 50mg of quince extract was reconstituted in 250¿L of buffer phosphate saline and 0.12, 0.06, 0.03, 0.015 and 0.0075mg/mL of protein was introduced onto the wells to perform the assay. A polyvinylidene fluoride transfer membrane was used. Serum was applied with a blocking buffer (phosphate buffered saline containing 1% bovine serum albumin and 0.05% Tween, 1:1, v/v). The antibody was a mouse anti-human IgE (Fc) Horseradish peroxidase (HRP) (Southern Biotech™) and the Western Lightning Plus-ECL™ system (PerkinElmer Life and Analytical Sciences™, Shelton, Connecticut, USA) was used as substrate. The patient's serum was positive to quince and negative to Dermatophagoides pteronyssinus (Dpt) extract as control. Dpt extract was likewise resuspended in blocking buffer. Serum from a non-allergic patient was used as a negative control (control 1). Other controls were performed using Dermatophagoides pteronyssinus extract, the serum from a patient allergic to Dpt (control 2, positive), and the serum from a non-allergic patient (control 3, negative).
A. Results of IgE Dot Blot Assay. Responses of serum from our patient to different concentrations of protein from quince (0.12, 0.06, 0.03, 0.015 and 0.0075 mg /mL) are shown (upper image). The response to Dermatophagoides pteronyssinus of serum from a patient who was sensitized to D. pteronyssinus extract, which was used as a positive control of the assay, is also shown (positive control). The response to D. Pteronyssinus of serum from a non atopic patient is shown (negative control). B. Quince (Cydonia oblonga), a member of the Rosaceae family.
As the ingestion of quince is generally scarce, the frequency of allergic reactions subsequent to its ingestion remains elusive, and this likely accounts for its allergenic characteristics.4 Quince fruit is usually ingested as cooked pastry but not raw, as in this case, so the frequency of the elicited hypersensitivity is unknown (Fig. 1B). Some authors have suggested that Rosaceae fruit allergy without pollinosis is severe5; patients suffering from the former fruit hypersensitivity are frequently seen with systemic involvement, mainly anaphylaxis, often without oral allergy syndrome, eliciting up to a 40% of anaphylactic reactions after ingestion.5 The patient did not have atopic background, which reinforces the odds to develop severe symptoms as stated before. Madrid area is a birch-free region, so PR-10 foods and PR-10 related pollens were not investigated. Besides, the patient did not complain about other PR-10 related foods such as Fabaceae, Apiaceae, Betulaceae, Anacardiaceae, Solanaceae, Asparagaceae or Cucurbitaceae.
Moreover, the patient was advised to strictly avoid quince and quince-containing foods and was instructed in the use of epinephrine autoinjector which was likewise prescribed. Pruritic erythema of the hands after contact with quince is likewise scarcely observed. It is known that those involved in fruit growing, handling and processing, are at risk from topical exposure to develop contact urticaria.6 Both contact hypersensitivity and non-allergy topical reactions related to fruits could also develop, due to volatile substances that can be irritating to the skin. The former could constitute one of the reasons why this specific reaction has been scantily reported, as quince is not frequently encountered in supermarkets or groceries. In this exceptional case, self-harvest for self-consumption of the quince made it accessible to hand contact, as the patient did not wear gloves to collect it, possibly triggering a sensitisation which could have led to such a severe reaction, in which Pru p 3 sensitisation was not involved as previously reported.
We have presented a singular case of an IgE-mediated reaction to quince, in a monosensitised patient. To the best of our knowledge, this is the first case reported in the literature in which monosensitisation to quince showed such a cumbersome reaction after prior sensitisation due to hand contact. An IgE-mediated mechanism was demonstrated both by skin and in vitro tests. Moreover, the patient did not have an atopic background, which reinforces the importance of this case.
Lastly, performing skin prick-by-prick tests with fresh quince (both raw and boiled) in patients with immediate hypersensitivity reactions to this fruit is suitable and recommended, as proven in this case. Further investigation must be carried out in order to clarify the culprit allergens as regards the up-to-date immunomodulatory effects of this fruit.
Conflicts of interestThere is no known conflict of interests for the authors.
Financial supportThis work was partially supported by a grant from Comunidad de MadridS2010/BMD-2502 MITIC.
Author contributionsDAA and MAM were involved in study design, laboratory assessment, data analysis and writing manuscript.
MJSG, MRR, JBE and DAA were involved in patient follow-up, pharmacologic advisory and writing manuscript.
FP was involved in skilled technical assessment.
Ethical disclosuresConfidentiality of dataThe authors declare that no patient data appears in this article.
Right to privacy and informed consentThe authors have obtained the informed consent of the patients and/or subjects mentioned in the article. The author for correspondence is in possession of this document.
Protection of human and animal subjectsThe authors declare that no experiments were performed on humans or animals for this investigation.
