[A study of 19 cases of allergy to heparins with positive skin testing].
BACKGROUND
Allergic hypersensitivity to unfractioned or low-molecular-weight heparins is uncommon but is known, and in particular the most common form is localized dermatitis, although such cases have seldom turned into maculopapular exanthema. Since cross-reactions with other heparins are frequent, identification of therapeutic alternatives is essential.


METHODS
This retrospective study included patients referred to the Department of Dermatology and Allergology at Tenon Hospital between 2000 and 2012 with suspicion of allergy to unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) and sensitized to at least one heparin (i.e. positive skin tests to at least one heparin). The heparins and hirudins used were tested in the forearm by means of intradermal skin tests. All patients were contacted in 2012 to establish whether they had used some form of heparin since the cutaneous allergy tests.


RESULTS
Nineteen patients had at least one positive skin test for heparin; 1 patient had presented anaphylactic shock, while 18 others had presented localized eczema (12) or generalized dermatitis (6). The heparin most often responsible for these adverse reactions was enoxaparin (13/19). An LMWH was responsible in most cases (18 vs. 1 with UFH). Of these 18 patients, 16 also presented positive skin tests for UFH, 9 for synthetic heparinoid and 1 for hirudin. 11/19 patients were tested for fondaparinux (a synthetic pentasaccharid) and all had negative skin tests. 5/7 patients with negative skin tests had taken fondaparinux without any visible reaction, whereas 2 who also tested negative experienced localized eruption at the injection site.


CONCLUSIONS
Our results underline the greater frequency of delayed hypersensitivity reactions compared with immediate reactions to heparins. Skin tests can help to identify substitution molecules. Fondaparinux might be an alternative but certain diagnosis relies on rechallenge.
Service de dermatologie et allergologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France. Electronic address: cel.phan@gmail.com.
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Phan
Service de dermatologie et allergologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France.
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Vial-Dupuy
Service de dermatologie et allergologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France.
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Autegarden
Service de dermatologie et allergologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France.
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Amsler
Service de dermatologie et allergologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France.
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Gaouar
Service de dermatologie et allergologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France.
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Abuaf
Service de dermatologie et allergologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France.
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Pecquet
Service de dermatologie et allergologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France.
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Francès
Service de dermatologie et allergologie, hôpital Tenon, AP-HP, 4, rue de la Chine, 75020 Paris, France.
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Soria
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000707:Anaphylaxis / Q000175:diagnosis / Q000209:etiology; D000925:Anticoagulants / Q000009:adverse effects*; D003429:Cross Reactions; D004306:Dose-Response Relationship, Immunologic; D003875:Drug Eruptions / Q000175:diagnosis / Q000209:etiology*; D004342:Drug Hypersensitivity / Q000175:diagnosis / Q000209:etiology; D004485:Eczema / Q000139:chemically induced* / Q000175:diagnosis; D005260:Female; D000077425:Fondaparinux; D006493:Heparin / Q000009:adverse effects*; D006495:Heparin, Low-Molecular-Weight / Q000009:adverse effects; D006496:Heparinoids; D006629:Hirudins; D006801:Humans; D008297:Male; D008875:Middle Aged; D011134:Polysaccharides; D012189:Retrospective Studies; D012882:Skin Tests; D055815:Young Adult
D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D006496:Heparinoids; D006629:Hirudins; D011134:Polysaccharides; D006493:Heparin; D000077425:Fondaparinux
Allergic hypersensitivity; Allergie; Dermatitis; Eczéma; Fondaparinux; Heparin; Hypersensibilité; Héparine; Skin tests; Tests cutanés