Immediate hypersensitivity to iodinated contrast media: diagnostic accuracy of skin tests and intravenous provocation test with low dose.

BACKGROUND: The diagnosis of HSR to iodinated contrast media (ICM) is challenging based on clinical history and skin tests. OBJECTIVE: This study evaluates the negative predictive value (NPV) of skin tests and intravenous provocation test (IPT) with low-dose ICM in patients with suspected immediate hypersensitivity reaction (HSR) to ICM. METHODS: Thirty-seven patients with suspected immediate hypersensitivity reaction to ICM were included retrospectively. Skin tests and a single-blind placebo-controlled intravenous provocation test (IPT) with low-dose iodinated contrast media (ICM) were performed. RESULTS: Skin tests with ICM were positive in five cases (one skin prick test and five intradermal test). Thirty-six patients were challenged successfully by IPT, and only one patient had a positive challenge result, with a grade I reaction by the Ring and Messmer classification. Ten of 23 patients followed up by telephone were re-exposed to a negative tested ICM during radiologic examination; two experienced a grade I immediate reaction. CONCLUSIONS & CLINICAL RELEVANCE: For immediate hypersensitivity reaction to ICM, the NPV for skin tests and IPT with low dose was 80% (95% CI 44-97%).

[A study of 19 cases of allergy to heparins with positive skin testing]. / Étude de 19 cas d'allergie aux héparines prouvée par des tests cutanés.

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. PATIENTS AND 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. DISCUSSION: 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.

Cutaneous adverse drug reaction to oral acetazolamide and skin tests.

BACKGROUND: Few cases of cutaneous adverse drug reactions (CADR) to oral acetazolamide, a non-antimicrobial sulfonamide, have been previously reported, and the interest of acetazolamide skin tests has never been studied. OBJECTIVES: We report a series of ten patients with oral acetazolamide CADR and skin tests. PATIENTS AND METHODS: The files of ten patients with CADR secondary to oral acetazolamide prescribed for cataract surgery in most cases referred between 2001 and 2011 in four French dermatology and allergy departments were retrospectively reviewed. Skin tests with acetazolamide were performed in nine patients and twelve controls. Other sulfonamides were tested in five of ten patients. RESULTS: Seven patients developed maculopapular exanthema and four had acute generalized exanthematous pustulosis. Patch tests were positive for 8/9 patients, prick tests for 2/4 and intradermal tests for 3/3. Patch and prick or intradermal test results were concordant in 2/3 positive subjects. Patch tests for other sulfonamides were negative, as were patch tests in controls. CONCLUSIONS: We report the largest series of CADR to oral acetazolamide (maculopapular exanthema or acute generalized exanthematous pustulosis). A drug eruption after cataract surgery should be investigated for accountability of acetazolamide. In view of this retrospective study, skin tests and particularly intradermal tests appear to be an important contribution to demonstrate accountability.

Comparison of CD63 Upregulation Induced by NSAIDs on Basophils and Monocytes in Patients with NSAID Hypersensitivity.

Background. An in vitro basophil activation test, based on the detection of CD63 upregulation induced by NSAIDs, has been described. Its clinical significance remains controversial. Objectives. In patients with a history of nonallergic NSAID hypersensitivity, stratified according to the severity of the symptoms, to assess with NSAIDs the predictive value of basophil (BAT) and monocyte (MAT) activation tests. Patients/Methods. Sixty patients who had NSAIDs-induced or exacerbated urticaria/angiooedema and 20 controls was included. After incubation with NSAIDs or acetaminophen, leukocytes were analysed for CD63 upregulation. Results. With aspirin, the sensitivity (37%) and specificity (90%) of BAT agree with already published results. In contrast, when patients had had cutaneous and visceral reactions, the frequency of positive BAT 14/22 (64%, P < 0.001) or MAT 10/22 (46%, P < 0.01) were increased. Conclusions. Positive tests were more frequent among patients having a severe hypersensitivity contrasting with the other patients who had results similar to controls.

[Safety of reintroducing platelet-inhibitory doses of aspirin in patients with urticaria or angioedema induced by anti-inflammatory doses]. / Réintroduction de l'aspirine à dose antiagrégante après urticaire ou angio-oedème induits par des doses anti-inflammatoires.

BACKGROUND: Aspirin is one of the most widely prescribed drugs in the world on account of its analgesic, antipyretic, and anti-inflammatory properties. Its effect on platelet aggregation makes it the first choice for prophylaxis in cardiovascular, neurological and obstetric diseases. However, a history of aspirin-induced urticaria and/or angioedema is usually a contraindication for further prescription of the drug. The aim of this article was to demonstrate that patients presenting aspirin-induced cutaneous reactions at anti-inflammatory doses can safely benefit from aspirin reintroduction at platelet-inhibitory doses. PATIENTS AND METHODS: Patients with a history of aspirin-induced urticaria and/or angioedema referred to our department between January 2000 and June 2008 for double-blind placebo-controlled reintroduction at platelet-inhibitory doses for a medical indication were enrolled in this study. RESULTS: Seventy patients with aspirin hypersensitivity as well as a medical indication for this therapy were referred to our department. Of these, 38 (54.3%) had a history of aspirin-induced urticaria and/or angioedema, including three laryngeal oedemas (7.9%). All subjects received platelet-inhibitory doses of aspirin (maximal total dose: 400mg/day) in double-blind placebo-controlled fashion during a one-day hospitalization period. None of the patients presented an immediate hypersensitivity reaction. Only one patient, who had received a cumulative dose of 200mg/day, reported diffuse urticaria and facial angioedema of no clinical significance the following day. He had a history of chronic urticaria. CONCLUSION: This article demonstrates the safety of reintroducing platelet-inhibitory doses of aspirin in patients in whom it is indicated and reporting aspirin-induced urticaria and/or angioedema with anti-inflammatory doses. However, patients with a history of chronic urticaria should undergo a challenge with the lowest platelet-inhibitory dose (75mg/day) in order to minimize the risk of aggravating their condition.

Comparison of two basophil activation markers CD63 and CD203c in the diagnosis of amoxicillin allergy.

BACKGROUND: To confirm allergy to beta-lactam (BL), a basophil activation test in flow cytometry based on CD63 up-regulation was described. CD203c is a more recent basophil activation marker and up to day there is no consensus about which marker is the more sensitive one. CD203c has not yet been evaluated in the diagnosis of BL allergy. OBJECTIVE: The aim of the study was to compare the reliability of CD203c to CD63 for the diagnosis of amoxicillin (AX) allergy, which is nowadays the most frequent BL allergy. METHODS: Twenty-seven patients with an immediate positive skin test (ST) to AX, 20 had had anaphylaxis with AX and 7 had urticaria and/or angioedema, were compared with 14 controls with no allergy to BL and to six patients with delayed positive ST to AX. RESULTS: In the anaphylaxis group, AX induced up-regulation of CD203c in the basophils of 12 patients out of 20 (60%) and of CD63 in four patients (20%) (P<0.02). Two patients out of seven with urticaria or angioedema had a positive result with CD203c and CD63. In patients who had anaphylaxis, ampicillin (AMP) induced CD203c up-regulation in eight out of 12 (67%) patients tested, and CD63 up-regulation in 4 out of 12 (33%) (all patients who had anaphylaxis could not be tested with AMP). False-positive results were observed with CD203c as well as CD63, and for 10 patients indeed this was confirmed by a negative drug provocation test. The origin of conflicting results between CD63 and CD203c might be at least the targeting of basophils based on anti-IgE labelling. Among IgE(+) gated cells, by means of CD33, a marker of monocytes, a contamination up to 50% by monocytes was detected. In contrast to CD63, CD203c is an activation marker specific of basophils with a basal low-level expression in resting basophils. Thus, IgE and CD203c double targeting of basophils avoids the contamination by monocytes. CONCLUSION: CD203c seems to be a more sensitive activation marker of basophils than CD63 for the diagnosis of amoxicillin allergy.