Chronic Spontaneous and Inducible Urticaria Associated With Mycoplasma pneumoniae Infection.

Acute childhood urticaria is a common disorder that has been associated with infections. In a few children, it may last for more than six weeks, thereafter it is characterized as chronic urticaria (CU). We report two cases, one suffering from chronic spontaneous urticaria and one chronic inducible urticarias (dermographism and cold urticaria). Both children had concomitant respiratory symptoms that were associated with Mycoplasma pneumoniae (MP) infection. Urticarias' symptoms and signs were refractory to regular antihistamines dose but showed marked improvement or complete resolution following clarithromycin administration. CU response to antibiotics pointed strongly to a potential causative role of MP in the pathogenesis of chronic spontaneous and chronic inducible urticarias. It is not clear if MP was the etiopathogenic cause or just the trigger. Nevertheless, refractory to antihistamines urticarias associated with MP infection may respond to antibiotics, which should be considered as an alternative therapeutic approach.

Allergy skin testing in predicting adverse reactions to fluorescein: a prospective clinical study.

PURPOSE: To evaluate allergy skin testing as a diagnostic tool of adverse reactions to fluorescein and whether allergy and previous sodium fluorescein angiography (SFA) act as predisposing factors. METHODS: Patients with adequate indication for fluorescein angiography and normal skin responsiveness were subjected to allergy skin-prick and intradermal tests for fluorescein, followed by SFA. During SFA, adverse reactions were monitored and classified as mild, moderate or severe. Previous SFAs and adverse reactions as well as the presence of atopy were also registered. RESULTS: One thousand and thirty-seven patients were enrolled in the study and 1284 SFAs were executed. Forty-four patients (4.3%) developed 55 adverse reactions; among them 50 (3.8%) were mild, three (0.2%) moderate and two (0.16%) severe. None of the reactors produced positive skin tests to fluorescein. Patients with atopy and previous SFAs were not more susceptible to adverse reactions. CONCLUSION: The vast majority of adverse reactions to fluorescein are mild and not attributed to immunological mechanisms. Allergy skin tests cannot predict non-immunological reactions but their utility remains substantial in predicting anaphylaxis during SFAs and must be performed in patients reporting risk factors in their past medical history.