CASE REPORT Utility of an Interferon-c Release Assay for Latent Tuberculosis Diagnosis in a Case of Bullous Pemphigoid

Background: With increasing use of immunosuppressive therapy, including tumor necrosis factor a inhibitors, there is concern about infectious complications, including reactivation of latent Mycobacterium tuberculosis infection. Routine testing prior to administration of systemic immunosuppression includes the tuberculin skin test, which lacks sensitivity and specificity and may be difficult to interpret in the presence of extensive cutaneous disease. Treatment of individuals with latent tuberculosis infection is recommended when immunosuppressive medications are to be employed. Observations: We report a case in which a diagnosis of latent tuberculosis infection in a patient with extensive bullous pemphigoid was clarified by the use of an interferon-c release assay after equivocal tuberculin skin test results. Conclusion: Interferon-c release assays are useful adjuncts to the tuberculin skin test in the diagnosis of latent tuberculosis infection in the setting of extensive cutaneous disease. Antécédents: L’usage de plus en plus répandu de la thérapie immunosuppressive, notamment les inhibiteurs du facteur de nécrose tumoral a, suscite des inquiétudes quant aux complications infectieuses notamment la réactivation de l’infection latente à Mycobacterium tuberculosis. Les examens de routines préalables a ̀ l’administration d’immunosuppresseurs systémiques comprennent le test cutane ́ a ̀ la tuberculine, qui n’est pas assez sensible ou spécifique et qui est difficile a ̀ interpréter en présence d’une affection cutanée généralisée. Le traitement des personnes atteintes d’une infection tuberculeuse latente est recommandé lorsque des immunosuppresseurs doivent être administrés