Utility of patch testing in patients with hypersensitivity syndromes associated with abacavir

A diagnostic test would be useful to help eliminate the associated morbidity and mortality after full-dose rechallenge with abacavir in patients with suspected hypersensitivity. We describe seven patients with syndromes compatible with abacavir hypersensitivity who had positive patch tests. Immunohistochemistry on skin biopsies from the acute prospectively identified patients with rash (n = 3) matched those from positive-patch patients (n = 7), suggesting an identical pathophysiological process. No patients developed systemic symptoms or signs during patch testing.