Infectious Disease Detective: A Case of a Mysterious Rash.

Drug reactions are often serious and complex events that can greatly affect patient outcomes. Many of these drug reactions manifest dermatologically by altering the skin's structure or function and are most typically eosinophilic mediated. Fortunately, few drug reactions result in severe consequences for patients, and even fewer are fatal. However, the spectrum of what constitutes a drug reaction is expansive with consistent potential for novel findings. In the case presented, an 81-year-old male patient was found to have whole-body perivascular dermatitis with eosinophils eventually determined to be secondary to a delayed drug reaction. Through this report, the importance of detailed investigation of drug reactions is amplified in the context of rashes of unknown origin and beyond.