Cutaneous drug eruptions including serum sickness-like reaction, symmetrical drug-related intertriginous and flexural exanthema, and drug-induced lupus.

Cutaneous manifestations of drug reactions are common yet vary widely in their appearance and degree of internal organ involvement. Serum sickness--like reactions, symmetrical drug-related intertriginous and flexural exanthem, granulomatous drug eruption, pseudolymphoma, and drug-induced lupus are medication-induced conditions with dermatologic presentations. Many of the conditions discussed are relatively rare but nonetheless demand our attention and understanding. Some of the conditions presented may be more likely encountered in the hospital setting, as is the case with serum sickness-like reactions and drug-induced lupus, whereas others may present to outpatient clinic for diagnosis. Given the similarities in clinical history of patients presenting with these conditions, an understanding of the clinical presentation, pathophysiology, culprit medications, histologic appearance, and serologic characteristics is warranted to correctly diagnose and manage these uncommon adverse reactions. We also discuss how to differentiate some of these conditions from more serious mimickers, as in the case of pseudolymphoma drug reaction mimicking a true lymphoma and drug-induced lupus mimicking acute systemic lupus erythematosus.