Most often, the lesions of lichen planus are small purplish papules, solitary or confluent, with exaggerated surface markings. There are, however, several variants. Some lesions develop adherent scales, sometimes vesiculation occurs, and rarely, necrosis and scarring may occur upon resolution. The lesions in Fig. 9-43 are larger and more inflammatory than usual; there is a suggestion of vesiculation and necrosis. The vesicular and bullous forms of lichen planus must sometimes be differentiated from other bullous disorders. Figure 9-44, closely examined, shows a suggestion of scaling. Although the etiology of lichen planus remains a mystery, the clinician must bear in mind that certain lichenoid drug eruptions may be clinically indistinguishable from true lichen planus. The most common agents are gold salts and antimalarial agents. Topical exposure to paraphenylenediamine may have the same result.