| It is often idiopathic in origin, but may be associated with multiple sclerosis, sarcoidosis, syphilis, Lyme disease, and ocular lymphoma. |
| Most etiologic studies of sarcoidosis have used an epidemiologic approach, but the disease poses particular difficulties. |
| Papules of sarcoidosis may be of various colors, including red, reddish-brown, violaceous, translucent, or hyperpigmented. |
| This is seen in longstanding sarcoidosis, in which asymptomatic, violaceous nodules are seen on nose, fingers, and ears. |
| Granuloma formation in sarcoidosis may be a stereotypical response to multiple infectious and noninfectious agents. |
| The etiology of the systemic granulomatous disease sarcoidosis remains obscure. |
