[Plaques opalines: a rare form of secondary syphilis of the oral mucous membrane].

A 37 year old woman presented with a 4-month history of "plaques opalines" of the oral mucosa complaining of a rough feeling in her mouth and burning when swallowing. On the basis of clinical, histological and serological details and especially the presence of generalized indolent lymphadenopathy, the diagnosis of secondary syphilis was made. Although plaques opalines are a relatively rare manifestation of secondary syphilis, they can occasionally be the only sign and are important in the differential diagnostic considerations of gray-white mucosal lesions, especially with current continuing rise of syphilis incidence in Central Europe.