We report a 59 years old man with a suspicious sexual contact between 3-5 years ago, who developed repeated painless swelling in his left knee, and a progressive destructive osteitis in his tibia. After rejecting other pathologies, the diagnosis arrived by the high treponemic activity proved by specific serology and the clinical recovery with antibiotic treatment. The swelling disappeared and only the residual deformity persisted. We didn't find any treponema in the biopsy.... [Leer más...]