Case of juxta-articular osteoid osteoma of calcaneus mimicking arthritis.

Juxta-articular osteoid osteoma is a rare disorder that is difficult to correctly diagnose at an early stage. We report a case of osteoid osteoma in the calcaneus that arose near to the talocalcaneal joint. An 18-year-old female presented with symptoms of joint swelling and effusion similar to those of monoarthritis. Conservative treatment proved ineffective in achieving pain relief, and she underwent surgery 6 months later. The lesion was diagnosed by histologic examination, and it resolved after resection of the tumor.