Bizarre parosteal osteochondromatous proliferation (Nora’s lesion) of the talus: a case report

Introduction: Bizarre Parosteal Osteochondromatous Proliferation (BPOP), or Nora’s Lesion, is a very rare condition, with less than 200 documented cases that exist in the literature. BPOP / Nora’s Lesion of the talus has not been reported in any literature in Indonesia. Therefore, this study aim to present a unique and rare case of BPOP (Nora’s Lesion) of the talus. Case: An eighteen-year-old male patient admitted to hospital with a complaint of palpable lump at his front right ankle region since seven years ago with the size of a marble. On physical examination, there was a swelling of the anteromedial aspect of the ankle, hard in consistency, well-defined, immobile, and without neurovascular impairment. There was pain exacerbated by sports activities. There was a history of trauma at the located lump; he was fell while running on the ground a few years before the lump first arose with no fracture, wound, or swelling at that area. The range of motion (ROM) of the right ankle was less than the left ankle. The operation was performed under general anesthesia. After an incision was made, the mass was exposed and we did an osteotomy and a complete surgical excision. Conclusion: In this case, the radiographic imaging showed well-defined exostosis arising from the anteromedial aspect of the talus bone cortex, but not in continuity with it. Histopathological examination consistent with BPOP. We suggest a surgical “En-bloc” (complete surgical excision) as a recommended treatment for BPOP.