Bizarre parosteal osteochondromatous proliferation (Nora lesion) involving the spine: a case report and systematic review.

Bizarre parosteal osteochondromatous proliferation (BPOP), also termed Nora lesion, is a rare, benign tumor most often located in the hands and feet. We herein present the second reported case of BPOP affecting the spine, an uncommon location. One year after surgical excision, the patient was pain-free and showed no evidence of recurrence. We reviewed a total of 323 cases of BPOP among 101 articles, providing the first systematic update on the latest knowledge of BPOP. The age of patients with BPOP ranges from 3 months to 87 years, peaking in the second and third decades of life. The hands are the most common location of BPOP (58.39%), followed by the feet (20.81%). Imaging features play a key role in the diagnosis of BPOP, but histopathologic diagnosis remains the gold standard. Differential diagnosis of BPOP should be based on the epidemiologic and clinical features as well as clinical examination findings. Surgical resection is the most extensively used treatment for BPOP. Recurrence is common (37.44%) and can be treated with re-excision. This article can deepen our understanding of BPOP and will be helpful for the diagnosis and treatment of BPOP in clinical practice.