Bizarre parosteal osteochondromatous proliferation
| Bizarre parosteal osteochondromatous proliferation | |
|---|---|
| Other names | Nora lesion or Nora disease |
| Specialty | Orthopedics |
| Symptoms | Painless lump in finger or toe |
| Risk factors | Possibly trauma in a minority |
| Diagnostic method | Medical imaging |
| Differential diagnosis | Mainly subungal exostosis |
| Treatment | Surgical excision. |
| Prognosis | Up to 50% recur after surgery |
| Frequency | Rare, <5% of cartilage tumors, M=F |
Bizarre parosteal osteochondromatous proliferation (BPOP), also known as Nora's lesion, is a type of non-cancerous bone tumor belonging to the group of cartilage tumors. It is generally seen in the tubular bones of the hands and feet, where it presents with a rapidly enlarging lump in a finger or toe which may be painful while growing.
It is composed of bone, cartilage and spindle cells. Some people report previous trauma.
Diagnosis is by medical imaging. Treatment is by surgical excision. Up to 50% recur after surgery.
It is rare, and occurs more often in the 20s and 30s. Combined with subungal exostosis, it accounts for less than 5% of cartilage tumors. Males and females are affected equally. The condition was first described by Frederick E. Nora in 1983.