title: [Unusual parosteal osteochondromatous proliferation or Nora's tumor. A clinicopathological analysis of 4 cases].
abstract: Nora's lesion, also known as bizarre parosteal osteochondromatous proliferation (B.P.O.P.), involves mostly the small tubular bones of the hands and feet. Histologically, it is characterized by a proliferation of chondroid, bony and fibrous tissues, sometimes with high cellular density, bizarre chondrocytes but is devoid of cellular atypia and necrosis. Distinct blue color is noted at the interface of bone and cartilage. The most important lesions that present differential diagnostic problems are chondrosarcoma, parosteal osteosarcoma and florid reactive periostitis. The lesion is benign but may recur locally in as many as 55%. The clinical and pathological findings of four cases of Nora's lesion are presented.
authors.affiliation: Service d'Anatomie et de Cytologie Pathologiques, Hôpital Bichat, 75018 Paris, France.
authors.forename: Valère
authors.initials: V
authors.lastname: Claude
authors.forename: Christian
authors.initials: C
authors.lastname: Couture
authors.forename: Régine
authors.initials: R
authors.lastname: Battin-Bertho
authors.forename: Maggy
authors.initials: M
authors.lastname: Grossin
authors.forename: Réal
authors.initials: R
authors.lastname: Lagace
authors.forename: Dominique
authors.initials: D
authors.lastname: Hénin
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000473:pathology*; D002455:Cell Division; D005385:Fingers; D005529:Foot Bones; D006801:Humans; D008297:Male; D015831:Osteochondroma / Q000473:pathology*