title: A bizarre parosteal osteochondromatous proliferation (Nora's lesion) of metatarsus, a histopathological and etiological puzzlement.
abstract: Nora's lesion (bizarre parosteal osteochondromatous proliferation) is a rare, benign lesion that is composed of differing amounts of cartilage, bone, and spindle cells and an unusual form of calcified cartilage so-called "blue bone". Whether it represents a reactive proliferation or a neoplastic lesion still remains controversial. We present a 24-year-old woman having a 4.5cm two lobulated mass attached to second metatarsus of her left foot. The lesion was hyperintense on magnetic resonance imaging and accompanied by an extensive soft tissue and bone marrow edema. In resection specimen, smaller lobule appeared stuck-on the cortex while the larger one had a broader base and a 0.4cm cartilaginous cap-like formation. The histological picture was best fit to Nora's lesion however showed less fibroblastic tissue and cartilaginous pleomorphism. The lesion also showed areas with cortical invasion and a small focus of fracture callus accompanied by adjacent medullary edema and fat necrosis. The case is presented with the comparative radiologic, macroscopic and microscopic findings for its diagnostic difficulties and etiopathogenetic considerations in favour of a maturation phenomenon in parosteal ostecartilaginous lesions irrespective of the cause.
authors.affiliation: Ege University Faculty of Medicine, Department of Pathology, Izmir, Turkey. Electronic address: bdoganavsargil@yahoo.com.
authors.forename: Basak
authors.initials: B
authors.lastname: Doganavsargil
authors.affiliation: Ege University Faculty of Medicine, Department of Radiodiagnostics, Izmir, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Argin
authors.affiliation: Ege University Faculty of Medicine, Department of Pathology, Izmir, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Sezak
authors.affiliation: Ege University Faculty of Medicine, Department of Orthopedics, Izmir, Turkey.
authors.forename: Burcin
authors.initials: B
authors.lastname: Kececi
authors.affiliation: Ege University Faculty of Medicine, Department of Pathology, Izmir, Turkey.
authors.forename: Burcin
authors.initials: B
authors.lastname: Pehlivanoglu
authors.affiliation: Ege University Faculty of Medicine, Department of Pathology, Izmir, Turkey.
authors.forename: Fikri
authors.initials: F
authors.lastname: Oztop
mesh_terms: D001859:Bone Neoplasms / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D006801:Humans; D008684:Metatarsus; D015831:Osteochondroma / Q000175:diagnosis* / Q000209:etiology; D055815:Young Adult
keywords: Bizarre parosteal osteochondromatous proliferation; Foot; Pathogenesis; Radiographs