title: [Pathomorphology of parosteal osteosarcoma. Experience with 125 cases in the Hamburg Register of Bone Tumors].
abstract: Parosteal osteosarcoma is a rare low-grade bone tumor. It occurs between the 2nd and 8th decade of life. In our own series of 125 parosteal osteosarcomas, most patients were aged between 30 and 40. The most frequent location was the distal dorsal femur. Until clearly proven otherwise, a bone-forming tumor in this location has to be regarded as a parosteal osteosarcoma. Of all parosteal osteosarcomas 77% are located in the lower extremity, with a female sex predominance in this location (62%); 18% are located in the upper extremity; 15% of all parosteal osteosarcomas are located in the humerus. Just 6% of all parosteal osteosarcomas are observed in the skull, the spine, and the pelvis. The tumor is characterized by hyalinized fibrous stroma with a low cell content without substantial nucleus polymorphism and variably dense bony trabeculae. The diagnosis can be difficult due to highly differentiated areas with fat tissue within the marrow and very uniformly bony structure. The operation material has to be analyzed very carefully, because the extent of dedifferentiated areas and most probably also the extent of invasion of the medullary cavity determine the prognosis and occurrence of recurrencies. The tumor is most commonly misinterpreted as osteochondroma or heterotopic ossification. Paying attention to all radiologic and histologic criteria,osteoblastic eccentrically located high-grade osteosarcomas can be clearly distinguished from parosteal osteosarcoma. An intramedullary located low-grade osteosarcoma,which is differentiated like a parosteal osteosarcoma,is histologically indistinguishable from the parosteal variant. This variant requires the synthesis of all available data to find the correct diagnosis. The parosteal osteosarcoma shows like no other tumor the necessity of close cooperation of all involved disciplines for diagnosis and therapy.
authors.affiliation: Abteilung Osteopathologie, Pathologisches Institut, Universität Hamburg. delling@uke.uni-hamburg.de
authors.forename: G
authors.initials: G
authors.lastname: Delling
authors.forename: M
authors.initials: M
authors.lastname: Werner
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019046:Bone Marrow Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D001842:Bone and Bones / Q000473:pathology; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D002648:Child; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D005260:Female; D005266:Femoral Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018217:Osteosarcoma, Juxtacortical / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D011379:Prognosis; D012737:Sex Factors