Pseudoanaplastic tumors of bone.
OBJECTIVE
To discuss the concept of pseudoanaplastic tumors of bone, which pathologically show hyperchromatism and marked pleomorphism with quite enlarged, pleomorphic nuclei, but with no to extremely rare, typical mitoses, and to propose guidelines for their diagnosis.


METHODS
From a database of 4,262 bone tumors covering from 1971 to 2001, 15 cases of pseudoanaplastic bone tumors (0.35% of total) were retrieved for clinical, radiographic and pathologic review. Postoperative follow-up after surgical treatment was at least 3 years and a maximum of 7 years.


RESULTS
There were eight male and seven female patients. Their ages ranged from 10 to 64 years with average of 29.7 years. Pathologic diagnoses of pseudoanaplastic variants of benign bone tumors included: osteoblastoma (4 cases), giant cell tumor (4 cases), chondromyxoid fibroma (3 cases), fibrous dysplasia (2 cases), fibrous cortical defect (1 case) and aneurysmal bone cyst (1 case). Radiography of all cases showed features of a benign bone lesion. Six cases, one case each of osteoblastoma, fibrous dysplasia, aneurysmal bone cyst, chondromyxoid fibroma, giant cell tumor and osteoblastoma, were initially misdiagnosed as osteosarcoma. The remaining cases were referred for a second opinion to rule out sarcoma.


CONCLUSIONS
Despite the presence of significant cytologic aberrations, none of our cases showed malignant behavior following simple curettage or removal of bony lesions. Our observation justifies the concept of pseudoanaplasia in some benign bone tumors as in benign soft tissue tumors, especially in their late evolutionary stage when bizarre cytologic alterations strongly mimic a sarcoma.
Bahk
Won-Jong
WJ
Department of Orthopaedic Surgery, Uijongbu St. Mary Hospital, The Catholic University of Korea, 65-1 Geumohdong, Uijongbu, Gyunggido, 480-821, Korea. wjbahk@cmc.cuk.ac.kr
Mirra
Joseph M
JM
D000293:Adolescent; D000328:Adult; D000708:Anaplasia / Q000175:diagnosis; D017824:Bone Cysts, Aneurysmal / Q000000981:diagnostic imaging / Q000473:pathology; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D002648:Child; D003951:Diagnostic Errors; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology; D005357:Fibrous Dysplasia of Bone / Q000000981:diagnostic imaging / Q000473:pathology; D005500:Follow-Up Studies; D005870:Giant Cell Tumors / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging / Q000473:pathology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging / Q000473:pathology; D018215:Osteoblastoma / Q000000981:diagnostic imaging / Q000473:pathology; D012516:Osteosarcoma / Q000000981:diagnostic imaging / Q000473:pathology; D015641:Radiography, Interventional; D012189:Retrospective Studies; D012447:Sacrum / Q000000981:diagnostic imaging / Q000473:pathology