title: Low-grade intraosseous osteosarcoma in northern Japan: advantage of AgNOR and MIB-1 staining in differential diagnosis.
abstract: Low-grade intraosseous osteosarcoma is an uncommon form of bone cancer. It is occasionally difficult to recognize as a malignant tumor and is commonly misdiagnosed as a benign fibrous lesion. We retrospectively studied the records of 8 patients with low-grade intraosseous osteosarcoma in the files of the Tohoku Musculoskeletal Tumor Society in Japan. All tumors arose in the lower limb. The most common symptom was pain, with a duration exceeding 2 years in 4 patients. Radiologic findings, including those at magnetic resonance imaging (MRI), suggested malignancy in 5 lesions, whereas 3 were diagnosed as benign. Two patients initially presented with pathological fracture. The initial pathological diagnosis was malignant in 5 patients and benign in 3. All eight tumors were grade 1 in Broders' classification. The tumor showed a permeative pattern in all eight cases, but this pattern could not be confirmed in the multiple tiny fragments obtained as biopsy specimens in 3 cases. The number of silver-staining nucleolar organizer regions (AgNOR) per nucleus and MIB-1-positive rate were significantly higher in low-grade intraosseous osteosarcoma than in fibrous dysplasia, offering an advantage in differential diagnosis. Three patients (38%) developed high-grade sarcoma at the site of local recurrence after multiple intralesional excisions, and one of them died of the disease. The other 5 patients had a good clinical course after surgery with a wide margin. These findings indicate that preoperative diagnosis with radiologic investigation, including magnetic resonance (MR) imaging and histologic examination of biopsy specimens is essential in preparation for surgery with a wide margin, assuring a good clinical course, and the results of AgNOR and immunohistochemical MIB-1 staining might be helpful in differentiating low-grade intraosseous osteosarcoma from fibrous dysplasia.
authors.affiliation: Tohoku Musculoskeletal Tumor Society, Akita University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Okada
authors.forename: J
authors.initials: J
authors.lastname: Nishida
authors.forename: T
authors.initials: T
authors.lastname: Morita
authors.forename: H
authors.initials: H
authors.lastname: Kakizaki
authors.forename: A
authors.initials: A
authors.lastname: Ishikawa
authors.forename: T
authors.initials: T
authors.lastname: Hotta
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D034961:Antigens, Nuclear; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D003131:Combined Modality Therapy; D003937:Diagnosis, Differential; D005260:Female; D005266:Femoral Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D007564:Japan; D019394:Ki-67 Antigen; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000032:analysis*; D009697:Nucleolus Organizer Region / Q000473:pathology*; D012516:Osteosarcoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D011859:Radiography; D016622:Silver Staining
chemical_list: D034961:Antigens, Nuclear; D019394:Ki-67 Antigen; D009687:Nuclear Proteins