Osteoblastic extraskeletal osteosarcoma: the most common variant the tumor cells resemble malignant osteoblasts. In contrast to myositis ossificans the bone is usually most prominent in the centre of the tumor. Common to all variants is the presence of neoplastic bone deposited in a lacy, trabecular or sheet-like pattern. The tumor cells are spindle or polyhedral with cytological atypia, malignant chondroid areas, extensive areas of necrosis, mitotic activity (>10 mitoses per 10 high-power fields), and atypical mitotic figures.Īll the major subtypes of osteosarcoma of bone have been reported in extraskeletal osteosarcoma. Micro pathology: Extraskeletal osteosarcoma is characterized by anaplastic sprindle cell proliferation with the presence of osteoid matrix or immature bone formed by the neoplastic cells.
The tumor has a remarkable ability to infiltrate the surrounding tissues occasionally it can be confined to the subcutis or dermis, or ulcerate the overlying skin. A tough connective tissue capsule usually surrounds the tumors and adheres to the surrounding structures, making dissection difficult. Most extraskeletal osteosarcomas are deep seated 30% appear grossly encapsulated, and >10% may exhibit extensive haemorrhagic cystic changes. The reported male to female ratio is 1.9:1. It typically affects patients between 50 and 70 years of age. Response to treatments (mainly chemotherapy) is worse and prognosis is much poorer compared to that for primary osteosarcoma of bone.Įxtraskeletal osteosarcoma accounts for 1% to 2% of all soft tissue sarcomas and approximately 2% to 4% of all osteosarcomas. Often it arises at the site of prior radiation therapy. In contrast to the more common osteogenic sarcoma (osteosarcoma), extraskeletal osteosarcoma is a rare tumor occurring mainly in adults. For a lesion to be defined as extraskeletal osteosarcoma, it must arise in the soft tissue and not attached to bone or periosteum, have a uniform sarcomatous pattern, and produce osteoid and/or cartilage matrix. (Note : for Links provided by Atlas : click)Ĭ470-C476,C478-C479,C490-C496,C498-C499 CONNECTIVE & SOFT TISSUEĮxtraskeletal osteosarcoma is a high-grade malignant mesenchymal soft tissue neoplasm composed of neoplastic cells (osteoblastic, chondroblastic and fibroblastic) that produce osteoid, neoplastic bone or chondroid matrix and has a clinically aggressive course. X Y 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 NA Soft Tissues: Extraskeletal osteosarcoma WrittenĪndreas F Mavrogenis, Panayiotis J Papagelopoulosįirst Department of Orthopaedics, Athens University Medical School, 41 Ventouri Street, 15562 Holargos, Athens, Greece Home Genes Leukemias Solid Tumors Cancer-Prone Deep Insight Case Reports Journals Portal Teaching Soft Tissues: Extraskeletal osteosarcoma Atlas of Genetics and Cytogenetics in Oncology and Haematology