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WHO Classification of Tumours
Osteosarcoma, NOS


A usually aggressive malignant bone-forming mesenchymal tumour, predominantly affecting adolescents and young adults. It usually involves bones and less frequently extraosseous sites. It often involves the long bones (particularly distal femur, proximal tibia, and proximal humerus). Pain with or without a palpable mass is the most frequent clinical symptom
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Fletcher CDM, Unni KK, Mertens F (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of Soft Tissue and Bone.
3rd Edition
IARC Press: Lyon 2002


Pure osteosarcomas account for approximately 12% of all mammary sarcomas. They arise in adults over a wide age range (median age 64.5 years); most patients are women

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Silver SA, Tavassoli FA (1998)
Primary osteogenic sarcoma of the breast: a clinicopathologic analysis of 50 cases.
Am J Surg Pathol 22: 925-33

. The tumour presents as an enlarging, well circumscribed mass measuring 1.4 to 13 cm. It may be associated with pain, bloody nipple discharge or nipple retraction. There is focal to extensive calcification. In larger tumours, cavitation and necrosis can be observed. Histologically, the tumour is composed of spindled to oval cells that produce osteoid and/or bone; cartilage is found in >1/3 of cases. There is no connection to the skeleton.
Mammary osteosarcomas are highly aggressive. The overall five-year survival rate is 38%. The tumour recurs in more than two-thirds of cases treated by local excision, and in 11% of cases treated by mastectomy. Osteosarcomas metastasize most frequently to the lungs. Axillary nodes are typically not involved. Factors worsening the prognosis are large tumour size at presentation, prominent infiltrating margins, and necrosis

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Tavassoli FA, Devilee P (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of the Breast and Female Genital Organs.
3rd Edition
IARC Press: Lyon 2003