Distinct histological features characterize primary angiosarcoma of bone

Aims: To define the histological criteria of primary angiosarcoma of bone. Methods and results: Forty-two angiosarcomas of bone in 23 males and 15 females were studied. Histological criteria were related to patients' outcome. Eleven patients had multifocal lesions. Lesions were located in the long and short tubular bones followed by the pelvis, spine and trunk. Tumour cells were positive for CD31 in 38 of 40, von Willebrand Factor in 21 of 35, CD34 in 15 of 38, smooth muscle actin in 22 of 36, D2-40 in 11 of 35 and keratinAE1AE3 in 27 of 39. Thirty-nine tumours showed an epithelioid phenotype. One- and 5-year survival rates were 55% and 33%, respectively. Survival analysis showed that a macronucleolus, three or more mitoses per 10 high-power field (HPF) and fewer than five eosinophilic granulocytes per 10 HPF within a tumour was associated with an even worse survival compared to the overall group. Conclusions: Because keratin positivity is seen in the majority of cases, pathologists should avoid misinterpretation as metastatic carcinoma. A macronucleolus, three or more mitoses per 10 HPF and fewer than five eosinophilic granulocytes per 10 HPF can be used to further define angiosarcoma of bone.