High-grade angiosarcomas (HGAS) of bone are rare and represent less than 1% of the primary malignant bone tumours. Because of their rareness little is known. Clinically, it is accepted that they are extremely aggressive. Due to the lack of uniform terminology and accepted histological criteria, terminology and classification of primary malignant vascular tumours of bone has been highly controversial. Today, angiosarcoma is the most accepted term for high-grade primary vascular tumour of bone, recognized by the 2002 WHO Classification. However, distinct histological hallmarks to define a HGAS of bone are not clear.

We collected 64 HGAS of bone diagnosed between 1964 and 2007 from the files of the departments of pathology, Leiden University Medical Center (Leiden), Rizzoli Institute (Bologna) and University Hospitals (Leuven). All clinical, radiological, and pathological data were reviewed and different histological criteria were scored. A tissue micro-array was constructed containing 57 HGAS of bone. To confirm the vascular origin of all lesions and to investigate the diagnostic value of commonly used markers, immunohistochemistry was performed for CD31, CD34, Factor VIII, and keratin AE1/AE3. Staining was evaluated positive or negative.

Among 64 patients with HGAS of bone, there are 41 males and 23 females. There is a wide age distribution, with a nearly equal distribution from the second to the sixth decade. The solitary cases are mostly located in the extremities (66%) followed by trunk (12.8%), axial/central location (10.6%) and pelvis (10.6%). 17 cases (73%) have multifocal bone lesions. HGAS of bone show variable histological patterns. Association with clinical outcome (chi-square test) reveals that there is a significant poor survival when the tumour has tree or more mitoses (p=0.001), a macronucleoli (p=0.011) or there is an absence of an eosinophilic infiltrate (p=0.023). The HGAS of bone are positive for CD31 in 53/55 (96%), CD34 in 33/57 (58%), Factor VIII in 47/55 (86%), and keratin in 40/57 (70%). Only 15 out of 40 (38%) keratin positive angiosarcomas, showed an epithelioid phenotype at classical morphology. All tumours with an epithelioid phenotype are keratin positive.

Although HGAS of bone in general have a poor outcome, histological criteria such as three or more mitoses, the presence of a macronucleolus and the absence of an eosinophilic infiltrate can be useful to predict a more aggressive course, consistent with the clinical behaviour of a high-grade angiosarcoma. CD31 and Factor VIII are the best diagnostic markers for HGAS of bone. It is striking that keratin positivity is seen in the majority of cases, and is independent of epithelioid morphology. Pathologists should be aware of this to avoid misinterpretation as metastatic carcinoma.

Ollier disease is a rare skeletal disorder. It is characterized by the occurrence of multiple enchondromas with a marked unilateral predominance mainly affecting medulla of the metaphyses and diaphyses of the short and long tubular bones of the limbs, especially the hands and feet. The risk of malignant transformation is suggested to be up to 35%. We hypothesise that Ollier disease is a mosaic condition as it is polyostotic and because of its unilateral predominance. Here we aimed to identify molecular defects in Ollier disease related enchondromas and chondrosarcomas using high resolution single nucleotide polymorphism (SNP) array approach. Affymetrix SNP 6.0 was performed on 67 samples which include 10 blood samples and 3 matched blood-saliva samples as a control; 13 enchondromas and 26 chondrosarcomas of different grades from 30 Ollier patients and normal DNA from 12 Ollier patients for paired comparison.

All samples were divided into three groups: normals, enchondromas and chondrosarcomas. The number of numerical genomic changes in the chromosomes were not different for the enchondromas (p=0.36) while large genomic aberrations were seen in chondrosarcomas as compared to normals (p=0.01). Copy number variation (CNV) analysis showed 95K amplification at 4q13 in 5 out of 13 enchondromas and a 2K deletion at 14q11 in 6 out of 13 enchondromas. Paired loss of heterozygosity (LOH) analysis failed to show LOH in 5 enchondromas at higher resolution. Paired LOH was observed at 3q, 5p, 6p, 6q, 7q, 9p, 12p, 13p and 13q in 7 high grade chondrosarcomas associated with loss of chromosomes.

The results of this study indicate involvement of chromosomes 4 and 14 for the development of enchondromas. We were unable to detect LOH in enchondromas at 1Mb resolution containing approximately 500 SNP probes. High grade chondrosarcomas showed LOH at different chromosomes. In future, we will study LOH and CNV changes at gene level and select candidate genes.