Primary vascular tumors of the vertebral bones are extremely unusual1, comprising <1% of all bone neoplasms1, 2. Their diagnosis is often challenging because of their clinical presentations vary from totally asymptomatic to extremely aggressive2. Another problem associated with these tumors is the great confusion around their terminology; this problem has been resolved with the restriction of the term “hemangioendothelioma” to soft tissue lesions with a low degree of malignancy only1, 3. The term “epithelioid hemangioendothelioma”, which was first introduced by Weiss and Enzinger to denote a group of soft tissue tumors, has been used many times since to incorrectly categorize bone tumors1. The correct pathological diagnosis of these neoplasms is a priority because it is essential to the rapid selection of an effective management plan. We here describe a case of a primary vertebral angiosarcoma and present a concise review of the more relevant diagnostic aspects. A 69-year-old woman presented with a 3-year history of lower extremity paresthesiae at the T10 level that limited her ability to walk. Previous cervical and lumbar MRI and dorso-lumbar radiographs had shown degenerative changes without any evidence of fractures or invasive lesions of the spinal cord. On physical examination, the patient had mild palpebral ptosis with facial symmetry. In addition, she had spasticity in both legs and decreased T12 level sensation. No other clinical neurological manifestations were found. Vertebral MRI showed reduced height and low intensity on the T1 sequence and mild hyperintensity of the T11 vertebral body on the T2 sequence. A short time inversion recovery contrasted sequence showed increasing signal intensity. The vertebral lesion involved adjacent soft tissues and dura mater, compressing the spinal medulla to the right and posterior aspect of the spinal canal at the T10 level and involving 80% of the canal at T11 (Fig. 1). MR Images showing (a) T1 low intensity signals in the vertebral bodies of T8 and T11 with (b, c) hyper-intensity in the T2 and STIR sequences in sagittal views. (d) MRI showing multiple lesions between T5 and L1 in bone window. (e and f) These lesions were biopsied under CT guidance, posterior wall rupture with spinal canal compromise and rejection/compression of the medulla cord is visible. A vertebral bone biopsy was performed. Histopathological examination showed a vascular neoplasm characterized by a proliferation of endothelial cells with atypical nuclei distributed in anastomosed intra-trabecular channels filled with abundant erythrocytes (Fig. 2). The endothelial cells were positive for Friend leukemia integration 1 transcription factor (FLI-1), cluster of differentiation (CD) 34 and CD31 and negative for CD10, osteopontin, epithelial membrane antigen, cytokeratin (CK) 7, CK20 and AE1/AE3 (Fig. 2). A primary angiosarcoma of the vertebral body was diagnosed. Histopathological examination showed a malignant neoplastic lesion composed of a vast quantity of anastomosing vascular channels with atypical prominent endothelium that contained erythrocytes and invaded adjacent bone structures (HE, a: ×10, b and c: ×40). The neoplastic cells were positive for (d) CD34 (×4), (e) CD31 (×40) and (f) FLl-1 (×40), and negative for (g) AE1/AE3 (×4). The patient received palliative care and died 2 months later. Because bone vascular lesions can be reactive processes or benign or malignant (highly aggressive) neoplasms4, the terminology used to describe these tumors is variable. In 1943, Stout first described a case of vascular tumor of bone and denoted it as “hemangioendothelioma”1. Later on, with discovery of the wide behavioral spectrum of those neoplasms, they have been classified as both benign and malignant tumors, the latter being variously called angiosarcomas, angioendotheliomas, hemangioendotheliomas, hemangioendothelial sarcomas, hemangiosarcomas or anaplasic vascular tumors. These capricious terminologies have been used because of the variability in their clinical and morphological features, which are a product of their complex and irregular architecture combined with a high degree of pleomorphism and cellular atypia3, 4. Some authors have suggested that the ones that behave innocuously are really bone hemangiomas (the most common bone tumor, with an autopsy prevalence around 10.7% in the general population, although many cases diagnosed as hemangiomas are actually vascular malformations)2, 3. Angiosarcomas are malignant vascular neoplasms with endothelial cell differentiation3, 4 and atypical features such as polyhedral and fusiform cytology. On clinical evaluation, the most distinctive characteristic of bone angiosarcomas is the presence of multiple lesions in the same bone: solitary multifocal multicentric lesions (1/3 of all cases)5; such as were visible in our case (Fig. 1). Another typical feature is that the mass is highly destructive with poorly defined margins2, 5, 6. Bone angiosarcomas occur more often in men than women, at an average age of 62 years (range, 26–83 years) and average 5 cms in diameter6, 7. Previous exposure of affected subjects to external factors such as radiation, thorotrast and polyvinyl chloride has been described8. No such exposure had occurred in our case. Macroscopically, these neoplasms are soft and hemorrhagic. Histopathological examination shows neoplasms with highly complex architecture composed mainly of anastomosing vascular cords bounded by atypical endothelial cells and showing alveolar or pseudo-glandular formations. Desmoplastic reactions and papillary formations are also sometimes found in bone angiosarcomas. Furthermore, trabecular osteoid with osteoclastic activity typical of bone neoformation is frequently seen1, 3, 4. The endothelial cells within angiosarcomas can resemble the malignant cells observed in epithelial neoplasms; for this reason, they are called “epithelioid”)3, 5. Because of this last, epithelial neoplasm is a frequent differential diagnosis. Other entities that can be confused with bone angiosarcomas are fusiform sarcomas. These possibilities can be excluded by immunohistochemical staining: angiosarcomas are characteristically positive for CD34, CD31, FLI-1, factor VIII, thrombomodulin and Ulex europaeus agglutinin 1 and have a high proliferation (Ki67) index. In our case, because the disease presented at such an advanced stage, it was impossible to provide any curative therapeutic strategy. In these highly aggressive tumors, the initial treatment of choice is total en bloc resection. Because this approach minimizes intralesional invasion, it is also recommended for primary malignant spine tumors in instances where the expected surgical margin is definitive9. However, recurrence after resection is very common and the prognosis notoriously poor because metastases tend to develop early1. Metastases to the lungs and other parenchymal organs are found in about 66% of cases. Radiotherapy is effective for local control of the disease in some patients and in others offers dramatic palliative benefits. Angiosarcomas can disseminate to surrounding tissues or, frequently, to extra-osseous sites. Chemotherapy regimens offer variable results in such cases and the ideal combination remains undefined1, 2, 10. Chemotherapy regimens, including cisplatin with doxorubicin, cisplatin plus paclitaxel and cisplatin plus doxorubicin and paclitaxel, have been studied10. However, prolonged responses are very uncommon and better therapies are urgently needed9, 10.