DIAGNOSIS Cerebral angiosarcoma.
Angiosarcoma is a rare tumor accounting for less than one percent of all sarcomas (15). It occurs typically in the skin and soft tissues of the head and neck. It is a very malignant neoplastic proliferation arising from vascular endothelial cells. Systemic metastasis at the time of diagnosis is reported to be as high as 80% (8). Central nervous system (CNS) involvement has been described, but is quite unusual. Only 17 cases of cerebral angiosarcoma primary to the CNS have been reported in the English literature (9, 10). It occurs principally in the cerebral hemisphere with a predisposition for the parietal lobe. The mean age at diagnosis is 38 years and it shows a slight male predominance (66.7%). Cerebral metastases are also rare; only 21 cases have been described (1,3,5,6,8,9,11,14). The typical primary site for metastatic cerebral angiosarcoma is the heart, accounting for 57% of cases. Other primary sites have been described, such as Dacron aortic vascular grafts, aorta, pleura, skin, liver, penis, bone, placenta and the orbit. Cerebral metastases are multiple in 57.9% of the cases. There is a male predominance and the mean age is 42.2 years. The described risk factors for the development of angiosarcomas are radiation therapy, foreign object (12), chronic lymphedema associated with radical mastectomy, A-V fistulas and certain environmental carcinogens like vinyl chloride, arsenic and Thorotrast.
In a series of 53 post-radiation sarcomas (7), Laskin and al. reported that the most frequent radiation-induced sarcoma was malignant fibrous histiocytoma (68%) and that an angiosarcoma represented only one case (2%), on the thoracic wall. Another series (13) of 2500 patients treated for ENT cancer reported only 5 sarcomas in the irradiated zone. None were angiosarcoma.
Vascular prostheses, especially Dacron prostheses, also have the potential to induce malignant mesenchymatous changes (2,4,11,16). We, however, did not find any cases that occurred after insertion of a vascular endoprosthesis.
The histologic examination of this case shows typical features of angiosarcoma: atypical cells forming an irregular vascular network. The positivity of these cells for endothelial markers confirms the diagnosis. Immunohistochemistry for factor VIII was slightly positive but cases with poorly differentiated tumors are reported with equivocal positivity for this marker.
We believe this patient had an angiosarcoma of the carotid artery with distal tumor embolisms since all the lesions were restricted to this vascular territory, and presented as stroke-like episodes. The carotid stent might have contributed to the development of the tumor in tissues already sensitized by the prior irradiation. The brain tumors may also be primary angiosarcomas, but in view of the multiplicity of the lesions and the restriction to the vascular territory of the left internal carotid artery, this hypothesis seems less likely. Investigations did not reveal any other possible primary source. Unfortunately, even though a mass of tumoral cells was identified inside one of the specimen's vascular channels, we are not able to ascertain that the primary site is the carotid artery, as the family of the patient refused the proposed autopsy.
Contributed by Nicolas Dea MD; Manuela Pelmus MD; David Mathieu MD; François Belzile MD; Denis Bergeron MD; Sylvie Gosselin MD; Ana-Maria Tsanaclis MD