Angiosarcoma

Angiosarcomas (AS) are very rare malignant tumors (< 1% of all sarcomas) that exhibit both the function and morphology of endothelial cells. They are very diverse and vary from very well-differentiated angiosarcomas, which are initially difficult to distinguish from other vascular tumors, to highly malignant, low-differentiated angiosarcomas. In childhood, angiosarcomas only occur very rarely. However, when they do occur in children, they differ from adult angiosarcomas. For example, they are more likely to manifest in internal organs and are associated with other diseases. Typical localizations for angiosarcomas are the skin (about 50%), the breast, soft tissue, the heart or even the bones.

Angiosarcomas are divided into different clinical groups:

• Primary cutaneous angiosarcoma (without association to lymphedema or radiation exposure)
• Lymphedema-associated angiosarcoma
• Post-radiation angiosarcoma
• Angiosarcoma of deep soft tissue
• Angiosarcoma of parenchymatous organs (bone, liver, spleen, heart, breast)

Some etiologic factors can already be deduced from this. Chronic lymphedema and radiation are the best known predisposing factors for angiosarcoma. Typically, lymphedema-associated angiosarcomas develop in women who have undergone a radical mastectomy and axilla dissection for breast cancer, as a result of which chronic lymphedema has developed. The exact relationship between lymphedema and angiosarcoma has not yet been conclusively clarified.

Radiation-associated angiosarcomas develop with a latency period of several years (usually > 10 years) after irradiation inside the area of former irradiation.

Primary cutaneous angiosarcomas represent the largest group, accounting for nearly half of all angiosarcomas. They typically occur from the 7th decade of life onwards, with an equal frequency in men and women. Half of these angiosarcomas develop in the head and neck area, especially on the scalp and forehead – an association with sunlight has been repeatedly debated, but sun exposure seems to have no influence on the development of angiosarcomas. The clinical picture here is very variable: in addition to lesions that are only slightly raised and difficult to delineate,  raised, nodular and occasionally ulcerated masses may be noticeable. Angiosarcomas are often not diagnosed until advanced stages because of the varied, often harmless-looking macroscopic clinical findings.

Most angiosarcomas are moderately differentiated and show blood vessel structures of irregular size and shape. The endothelial cells are particularly conspicuous, some of which are significantly enlarged and show atypical features. Immunohistochemically, angiosarcomas are positive for ERG, CD34, CD31 and Fli1.

The 5-year survival of patients with primary cutaneous angiosarcoma is 30–50%. The outcome depends on various factors such as patient age, angiosarcoma size and resection status.