Angiosarcoma Pathology

Updated: Nov 18, 2013
  • Author: Francis H Gannon, MD; Chief Editor: Francis H Gannon, MD  more...
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Angiosarcoma is a rare sarcoma of intraosseous endothelial cells. [1] The etiology for primary angiosarcoma lesions is unknown; however, they have been reported following radiation therapy. [2]

Although this tumor is also known as a hemangiosarcoma, hemangioendothelial sarcoma, and malignant hemangioendothelioma, these secondary terms should be avoided to prevent confusion with epithelioid hemangioendothelioma, which is a separate entity.

Angiosarcomas of bone are very rare and account for less than 1% of all angiosarcomas in any organ and less than 1% of primary bone tumors. [1, 2] Although patients with these tumors range in age from 12 to 74 years, most patients are in their 30s or older; angiosarcomas are generally rare before then. [2] Males are more commonly affected than females in a ratio of approximately 2 to 1.

En bloc excision or amputation is the therapy of choice for angiosarcomas. [3] Curettage is inevitably followed by local recurrence, [4, 5] and metastases are common. [4] The effects of radiation therapy and chemotherapy have not been adequately assessed. [2]

The outlook for skeletal angiosarcoma is poor. The 5-year survival rate has been reported to be between 10% and 30% in various studies. [1, 3]

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Clinical Features and Imaging

Pain is the usual presenting symptom.

Angiosarcomas produce lytic lesions with ill-defined borders and destructive patterns on radiologic studies (see the following image). [2, 3, 6] The femur, tibia, and humerus are about equally affected and account for approximately 50% of angiosarcoma cases. [4] The vertebrae, pelvic bones, and ribs are less commonly affected sites, but virtually every bone has been reported with these lesions. [2, 2, 5]

Plain film of the tibia demonstrates small lucenci Plain film of the tibia demonstrates small lucencies without internal matrix production in keeping with the diagnosis of a vascular lesion.

The cortex is often eroded with extension into the soft tissues. Although most of these tumors are solitary, multifocal lesions can be seen. Computed tomography (CT) scans can often help in determining intralesional mineralization and the invasive nature of this sarcoma. [2] Magnetic resonance imaging (MRI) findings are relatively nonspecific, with low signal on T1 and high signal on T2 sequences, as seen in the images below. [1, 3]

Coronal T1 magnetic resonance imaging (MRI) study Coronal T1 magnetic resonance imaging (MRI) study reveals a lesion of the diaphysis with cortical breakthrough.
Coronal T2 magnetic resonance image shows a diaphy Coronal T2 magnetic resonance image shows a diaphyseal lesion with intense surrounding edema (high signal intensity).
Axial T2 magnetic resonance image shows a heteroge Axial T2 magnetic resonance image shows a heterogeneous signal lesion with cortical destruction.

Gross, Microscopic, and Immunohistochemical Features

The gross appearance of angiosarcoma is that of soft, dark red tissue that may have a spongy consistency (see the image below). [3] Solid gray areas may be interspersed with embedded bone fragments if the cortex has been breached.

Grossly, angiosarcomas show a reddish-brown color Grossly, angiosarcomas show a reddish-brown color and solid patterns.

On histologic sections, the diagnosis of angiosarcoma is made in areas of well-formed, anastomosing vascular channels [2] lined by enlarged endothelial cells with hyperchromatic or vesicular nuclei (see the first image below). [2] These endothelial cells have a large nuclear-to-cytoplasmic ratio. Although these features are readily identifiable, most skeletal angiosarcomas have poorly differentiated areas without regular vascular channels and can be very difficult to identify. [2, 4, 3] The tumor cells in these areas may be closely packed, round, ovoid, or spindle cells that resemble undifferentiated sarcoma (see the second image below). [6]

Foci of angiosarcomas can show well-formed vascula Foci of angiosarcomas can show well-formed vascular channels that aid in the diagnosis. These channels can be difficult to find in a large number of tumors.
Atypical cells in solid sheets or nests are typica Atypical cells in solid sheets or nests are typical of this tumor and can make diagnosis on hematoxylin and eosin (H&E) sections difficult, necessitating the use of immunohistochemistry.

Immunohistochemistry is often necessary to reach a diagnosis of angiosarcoma, given the anaplasia in most of the tumors. Immunohistochemistry for vimentin, CD31, CD34, and focally for von Willebrand factor are usually positive in these tumors (see the image below). [2, 4, 7]

CD34 immunohistochemistry highlights the vascular CD34 immunohistochemistry highlights the vascular nature of angiosarcomas and aids in the diagnosis.