Musculoskeletal Angiomatous Lesions

Radiologic-Pathologic Correlation

Abstract Introduction Hemangioma Lymphangioma

Glomus Tumor Angiomatosis Angiomatous Syndromes and Associated Conditions Hamangioendothelioma, Hemangiopericytoma, and Angiosarcoma

Biopsy, Treatment, and Prognosis Summary Source Information References

Hamangioendothelioma, Hemangiopericytoma, and Angiosarcoma

Hemangioendothelioma is a neoplasm of vascular endothelial cells of intermediate aggressiveness that can be either benign or malignant. Both hemangiomas and hemangioendotheliomas can be of the epithelioid (histiocytoid) subtype when the endothelial cells have an epithelial appearance (76,77). Hemangioendothelioma occurs in young patients and involves soft tissue more commonly than bone. Soft-tissue hemangioendothelioma usually involves the deep tissues of the extremities, with 50% of the cases being closely related to a vessel (often a vein) from which they may have arisen (78). Osseous hemangioendothelioma most frequently affects the calvaria, spine, or lower extremities and is slightly more common in men in the 2nd 3rd decades of life (75).

Hemangiopericytoma arises from the cells of Zimmerman that are located around vessels. It also is a tumor of intermediate aggressiveness that has both benign and malignant forms. The tumor is often characterized by large vessels predominantly located in its periphery. Hemangiopericytoma commonly involves the lower extremity (35% of cases), particularly the soft tissues of the thigh, and the pelvis and retroperitoneum (25%), most frequently in middle-aged adults (49). Primary osseous lesions are rare.

Angiosarcoma is an aggressive, vascular malignancy with frequent local recurrence and distant metastasis. Pathologically, these tumors may contain either hemangiomatous or lymphangiomatous cellular elements, which are often difficult or impossible to distinguish histologically, particularly with higher degrees of anaplasia. Identification of vascular channels allows diagnosis; thus, the term angiosarcoma is preferable to hemangiosarcoma or lymphangiosarcoma for these malignant vascular neoplasms. Angiosarcomas involve the skin (33% of cases), soft tissues (24%), and bone (6%), with other sites accounting for the remainder of cases (79). Men are affected twice as frequently as women. This is the type of sarcoma associated with chronic lymphedema (only 10% of cases of angiosarcoma) that develops in postmastectomy patients (Stewart-Treves syndrome) (78). The most common osseous location of angiosarcoma is the long bones (approximately 60% of cases), specifically the tibia (23%), femur (18%), humerus (13%), and pelvis (7%) (5).

It is not possible to differentiate between hemangioendothelioma, hemangiopericytoma, and angiosarcoma radiologically. Radiographs of soft-tissue lesions usually reveal only a nonspecific mass. Osseous lesions (Figure 18, Figure 19) are predominantly lytic and may reveal a honeycomb or hole-within-hole appearance similar to that of hemangioma. However, more aggressive features of marked osseous expansion, cortical permeation, and an associated soft-tissue mass are frequently present in higher-grade lesions (Figure 18, Figure 19). There is often multifocal osseous involvement separated by normal bone that may affect bone on both sides of a joint (Figure 18). Sclerosis, particularly at the osseous margins, can be seen in lower-grade lesions.

Angiograms reveal dense, well-circumscribed areas of staining with early draining veins and shunting. Hemangiopericytoma may have a more characteristic appearance, with a pedicle formed by the arteries supplying the tumor (80). From this vascular pedicle, vessels arborize to encircle the tumor, which displaces major vessels.

Sonographic and CT descriptions of soft-tissue hemangioendothelioma, hemangiopericytoma, and angiosarcoma are limited (81,82,83). At US, lesions may be hypoechoic or hyperechoic and are often complex, with cystic areas resulting from hemorrhage. Doppler US studies often reveal arteriovenous shunting. CT findings are usually nonspecific, consisting of a soft-tissue mass with attenuation similar to that of muscle, although the mass usually markedly enhances with contrast material (Figure 20).

MR imaging characteristics of hemangioendothelioma, hemangiopericytoma, and angiosarcoma, like those of CT and sonography, may also be nonspecific. In our experience, however, prominent serpentine vessels can be identified in some cases, and these findings should suggest these diagnoses. These vascular channels occur most often in the periphery of the mass and are particularly prominent in hemangiopericytoma, reflecting the vascular supply (Figure 20). The signal intensity of these vascular structures may reflect either high flow (low signal intensity on images of all pulse sequences) or low flow (high signal intensity on T2-weighted images). With the exception of alveolar soft part sarcoma, rhabdomyosarcoma, and extraskeletal Ewing sarcoma, other soft-tissue sarcomas, even when hypervascular, rarely show definable prominent vessels at MR imaging in our experience. Overall, these more aggressive vascular lesions have intermediate signal intensity on T1-weighted images and very high signal intensity on MR images obtained with long repetition times (Figure 20). Compared with hemangiomas, however, these lesions have no fat overgrowth and have more aggressive features of infiltration of the surrounding tissues. Areas of hemorrhage with high signal intensity on T1-weighted MR images and fluid-fluid levels may also be seen.

Abstract Introduction Hemangioma Lymphangioma

Glomus Tumor Angiomatosis Angiomatous Syndromes and Associated Conditions Hamangioendothelioma, Hemangiopericytoma, and Angiosarcoma

Biopsy, Treatment, and Prognosis Summary Source Information References