Hemangioma
Hemangioma is a benign tumor of blood vessels of adulthood that infrequently
involves the bone. Its common osseous sites are the skull, vertebrae, ribs,
and long bones. Symptomatic lesions are rare and the patient usually presents
with an incidental finding on radiography. Skull or rib lesions may manifest
a sunburst pattern on x-ray due to radiating bone spicules in the tumor. Radiographs
of the spine demonstrate prominent thickening of the vertical bony trabeculae
of the vertebral body, or a "honeycombed" pattern. Vertebral body
hemangiomas may weaken the bone and allow a compression fracture to occur. Histologically,
most of these hemangiomas are of the cavernous type. Large, blood-filled channels
lined with endothelial cells are seen. The endothelial cells are inconspicuous
and benign appearing which helps to distinguish these lesions from hemangioendothelioma
and angiosarcoma. The primary treatment is observation for asymptomatic lesions.
Radiation may ablate painful vertebral lesions and laminectomy may be required
if cord compression is present. Care must be taken during surgery as these lesions
may bleed extensively.
Massive osteolysis is a rare condition, also known as Gorham’s disease,
that is characterized by slow and progressive destruction of multiple contiguous
bones. It predilects areas such as the shoulder and pelvis. Most patients are
children and young adults. The bones are replaced by delicate endothelial lined
channels which are indistinguishable from hemangioma.
Glomus Tumor
Glomus tumor is a rare tumor composed of round, uniform cells resembling smooth
muscle cells, associated with vascular spaces. The most common location is the
subungual region of the finger. Secondary erosion of the distal phalanx may
occur. They are always associated with pain. Glomus tumors arising from within
the bone are extremely rare.
Hemangioendothelioma
It is a vascular tumor of intermediate degree of malignancy characterized by
the presence of vascular structures lined by plump endothelial cells. It usually
affects young adults. The tumor involves mostly the bones of the axial skeleton
such as the pelvis and vertebrae, as well as the bones of the lower extremities
including the foot. The lesion can be multifocal in several bones within the
same area, such as the foot. Radiologically, there are osteolytic and are often
well outlined and have sclerotic margins. Histologically, there are anastomosing
vascular spaces and the endothelial lining cells are round to polygonal and
prominent, often with pink cytoplasm. The degree of vascular differentiation
is variable, and mitotic activity is also variable. Inflammatory infiltration
with eosinophils is often present. In epithelioid hemangioendothelioma, the
endothelial cells resemble epithelial cells by their appearance. Distinction
between epithelioid hemangioendothelioma and hemangioma may be difficult, particularly
in hemangiomas that have prominent epithelioid features. Hemangioendothelioma
should be differentiated from metastatic adenocarcinoma and angiosarcoma. The
treatment is curettage for low-grade lesions, and the prognosis is good. Metastasis
occur only in high-grade tumors. There is apparently no difference in prognosis
between solitary and multifocal lesions.
Malignant Vascular Tumors
Angiosarcoma
Angiosarcoma is a rare vascular tumor, even less frequent than hemangioendothelioma.
It has been reported at skeletal sites such as the femur, tibia, and humerus.
The lesions may involve multiple bones or multiple locations in a single bone.
Pain is the usual presenting complaint. Radiographs are nonspecific and demonstrate
destructive lytic lesions with cortical destruction and soft tissue extension.
Histologic examination reveals highly atypical endothelial proliferation. The
neoplastic cells are usually poorly differentiated, and vascular formation is
minimal. The lesions are treated by a wide margin resection or amputation. Radiation
and chemotherapy are also indicated. Angiosarcomas metastasize widely to the
viscera and lymphatics and carry a dismal prognosis for this reason.
Hemangiopericytoma
Hemangiopericytoma is an extremely rare malignant vascular tumor consisting
of abnormal proliferation of capillary channels and pericytes. The lesions occur
in the adult pelvis and present as a tender mass. It has a nonspecific radiographic
appearance, but is most often lytic. Occasionally, a honeycombed appearance
may be seen. Hemangiopericytomas can occur as multiple lesions in a single bone
or in adjacent bones. Microscopically, this hypercellular tumor has many thin-walled
vessels branching throughout, with prominent perivascular proliferation of oval
to elongated pericytic cells. Cellular atypia is present as well mitotic figures,
however the degree of these findings is highly variable. The treatment ranges
from radiotherapy to chemotherapy or surgical ablation depending on the location
and grade of the tumor.
