Benign Tumors

On the benign end of the tumor spectrum, there are several lesions whose appearance is usually diagnostic, including enostosis, osteoid osteoma, hemangioma, and osteochondroma. Enostoses, or bone islands, are benign incidental lesions detected on imaging, which occasionally are mistaken for sclerotic metastases. They are classically round to oval in shape, sharply defined, and have characteristic spiculated margins. Most lesions do not demonstrate activity on bone scintigraphy although giant bone islands (>2 cm) may show increased uptake. On rare occasions, interval growth will prompt biopsy to prove its benign etiology.

Osteoid osteoma is a lesion of young patients, usually between the ages of 10 and 20 yr, with a male predominance (3:1). It should be noted that only 10% of osteoid osteomas involve the axial skeleton. The classic clinical history in such cases is painful scoliosis, but it may also present with localized pain, radiculopathy, or gait disturbance. The pain tends to be worse at night and is typically relieved with aspirin or nonsteroidal antiinflammatory drugs (NSAIDs). Spinal lesions tend to involve the posterior elements (75%) and involvement of the lumbar spine is most frequent (59%), followed by the cervical (27%), thoracic (12%), and sacral (2%) regions. On CT, the lesion is round to oval with a central radiolucent nidus that is surrounded by a variable extent of reactive sclerosis. The central nidus is usually <1.5 cm in diameter and may contain a focus of calcification. Although the lesion may heal spontaneously, complete surgical resection of the nidus is often needed for cure. CT-guided percutaneous excision or ablation of the nidus has also been described (19).

A vertebral hemangioma is a very common incidental finding on spine imaging studies (Fig. 8). On MRI, the lesions are usually of high signal intensity on both T1- and T2-weighted images with a subtly variegated internal architecture. Hemangiomas are most frequently found in the vertebral body although extension into the pedicles and laminae is well described. Isolated involvement of the posterior elements is uncommon. Rarely there is a soft tissue component with extension into the paraspinal soft tissues or spinal canal. The CT appearance is virtually pathognomonic and is characterized by a geographic zone of radiolucency that contains an internal scaffold of coarse vertical trabeculae, the so-called "corduroy" pattern. CT is very useful for confirming the diagnosis of hemangioma when the MRI appearance is atypical.

Spinal osteochondromas are uncommon tumors that can be seen sporadically as solitary lesions or in the setting of hereditary multiple exostoses. Patients are young, usually in the third or fourth decade, and there is a male predominance. Any part of the spine may be affected but the cervical region is most often involved. Myelopathy is a frequent presenting manifestation although trauma may uncover an otherwise asymptomatic lesion. Osteochon-dromas that project anteriorly may cause dysphagia, vocal cord dysfunction, or vascular compromise. The lesion may be sessile or pedunculated. As with exostoses in the appendicular skeleton, the characteristic finding is lesion continuity with the underlying vertebral cortex and marrow, which is well depicted by CT. Both CT and MRI are well suited to demonstrate the degree of accompanying spinal canal stenosis or mass effect on paravertebral structures. Osteochondromas rarely undergo malignant transformation into a secondary chondrosarcoma (19).

There are three primary spinal tumors that are considered pathologically benign but that may have aggressive clinical features on the basis of size and an expansile growth pattern. These are the aneurysmal bone cyst, osteoblastoma, and giant cell tumor. All three lesions tend to occur in younger patients. Although histologically benign, these tumors have substantial recurrence rates if not completely resected. Complete resection of large lesions is often impossible in the spine as a result of the associated morbidity.

Aneurysmal bone cyst (ABC) in the spine most often involves the thoracic region. Involvement of the sacrum, unlike giant cell tumor, is rare. Pathologically, the lesion is characterized by multiple blood-filled cystic spaces. On CT and MRI, a multicystic mass with expansile remodeling is found with characteristic fluid-fluid levels, indi

Giant Cell Tumor Vertebral Body

Fig. 8. (A) Sagittal CT reformation reveals predominately osteolytic foci involving both the L1 and L2 vertebrae in a patient with suspected metastatic breast carcinoma. (B) Axial CT at the L1 level shows irregular areas of lytic bone destruction with a small break in the cortex laterally. This proved to be metastatic disease. (C) Axial CT at the L2 level demonstrates the classic "corduroy" appearance of a vertebral hemangioma. Note the prominent vertically oriented trabeculae on both the axial and sagittal images.

Fig. 8. (A) Sagittal CT reformation reveals predominately osteolytic foci involving both the L1 and L2 vertebrae in a patient with suspected metastatic breast carcinoma. (B) Axial CT at the L1 level shows irregular areas of lytic bone destruction with a small break in the cortex laterally. This proved to be metastatic disease. (C) Axial CT at the L2 level demonstrates the classic "corduroy" appearance of a vertebral hemangioma. Note the prominent vertically oriented trabeculae on both the axial and sagittal images.

cating the presence of hemorrhage. A thin outer rim of preserved periosteum is typical although it may be interrupted. The lesion is usually centered on the posterior elements although involvement of the vertebral body is common (75-90%). Direct extension to involve adjacent ribs and vertebral bodies has been described (Fig. 9). ABCs are vascular lesions and embolization can be performed as a primary treatment or preoperatively to minimize blood loss at surgery. ABCs are also radiosensitive (19).

Like ABC, osteoblastoma ofthe spine most often localizes to the posterior elements with extension into the vertebral body being fairly common (42%). Smaller lesions have an appearance very similar to osteoid osteoma with a central lucent region surrounded by reactive sclerosis. With this type of osteoblastoma, the only distinction from osteoid osteoma is based on size (>1.5 cm). At the other end of the spectrum is an aggressive, expansile mass with bone destruction, paraspinal soft tissue infiltration, and multifocal mineralization that may resemble chondroid

Paraspinal Soft Tissue Structures

Fig. 9. Axial CT (A) and sagittal CT reformation (B) demonstrate expansile, destructive lytic lesions involving both the T2 and T3 vertebral levels. There is involvement of the anterior and posterior elements with vertebral collapse and accompanying kyphosis. Differential considerations would include primary and secondary spinal malignancies (metastatic disease, multiple myeloma, or lymphoma) as well as benign aggressive lesions such as aneurysmal bone cyst (ABC) or osteoblastoma. (C, D) Sagittal and axial STIR demonstrate a characteristic multiloculated, cystic appearance with fluid-fluid levels (indicating hemorrhage). Although not entirely specific, this pattern strongly suggests the diagnosis of ABC, which was confirmed surgically.

Fig. 9. Axial CT (A) and sagittal CT reformation (B) demonstrate expansile, destructive lytic lesions involving both the T2 and T3 vertebral levels. There is involvement of the anterior and posterior elements with vertebral collapse and accompanying kyphosis. Differential considerations would include primary and secondary spinal malignancies (metastatic disease, multiple myeloma, or lymphoma) as well as benign aggressive lesions such as aneurysmal bone cyst (ABC) or osteoblastoma. (C, D) Sagittal and axial STIR demonstrate a characteristic multiloculated, cystic appearance with fluid-fluid levels (indicating hemorrhage). Although not entirely specific, this pattern strongly suggests the diagnosis of ABC, which was confirmed surgically.

matrix (rings and arcs). Treatment is surgical resection. The recurrence rate for the aggressive form is approx 50% vs 10-15% for the more indolent subtype. Malignant transformation is rare but has been reported.

Giant cell tumors (GCTs) differ from the other two lesions in that the most arise in the sacrum. In addition, involvement of the spine usually localizes to the vertebral body rather than the posterior elements. Necrosis and hemorrhage within a GCT may create an appearance similar to an ABC. Unlike GCTs of the long bones, lesions of the sacrum and spine have a tendency to spread across natural boundaries, such as the intervertebral disc space and sacroiliac joint. This finding may lead to a misdiagnosis of infection. Treatment for GCTs is surgical resec

Severe Spinal StenosisPaget Disease Vertebra

Fig. 10. Lateral radiograph (A) displays a relatively lucent appearance of the L2 vertebral body with loss of height and some widening in the anteroposterior dimension. Axial CT (B) shows the characteristic features of Paget's disease with a coarse trabecular pattern and osseous expansion, which results in severe spinal canal stenosis.

tion. Incompletely resected tumors are treated with radiation. The prognosis of GCT of the spine is less favorable than for the other benign tumors. Recurrence is expected in 40-60% of cases. Malignant transformation of GCTs is described in 10-15% of cases although there is speculation that the majority of these may actually represent radiation-induced sarcomas (19).

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Responses

  • Helena Groop
    What is prominent hemangioma in the l1 vertebral body?
    8 years ago
  • Amanda
    Are benign tumors usually oval in shape?
    7 years ago
  • YOLANDA
    What is a primary t11t12 thoracic hemangioma within the vertebral body?
    6 years ago
  • david
    Is vertebral ostenocorcis benign?
    6 years ago
  • cian
    What is an expansile lesion of T3 vertebral body?
    6 years ago
  • Allison Provencher
    Are all small lesions on L2 vertebral malignant?
    6 years ago
  • Laurence
    What is a focal radiolucent lesion in a vertebral body?
    2 years ago
  • grimalda
    Can a focal benign lesion as hemangioma in vertebral body of T6 turn into cancer?
    1 year ago

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