Hamartoma Workup

Updated: Oct 23, 2017
  • Author: Rohit Seth, MD, PhD, MRCS(Edin); Chief Editor: Harris Gellman, MD  more...
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Workup

Laboratory Studies

Laboratory studies are not required unless patients are symptomatic. If needed, laboratory tests may include the following preoperative investigations:

  • Complete blood count (CBC)
  • Measurement of urea, electrolyte, calcium, phosphate, and alkaline phosphatase levels
  • Liver function tests if metastases are suspected

Further investigations are unnecessary.

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Plain Radiography

Bone-forming tumors

With bone islands, the results of basic investigations are inconclusive. As noted, these lesions are commonly incidental findings. On radiography, bone islands appear as round or ovoid areas with flecks of increased opacity in cancellous bone (see the image below).

Bone island. On plain radiographs, bone islands ty Bone island. On plain radiographs, bone islands typically appear as round-to-ovoid, sclerotic intramedullary foci. The long axis of the bone island is aligned parallel to the long axis of the bone.

With osteopoikilosis, lesions are symmetrical and unequally distributed. They have a predilection to involve the epiphysis and metaphysis of long tubular bones. Radiographs show numerous discrete and homogeneous areas of increased radiopacity that are 3-5 mm in diameter. Findings are similar to those observed with bone islands (see the image below).

Osteopoikilosis. Plain radiograph of the pelvis sh Osteopoikilosis. Plain radiograph of the pelvis shows numerous bone islands characteristic of osteopoikilosis.

With melorheostosis, radiographs show well-defined lesions with undulating contours and a linear pattern of distribution (see the image below).

Melorheostosis. Image vividly depicts the characte Melorheostosis. Image vividly depicts the characteristic flowing-wax or flowing-hyperostosis appearance.

With osteopathia striata, lesions are often seen as bilateral linear bands of increased radiopacity on radiography, with interspersed areas of rarefaction (see the image below).

Osteopathia striata. This condition is characteriz Osteopathia striata. This condition is characterized by longitudinal striations, which often appear at the metaphysis.

Cartilage-forming tumors

With osteochondroma and multiple osteochondromas, radiographs depict pedunculated or sessile masses with well-defined margins. When the tumors are pedunculated, the stalk points away from the adjacent joint surface. The cortex and the medullary cavity of the osteochondroma and the adjacent bone are continuous (see the image below).

Solitary osteochondroma. Anteroposterior radiograp Solitary osteochondroma. Anteroposterior radiograph shows sessile osteochondroma of the humerus. See Image 6.

With epiphyseal osteochondroma and enchondromatosis, radiographs demonstrate radiolucent, often expansile lesions with a varied cartilaginous matrix and smooth or lobulated margins (see the images below).

Epiphyseal osteochondroma. Image shows the anterop Epiphyseal osteochondroma. Image shows the anteroposterior knee of a 6-year-old boy. Characteristic lobular ossific masses are protruding from the medial distal femoral epiphysis (arrowhead).
Solitary enchondroma. Frontal radiograph of the ri Solitary enchondroma. Frontal radiograph of the right hand demonstrates a lytic expansile lesion in the fifth metacarpal bone, with thinning of the cortex that has a somewhat scalloped appearance. A pathologic fracture is noted, but no calcifications are seen in the lesion. See Image 9.
Solitary enchondroma. Detail of the lytic expansil Solitary enchondroma. Detail of the lytic expansile lesion in the fifth metacarpal bone in the right hand depicted in Image 8. This image shows thinning of the cortex, with a somewhat scalloped appearance. A pathologic fracture is noted, but no calcifications are seen in the lesion.

Fiber-forming tumors

With nonossifying fibroma, radiographs show oval radiolucent lesions with ridged trabeculations in the bony wall and sclerotic borders. These lesions can also become involuted, resulting in the classic ground-glass or sclerotic appearance; this finding obviates further imaging.

With fibrous dysplasia, radiographic findings are the same in monostotic or polyostotic disease. Solitary lesions are usually small. Radiographs often depict centrally located, round, and expansile lesions. The lesions are either radiolucent or have a ground-glass appearance, which is usually due to new bone formation. The margins can be sharply defined or sclerotic (see the images below).

Fibrous cortical defect and nonossifying fibroma. Fibrous cortical defect and nonossifying fibroma. Anteroposterior radiograph of the distal tibia shows a lobulated, well-circumscribed nonossifying fibroma that is eccentrically located in the distal tibia metadiaphysis. The peripheral sclerotic border with a central lucency is typical of this lesion.
Fibrous dysplasia. Image shows homogeneous loss of Fibrous dysplasia. Image shows homogeneous loss of the normal trabecular pattern in the shaft of the humerus, with a ground-glass appearance.

Benign non-matrix-forming tumors

With hemangioma of bone or skeletal hemangiomatosis or lymphangiomatosis, radiographs show vertical striations reflecting the thickened trabeculae of the vertebral bodies. These cause the characteristic corduroy or honeycomb pattern appearance (see the image below).

Bone hemangioma. Radiograph depicts the typical co Bone hemangioma. Radiograph depicts the typical corduroy or accordion appearance of coarse, thickened vertical trabeculae in a hemangioma affecting the right side of the vertebral body at L2.
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CT, MRI, Ultrasonography, Bone Scanning, and Angiography

Bone-forming tumors

With bone islands, computed tomography (CT) shows no alteration in the contour of the bone. On magnetic resonance imaging (MRI), the compactness of the bone results in low signal intensity in cancellous bone on T1- and T2-weighted images. Bone scans usually show no activity; however, increased uptake has been documented in the literature.

With osteopoikilosis, bone scans usually depict no increase in uptake, though cases of uptake are reported in the literature.

With melorheostosis, CT scans highlight thickening of the cortex. On MRI, the lesions have the same features as those of cortical bone. Bone scintigraphy shows increased bone activity. [43]

Cartilage-forming tumors

With osteochondroma and multiple osteochondromas, CT is useful for delineating osteochondromas in complex bones, such as those of the pelvis, shoulder, or spine (see the image below). MRI and ultrasonography are useful for evaluating the thickness of the cartilage cap. Bone scans are useful for differentiating benign from malignant osteochondromas; a normal scan practically eliminates the likelihood of malignancy. Angiography is relevant if the patient has vascular complications.

Solitary osteochondroma. CT scan of the sessile os Solitary osteochondroma. CT scan of the sessile osteochondroma of the humerus shown in Image 5.

With epiphyseal osteochondroma and enchondromatosis, CT scans often highlight the extent of the lesion. [44]

Fiber-forming tumors

With nonossifying fibroma, CT and MRI are used only to delineate cortical involvement in doubtful cases. Radionuclide imaging shows low-grade activity secondary to the new bone formation surrounding the lesion.

Initially, nonossifying fibromas have a high or intermediate T2 signal with a low signal rim corresponding to a sclerotic border. As the lesions matures and ossifies, the signal changes to become low signal. [45, 46]

With fibrous dysplasia, CT and MRI are often unnecessary, but the images can highlight cystic degeneration, aneurysmal formation, and cortical bony destruction. Bone scintigraphy and arteriography also yield positive results in most cases.

Benign non-matrix-forming tumors

With hemangioma of bone and skeletal hemangiomatosis and lymphangiomatosis, CT scans show a coarsened appearance. On MRI, both T1- and T2-weighted images show increased signal intensity. MRI is the criterion standard for investigating vertebral hemangioma. Active lesions generate a low T1 and a high T2 signal, and quiescent lesions generate both high T1 and T2 signals. It is imperative that vertebral hemangioma be distinguished from giant cell tumors of the spine, metastatic lesions, and aneurysmal bone cysts. [47, 48, 49]

Angiograms depict a prominent tumoral blush. Radionuclide bone scans do not always yield positive results; however, they may be of value in locating multiple lesions. Lymphography often demonstrates abnormal and dilated vessels filling the bony lesions.

They are the most common benign tumor of the spinal column, usually within the vertebral body. [38]  The lesions occur most commonly in the lower thoracic vertebrae, less frequently in the lumbar spine, and infrequently in the cervical spine and sacrum. [50, 51]

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Histologic Findings

Characteristic histologic findings of hamartomas are as follows:

  • Bone island - One sees dense normal bone that is distinctly separated from the surrounding cancellous spicules
  • Osteopoikilosis - Nodules of bone appear with connected spicules of cancellous bone
  • Melorheostosis - Irregular bone with decreased cellular activity is observed on the endosteal surfaces; also seen is an irregular mixture of lamellar and woven bone
  • Osteopathia striata - Abnormally thick bone trabeculae are seen; tightly packed haversian canals may be found in a compacted cortical department; bone lamellation and remodeling are usually unaffected
  • Osteochondroma and multiple osteochondromas – There is a thick proliferating cartilage cap that overlies poorly organized cancellous bone, with endochondral ossification evident at the base of the cap; in a skeletally mature individual, a thick and actively proliferating cap on an exostosis may indicate malignant change
  • Epiphyseal osteochondroma - This lesion has a cartilaginous appearance, with ossification at the periphery; it is partly covered with a fibrous membrane
  • Enchondromatosis - Atypical chondrocytic clones actively proliferate in the cartilaginous epiphysis; the degree of cellularity is greater than that seen with solitary enchondromas, and the cartilaginous nodules have a lobular and cellular appearance
  • Nonossifying fibroma - A mixed degree of cellularity is apparent, with areas of high cellularity combined with areas of collagenous stroma; the stroma of spindle cells displays a cartwheel (storiform) pattern; occasional giant cells and mitoses are other features
  • Fibrous dysplasia - Microscopic appearance shows a fibrous-collagenous matrix with randomly oriented bone or fiber trabeculae formed by osseous metaplasia of spindled stromal cells; the spicules of immature bone produced are short and irregular and are not lined by osteoblasts; the appearance has been described as resembling Chinese letters; small nodules of cartilage are found within the fibrous matrix in 10% of cases
  • Hemangioma of bone - Bone hemangiomas characteristically show increased vascular channels of various sizes and shapes; another finding is reactive formation of bone (usually immature and irregular) at the periphery of the lesion
  • Skeletal hemangiomatosis/lymphangiomatosis - Lymphangiomas consist of thin-walled, vascular spaces lined with flattened endothelial cells and separated by collagenous septa
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