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Flashcards in Miller- Ortho Onc Bone Deck (40)
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1

Review Bone Tumor Presentation

The patient with a bone tumor may present with pain, a mass, or a fracture, or the mass lesion be incidentally found.

Pain may occur from a mechanical disruption of bone, a pathologic fracture, or compression by an expanding tumor.

Pain may occur with weight bearing and may progress to constant pain at rest that is not relieved by pain medications.

High-grade tumors typically manifest with a short interval of pain (1–3 months).

With low-grade tumors there may be a longer interval of mild to moderate pain (> 3 months).

Osteoid osteoma has a characteristic night pain or diurnal pain pattern relieved with aspirin or NSAIDS.

Bone sarcomas

Malignant neoplasms of connective tissue (mesenchymal) origin

Exhibit rapid growth in a centripetal manner and invade adjacent normal tissues

Each year in the United States, about 2800 new bone sarcomas are diagnosed.

High-grade, malignant bone tumors tend to destroy the overlying cortex and spread into the soft tissues.

Low-grade tumors are generally contained within the cortex or the surrounding periosteal rim.

Bone sarcomas metastasize primarily via the hematogenous route; the lungs are the most common site.

Osteosarcoma and Ewing sarcoma may also metastasize to other bone sites either at initial manifestation or later in disease.

Benign bone tumors

These may be small with a limited growth potential or large and destructive.

Tumor simulators and reactive conditions

These processes occur in bone but are not true neoplasms (e.g., osteomyelitis, aneurysmal bone cyst, bone island).

2

Review Osteoid Osteoma

Self-limiting benign bone lesion

Presentation

Young patient (<30 years of age)

Pain at night, or diurnal pattern that increases with time

Pain is classically relieved by salicylates and other NSAIDs.

Pain may be referred to an adjacent joint, and when the lesion is intracapsular, it may simulate arthritis.

Common locations include the diaphyseal bone, proximal femur, tibia, and spine.

May produce painful nonstructural scoliosis, growth disturbances, and flexion contractures

Scoliosis caused by an osteoid osteoma results in a curve with the lesion on the concave side. This is thought to result from marked paravertebral muscle spasm.

Imaging

Radiographs usually show intensely reactive bone and a radiolucent nidus (Fig. 9.9 in Table 9.20). Because of the intense reactive sclerosis, it may be possible to detect the nidus only with CT or MRI.


 



 

 


 

 

The nidus is less than 1 cm in diameter, although the area of reactive bone sclerosis may be greater.

CT is superior to MRI in detecting and characterizing osteoid osteomas because CT provides better contrast between the lucent nidus and the reactive bone.

Histology

There is a distinct demarcation between the nidus and the reactive bone—nidus shows mineralized woven bone with nonmalignant rimming osteoblasts and appears similar to osteoblastoma.

Trabecular organization is haphazard.

The greatest degree of mineralization is in the center of the lesion.

Treatment

Patients can be treated with three different methods: NSAIDs, CT-guided radiofrequency ablation, and surgical removal.

In about 50% of patients treated with NSAIDs, the lesions burn out over time (several years), with no further medical or surgical treatment necessary.

CT-guided radiofrequency ablation (RFA) is the standard of care.

A radiofrequency probe is placed into the lesion, and the nidus is heated to 80°C.

A lesion close to a critical structure (i.e., neurovascular bundle or the spinal cord) is a contraindication to RFA; in this situation, surgery is preferred.

Differential diagnosis: Osteoblastoma, stress fracture

3

Review osteoblastoma

Bone-producing tumor that is greater than 2 cm; its growth is not self-limiting.

Presentation

Pain

Common locations include the spine, proximal humerus, proximal femur, and acetabulum.

Imaging

Bone destruction with or without the characteristic reactive bone formation in osteoid osteoma.

Area of bone destruction occasionally has a motheaten or permeative appearance simulating a malignancy.

Size is greater than 2 cm (Fig. 9.10A in Table 9.20).

Histology: Mineralized woven bone with nonmalignant rimming osteoblasts that appears similar to osteoblastoma (Fig. 9.10B).

Treatment: Intralesional resection with curettage

Differential diagnosis: Osteoid osteoma and osteoblastoma are easily confused; a comparison is shown in

4

What is the difference between osteoid osteoma and osteoblastoma?

5

Review osteosarcoma

General

Spindle cell neoplasm that produces osteoid

There are many types of osteosarcoma.

Lesions include high-grade intramedullary osteosarcoma (ordinary or classic osteosarcoma), parosteal osteosarcoma, periosteal osteosarcoma, telangiectatic osteosarcoma, osteosarcoma occurring with Paget disease, and osteosarcoma after irradiation.

Presentation: pain or a pathologic fracture

Imaging: Variable according to type

Treatment

Multiagent chemotherapy has dramatically improved long-term survival and the potential for limb salvage.

Agents typically used are:

Doxorubicin (cardiac toxicity)

Cisplatin (neurotoxicity)

Methotrexate (for cases of myelosuppression, leucovorin also administered)

Chemotherapy both kills the micrometastases that are present in 80%–90% of the patients at presentation and sterilizes the reactive zone around the tumor.

Preoperative chemotherapy is delivered for 8–12 weeks, followed by resection of the tumor.

Other features

Rate of long-term survival is approximately 60%–70%.

Osteosarcoma metastasizes most commonly to the lung and next most commonly to bone.

Prognostic factors that adversely affect survival include (1) expression of P-glycoprotein, high serum levels of alkaline phosphatase and LDH, vascular invasion, and no alteration of DNA ploidy after chemotherapy, (2) the absence of anti–heat-shock protein 90 antibodies after chemotherapy, and (3) a poor response to chemotherapy as shown by the presence of histologic tumor necrosis (<90%).

Osteosarcoma is associated with an abnormality in the tumor suppressor genes Rb (retinoblastoma) and p53 (Li-Fraumeni syndrome).

6

Review intramedullary osteosarcoma

Also called “classic” osteosarcoma, this neoplasm is the most common type of osteosarcoma and usually occurs about the knee in children and young adults, but its incidence has a second peak in late adulthood.

Presentation: Pain, in the proximal humerus, proximal femur, and pelvis

Imaging

Radiographs demonstrate a lesion in which there is bone destruction and bone formation (Fig. 9.11 in Table 9.21). On occasion, the lesion is purely sclerotic or lytic.





 



 


 

MRI and CT are useful for defining the anatomy of the lesion with regard to intramedullary extension, involvement of neurovascular structures, and muscle invasion.

Histology: Diagnosis depends on two histologic criteria: (1) the tumor cells produce osteoid and (2) the stromal cells are malignant.

Treatment: Neoadjuvant chemotherapy (i.e., before surgery), followed by wide-margin surgical resection and adjuvant chemotherapy (i.e., after surgery)

Other features: More than 90% of intramedullary osteosarcomas are high-grade and penetrate the cortex early to form soft tissue masses (stage IIB lesions).

7

Review Parosteal osteosarcoma

Parosteal osteosarcoma (low-grade surface)

Presentation

Painless mass that occurs on the surface of the metaphysis of long bones

Most common sites are the posterior aspects of the distal femur, proximal tibia, and proximal humerus.

Imaging: Characteristic radiographic appearance: a heavily ossified, lobulated mass “stuck on bone,” with no intramedullary extension (see Fig. 9.11)

Histology: Regularly arranged osseous trabeculae; between the nearly normal trabeculae are slightly atypical spindle cells.

Treatment

Resection with a wide margin is curative.

Low-grade lesion: Chemotherapy not required

8

Review Periosteal osteosarcoma

Rare surface form of osteosarcoma that occurs most often in the diaphysis of long bones (typically the femur or tibia)

Presentation: Pain

Imaging: Radiographic appearance is fairly constant: a sunburst-type lesion rests on a saucerized cortical depression (Fig. 9.12 in Table 9.21).

Histology: The lesion is predominantly chondroblastic, and the grade of the lesion is intermediate.

Other features

The prognosis for periosteal osteosarcoma is intermediate between those of very low-grade parosteal osteosarcoma (Fig. 9.13 in Table 9.21) and high-grade intramedullary osteosarcoma.

Preoperative chemotherapy, resection, and maintenance chemotherapy constitute the preferred treatment.

The risk of pulmonary metastasis is 10%–15%.

9

Table review comparing osteosarcomas

10

Review MFH

 

"stem cell sarcoma"

Presentation

Pain and swelling.

Most common locations include the distal femur, proximal tibia, proximal femur, ilium, and proximal humerus.

Imaging: This lesion is destructive, with either purely lytic bone destruction or a mixed pattern of bone destruction and formation (Fig. 9.14).

Histology: Malignant fibrous hystiocytoma (MFH) is a primary bone osteosarcoma with a mesenchymal origin and cellular pattern, but no osteoid is produced or seen on histologic examination. The histologic findings determine the diagnosis (i.e., undifferentiated pleomorphic sarcoma [UPS], fibrosarcoma).

Treatment: Same as for osteogenic sarcoma: chemotherapy and surgery.

Other: UPS, MFH, fibrosarcoma, leiomyosarcoma

Presentation and localization are similar to those of osteosarcoma.

Lytic bone destruction is often in a permeative pattern

11

Review table of chondrogenic lesions

12

Review Enchondromas

Enchondroma

Benign cartilage in the medullary cavity in the metaphysis of long bones, especially the proximal femur, humerus, and distal femur.

Presentation: Asymptomatic and found incidentally

Imaging: Radiographically there may be a prominent stippled or mottled calcified appearance (see Fig. 9.17).

Histology: Composed of binuclear cells that lie in lacunar spaces; the lesion is hypocellular, and the cells have a bland appearance (no pleomorphism, anaplasia, or hyperchromasia).

Treatment

When lesions are not causing pain, serial radiographs are obtained to ensure that the lesions are inactive (not growing). Radiographs are obtained every 3–6 months for 1–2 years and then annually as necessary.

For most enchondromas, no treatment other than observation is required. When surgical treatment is necessary, enchondromas are treated with intralesional resection by curettage.

Differential diagnosis

Enchondroma can be distinguished from low-grade chondrosarcoma on serial plain radiographs.

On radiographs of low-grade chondrosarcomas, cortical bone changes (large erosions [>50%] of the cortex, cortical thickening, and destruction) or lysis of the previously mineralized cartilage is visible.

Other features

Enchondromas are also common in the hand, where they usually occur in the diaphysis and metaphysis.

Lesions in the hand may be hypercellular and display worrisome histologic features, and pathologic fractures in the hand are common.

Ollier disease/Maffucci syndrome

When there are many lesions, the involved bones are dysplastic, and the lesions tend toward unilaterality, the diagnosis is multiple enchondromatosis, or Ollier disease.

Inheritance pattern is sporadic.

If soft tissue angiomas are also present, the diagnosis is Maffucci syndrome.

Patients with multiple enchondromatosis are at increased risk of malignancy (in Ollier disease, 30%; in Maffucci syndrome, 100%).

Patients with Maffucci syndrome also have a markedly increased risk of visceral malignancies, such as astrocytomas and gastrointestinal malignancies.

13

Review osteochondromas

Osteochondroma

Benign surface lesions probably arise secondary to aberrant cartilage (from the perichondrial ring) on the surface of bone.

Presentation

Painless mass discovered incidentally.

Occurs about the knee, proximal femur, and proximal humerus.

Imaging

Characteristic appearance: A surface lesion in which the cortex of the lesion and the underlying cortex are confluent with the medullary canal ( see Fig. 9.18).

Osteochondroma may have a narrow stalk (pedunculated) or a broad base (sessile).

The lesion typically occurs at the site of a tendon insertion, and the affected bone is abnormally wide.

Underlying cortex is covered by a thin cap of cartilage (usually only 2–3 mm thick; in a growing child, the cap thickness may exceed 1–2 cm).

Histology: Chondrocytes are arranged in linear clusters, in appearance resembling the normal physis.

Treatment

When asymptomatic, these lesions are treated with observation only.

Surgery is considered when a patient experiences pain secondary to muscle irritation, mechanical trauma (contusions), or an inflamed bursa over the lesion.

Differential diagnosis: Parosteal osteosarcoma, heterotopic ossification

Other features

Malignant transformation (<1% of cases) to a “secondary chondrosarcoma”

Pain in the absence of mechanical factors warns of malignant change.

Destruction of the subchondral bone, mineralization of a soft tissue mass, and an inhomogeneous appearance are radiographic changes of malignant transformation.

A low-grade chondrosarcoma is usually present, although a dedifferentiated chondrosarcoma may occur in rare cases.

The prognosis is excellent; these low-grade tumors rarely metastasize.

Multiple hereditary exostoses

The osteochondromas in MHE are often sessile and large. This is an autosomal dominant condition with mutations in the EXT1 and EXT2 gene loci. In approximately 10% of patients with multiple exostoses, a secondary chondrosarcoma develops. The EXT1 mutation is associated with a greater burden of disease and higher risk of malignancy.

14

Review Chondroblastoma

Centered in the epiphysis in young patients, usually with open physes; it may also occur in an apophysis

Presentation

Pain referable to the involved joint

The most common locations are the distal femur, proximal tibia, and proximal humerus.

Imaging

Shows a central region of bone destruction that is usually sharply demarcated from the normal medullary cavity by a thin rim of sclerotic bone (Fig. 9.19 in Table 9.23).






 


 

 

Mineralization may or may not occur within the lesion.

Histology

The basic proliferating cells are thought to be chondroblasts.

Scattered multinucleated giant cells are found throughout the lesion.

Zones of chondroid are present.

Mitotic figures may be found.

Treatment: Intralesional resection with curettage and reconstruction

Differential diagnosis: Brodie’s abscess and giant cell tumor of bone (Fig. 9.20 in Table 9.23).

Other features: Less than 5% metastasize to the lungs.

15

review chondromxyoid fibroma

Chondromyxoid fibroma

Rare, benign cartilage tumor that contains variable amounts of chondroid, fibromatoid, and myxoid elements

Presentation

Focal pain

Pathognomonic location is the tibia; may also be found in the pelvis and distal femur.

Imaging: A lytic, destructive lesion that is eccentric and sharply demarcated from the adjacent normal bone

Histology: This lesion grows in lobules, and there is often a concentration of cells at the periphery of the lobules.

Treatment: Intralesional curettage

16

Review orthobullets

Chondromyxoid fibroma

A rare and benign chondrogenic lesion characterized by variable amounts of chondroid, fibromatoid and myxoid elements 

Epidemiology demographics 

more common in males

most common in second and third decades of life

may affect patients up to 75 years old

location long bones (ie. tibia, distal femur)

often affects metaphyseal (proximal tibia) regions

pelvis

feet or hands 

Pathophysiology

may arise from physeal remnants 

Genetics mutations 

a genetic rearrangement may affect chromosome 6 (postion q13)

Prognosisnatural historyrecurrence in CMF is not uncommon 

may occur in 20-30% of cases 

negative prognostic variables

children

tumor is more lobulated with abundant myxoid material

metastasis

has not been reported

Presentation

History 

long standing pain (months to years)

may be incidentally identified

Symptoms

pain and mild swelling 

Imaging

Radiographs  findingslytic, eccentric metaphyseal lesion 

sharply demarcated from adjacent bone

scalloped and sclerotic rim 

calcifications are rare

cortical expansion may be seen

lesion size may range from two to ten centimeters

MRI  findings  

low signal on T1-weighted images

high signal on T2-weighted images 

Bone scan findings 

increased signal uptake will be seen 

Studies

Histologyfindingslow-power  biphasic appearancehypercellular area with lobules of fibromyxoid tissue spindle-shaped cells or stellate-shaped cells 

the cells contain hyperchromatic nuclei

multinucleated giant cells and fibrovascular tissue are located between lobules

hypocellular area with chondroid material

high power 

myxoid stroma with stellate cells 

regions of pleiomorphic cells with bizarre nuclei may be seen

Diagnostic criteria 

histopathologic examination is mandatory for confirmation of the diagnosis

Differential

Radiographic 

aneurysmal bone cyst (ABC) 

chondroblastoma 

non-ossifying fibroma  

Histologic 

chondroblastoma 

enchondroma  

chondrosarcoma  

Treatment

Operative intralesional curretage and bone grafting (or PMMA) indications 

mainstay of treatment

Complications

Recurrence 

occurs in 25% of cases

17

Review Cartilage tumors

18

Review MFH

Presentation

Pain and swelling.

Most common locations include the distal femur, proximal tibia, proximal femur, ilium, and proximal humerus.

Imaging: This lesion is destructive, with either purely lytic bone destruction or a mixed pattern of bone destruction and formation (Fig. 9.14).

Histology: Malignant fibrous hystiocytoma (MFH) is a primary bone osteosarcoma with a mesenchymal origin and cellular pattern, but no osteoid is produced or seen on histologic examination. The histologic findings determine the diagnosis (i.e., undifferentiated pleomorphic sarcoma [UPS], fibrosarcoma).

Treatment: Same as for osteogenic sarcoma: chemotherapy and surgery.

Other: UPS, MFH, fibrosarcoma, leiomyosarcoma

Presentation and localization are similar to those of osteosarcoma.

Lytic bone destruction is often in a permeative pattern (Fig. 9.15).

19

review epiphyseal lesions

20

Review nonossifying fibroma

Nonossifying fibroma (also known as metaphyseal fibrous defect, nonosteogenic fibroma, and xanthoma)

Presentation

Asymptomatic, incidentally found lesion in a young patient

Most common locations are the distal femur, distal tibia, and proximal tibia.

Imaging

Characteristic radiographic appearance: A lucent lesion that is metaphyseal, eccentric, and surrounded by a sclerotic rim (Fig. 9.21)

The overlying cortex may be slightly expanded and thinned.

Histology: Cellular, fibroblastic connective tissue background, with the cells arranged in whorled bundles

Treatment

Asymptomatic lesions: Observation if the radiographic appearance is characteristic and there is no risk of pathologic fracture. Lesions resolve spontaneously and are not true neoplasms.

Symptomatic lesions: Curettage and fixation are performed.

21

Review Chordoma

Chordoma is a malignant neoplasm in which the cell of origin is derived from primitive notochordal tissue.

Presentation

Patients present with an insidious onset of pain. Lesions in the sacrum may manifest as pain in the pelvis, low back, or hip or with primarily gastrointestinal symptoms (obstipation, constipation, loss of rectal tone). When vertebral bodies are involved, neurologic symptoms may vary widely because of nerve compression.

Occurs predominantly at the ends of the vertebral column clivus of the skull or sacrum (sacrococcygeal)

About 10% of chordomas occur in the vertebral bodies (cervical, thoracic, and lumbar regions).

Imaging

Radiographs often do not reveal the true extent of sacrococcygeal chordomas.

MRI shows midline bone destruction and a soft tissue mass (Fig. 9.22).

Other MRI findings

Low signal on T1-weighted images

Very bright signal on T2-weighted images

Sacrum is often expanded, and the soft tissue mass may exhibit irregular mineralization.

Histology

The tumor grows in distinct lobules.

Chordoma cells sometimes have a vacuolated appearance and are called physaliferouscells.

Treatment

Wide-margin surgical resection

Radiation therapy may be added if a wide margin is not achieved.

Other features: Chordomas metastasize late in the course of disease, and local extension can be fatal.

22

Blue Cell tumors

 

LERNM

23

Review lymphomas

Presentation

Pain in patients of all ages.

The most common locations include the distal femur, proximal tibia, pelvis, proximal femur, vertebra, and shoulder girdle.

Imaging

Images often show a lesion that involves a large portion of the bone (Fig. 9.23).

Bone destruction is common and often has a mottled appearance.

A large soft tissue mass out of proportion to the amount of bone destruction is characteristic of lymphoma of bone.

Histology

A mixed cellular infiltrate is usually present. Most lymphomas of bone are diffuse, large B-cell lymphomas.

IHC: CD45 and leukocyte common antigen (LCA) positive.

Treatment

Multiagent chemotherapy ( [CHOP]) is curative.

Surgery is used only to stabilize fractures.

24

Review Myeloma

Plasma cell dyscrasias represent a wide range of conditions from monoclonal gammopathy of undetermined significance (MGUS; Kyle disease) to multiple myeloma.

Three plasma cell dyscrasias pertain to orthopaedic surgery: multiple myeloma, solitary plasmacytoma of bone, and osteosclerotic myeloma.

Multiple myeloma

Malignant plasma cell disorder that commonly occurs in patients between 50 and 80 years of age

Presentation: Manifests with bone pain, usually in the spine and ribs, or as a pathologic fracture

Fatigue is a common complaint secondary to the associated anemia.

Symptoms may be related to complications such as renal insufficiency, hypercalcemia, and the deposition of amyloid.

Serum creatinine values are elevated in about 50% of affected patients.

Hypercalcemia is present in about 33% of affected patients.

Imaging: Radiographic appearance is of punched-out, lytic lesions (see Fig. 9.13), which may show expansion and a “ballooned” appearance.

Histology

Sheets of plasma cells that appear monoclonal with immunostaining

Well-differentiated plasma cells have eccentric nuclei that have peripherally clumped, chromatic “clock faces.”

Treatment

Systemic therapy and bisphosphonates

Surgical stabilization with irradiation is used for pathologic fractures.

Radiotherapy is also used for palliation of pain and treatment of neurologic symptoms.

The prognosis is related to the stage of disease; the overall median survival time is 18–24 months.

25

Review solitary plasmacytoma

It is important to differentiate solitary myeloma from multiple myeloma because of the more favorable prognosis in patients with the solitary form. Diagnostic criteria include the following:

A solitary lesion on skeletal survey

Histologic confirmation of plasmacytoma

Bone marrow plasmacyte count of 10% or less

Patients with serum protein abnormalities and Bence Jones proteinuria (protein levels <1 g/24 hr) at presentation are not excluded if they meet the aforementioned criteria.

Treatment

External beam irradiation of the lesion (4500–5000 cGy)

When necessary, prophylactic internal fixation

In approximately 50%–75% of affected patients, solitary myeloma progresses to multiple myeloma.

26

Review Giant Cell tumor

Giant cell tumor of bone

Presentation

Pain and pathologic fracture

Patients over 30 years old with closed physes

Most common in the epiphysis and metaphysis of long bones, and about 50% of lesions occur about the knee; the vertebra, sacrum, and distal radius are involved in about 10% of cases.

The sacrum is the most common axial location of giant cell tumors of bone.

Imaging: A purely lytic destructive lesion in the metaphysis that extends into the epiphysis and often borders the subchondral bone (see Fig. 9.20).

Histology

Basic proliferating cell has a round to oval or even spindle-shaped nucleus, and the multinucleated giant cells appear to have the same nuclei as the proliferating mononuclear cells. The stromal cell directs the multinucleated giant cell.

Stromal malignant cells produce RANKL (receptor activator for nuclear factorκB ligand).

Multinucleated giant cells express RANK and are responsible for the osteolytic aspect of GCT.

Treatment

Aimed at removing the lesion, with preservation of the involved joint

Denosumab (Prolia), a human monoclonal antibody that binds RANKL, thereby inhibiting the maturation of osteoclasts.

Extensive intralesional resection (removal of a large cortical window over the lesion) is performed using curettage with manual and power instruments.

Chemical cauterization may be used (phenol, peroxide).

Area of defect is usually reconstructed with subchondral bone grafts, methylmethacrylate, or both.

Local control with this treatment regimen has a success rate of 85%–90%.

Other features: GCT is described as benign but is aggressive, because in rare cases (<5%) it metastasizes to the lungs.

27

Review Ewing Sarcoma

Presentation

Patient age less than 30 years

Pain and fever may be present; the presentation can be similar to that in an infection.

Patients may exhibit elevated ESR, leukocytosis, anemia, and elevated WBC count.

Most common locations include the pelvis, distal femur, proximal tibia, femoral diaphysis, and proximal humerus.

Imaging

Radiographs often show a large, destructive lesion that involves the metaphysis and diaphysis.

The lesion may be purely lytic or may have variable amounts of reactive new bone formation (Fig. 9.24).

The periosteum may be lifted off in multiple layers, producing a Codman triangle and an onion-skin appearance.

The soft tissue component is distinctively large.

Histology

Small round blue cells with minimal cytoplasm, pseudorosettes (attempted formation of vascular channels)

ICH: CD99 positivity.

A classic 11:22 chromosomal translocation produces the EWS-FLI1 fusion gene.

Bone marrow biopsy is performed for staging purposes.

Treatment: A multimodality approach with multiagent chemotherapy, irradiation, and surgical resection

Standard treatment includes chemotherapy.

Standard for local tumor control is surgery.

Radiation therapy may be used primarily for pelvic and spine disease, where resection would be morbid, or as an adjunct to surgery to maintain function while sparing critical structures.

Differential diagnosis: When a small blue cell tumor is found in a child younger than 5 years, metastatic neuroblastoma and leukemia should be considered.

Other features

Survival

The rate of long-term survival with multimodality treatment may be as high as 60%–70%.

There is a consistent chromosomal translocation (11;22) with the formation of a fusion protein (EWS-FLI1).

Metastatic disease involves the lungs (50%), bone (25%), and bone marrow (20%).

Poor prognostic factors include the following:

Spine and pelvic tumors

Tumors greater than 100 cm3 in diameter

A poor response to chemotherapy (<90% tumor cell necrosis)

Elevated serum LDH (Temple)

The p53 mutation and gene fusion products other than EWS-FLI1

28

Review Adamantinoma

Rare low-grade, malignant tumor of long bones that contains epithelium-like islands of cells

Presentation

Patient less than 30 years old with prolonged periods of pain

The tibia is the most common site; other long bones can be but rarely are involved (fibula, femur, ulna, radius).

Imaging: Radiographic appearance: multiple, sharply circumscribed, “soap bubble”–looking lucent defects of different sizes, with sclerotic bone interspersed between the zones and extending above and below the lucent zones (see Fig. 9.28 in Table 9.26); one of the lesions in the midshaft is the largest and is associated with cortical bone destruction.

Histology: Cells have an epithelial quality and are arranged in a palisading or glandular pattern; the epithelial cells occur in a fibrous stroma.

Treatment: Wide-margin surgical resection

Other features: Tumor may metastasize either early or after multiple failed attempts at local control.

29

Review ABC vs UBC

30

Review ABC

Aneurysmal bone cyst

Nonneoplastic reactive condition that may be aggressive in its ability to destroy normal bone and expand into the soft tissues

Presentation: Patients are less than 30 years old and present with pain and swelling.

Imaging

Characteristic radiographic finding: an eccentric, lytic, expansile area of bone in the metaphysis with a thin rim of periosteal new bone surrounding the lesion. The lesion is wider than the physis of the bone it is closest to (Fig. 9.25 in Table 9.25).

MRI usually shows the periosteal layer surrounding the lesion.

Fluid-fluid levels visible on T2-weighted MRI are characteristic of, but not exclusive to, ABC.

Histology

Cavernous blood-filled spaces without an endothelial lining.

Thin strands of bone are present in the fibrous tissue of the septa.

Benign giant cells may be numerous.

Treatment: Curettage and reconstruction, which may include bone grafting or fixation in the setting of a fracture.

Differential diagnosis: Unicameral bone cyst, telangiectatic osteosarcoma

Other features

Local recurrence is common in children with open physes.

ABC may arise primarily in bone or may be found in association with other tumors, such as giant cell tumor, chondroblastoma, chondromyxoid fibroma, and fibrous dysplasia.