2

A. Workup for Bone Lesion (Fig. 2.1)

1. Biopsy should be performed by treating surgeon at a sarcoma center.

2. Common reason for referral to orthopaedic oncologist is incomplete excision of an unknown sarcoma. Always refer suspicious lesions to surgeon at a sarcoma center.

3. Regardless of a known primary, a new lesion without a previous diagnosis of metastatic bone disease should be biopsied.

B. Workup for Soft Tissue Sarcoma

See Soft Tissue Tumors section, below.

C. Staging

1. Enneking staging for malignant bone tumors (Table 2.1)

2. Enneking staging for benign bone tumors

• Stage 1: latent [nonossifying fibroma (NOF), enchondroma]

• Stage 2: active [aneurysmal bone cyst (ABC)/unicameral bone cyst (UBC), chondroblastoma]

• Stage 3: aggressive (giant cell tumor of bone)

3. American Joint Committee on Cancer (AJCC) staging for malignant bone tumors (Table 2.2)

• Stage is most important prognostic factor for survival.

• Presence or absence of metastatic disease has most significant impact on long-term survival of a primary bone sarcoma.

4. AJCC staging for soft tissue sarcomas (Table 2.3)

D. Treatment

1. Goal is to remove lesion with minimal risk of recurrence.

Fig. 2.1 Workup of bone lesion. Abd, abdomen; Alk P, alkaline phosphatase; Ca, calcium; CBC, complete blood count; CRP, C-reactive protein; CT, computed tomography; ESR, erythrocyte sedimentation rate; LDH, lactate dehydrogenase; LFT, liver function test; MRI, magnetic resonance imaging; P, phosphorus; PSA, prostate-specific antigen; PT, prothrombin time; PTT, partial thromboplastin time; SPEP, serum protein electrophoresis; UA, uranalysis; UPEP, urine protein electrophoresis.

Table 2.1 Enneking System for Staging Malignant Bone Tumors

2. Surgical margins (Fig. 2.2)

• Intralesional: within tumor

• Marginal: through reactive zone around tumor

• Wide: cuff of normal tissue surrounding

• Radical: removal of entire compartment

3. Adjuvant therapy

• Chemotherapy: multiagent chemotherapy for osteogenic sarcoma and Ewing’s sarcoma with improved survival and limb salvage

a. Mechanism of chemotherapy: induction of apoptosis

b. For both osteogenic sarcoma and Ewing’s sarcoma, preoperative chemotherapy followed by restaging, surgery, and then additional chemotherapy

c. Chemotherapy controversial for soft tissue sarcomas

d. Common chemotherapy agents (Table 2.4)

• Radiation: used for Ewing’s sarcoma, lymphoma, myeloma, metastatic bone disease, soft tissue sarcoma

a. Preoperative versus postoperative radiation risks and benefits for sarcoma

Table 2.2 American Joint Committee on Cancer (AJCC) System for Staging Malignant Bone Tumors

Table 2.3 American Joint Committee on Cancer (AJCC) System for Staging Soft Tissue Sarcomas

Fig. 2.2 Description of surgical margins. (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

E. Chromosomal Translocations (Table 2.5)

Table 2.5 Common Tumor Chromosomal Translocations

1. Osteoid osteoma (Figs. 2.3, 2.4, 2.5)

Fig. 2.3 High-power view of nidus showing osteoblastic activity with occasional blood vessel and giant cells. (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

Fig. 2.4 Osteoid-osteoma. Low-power view with the nidus (right) and the reactive bone and remnants of the cortex (left).

Fig. 2.5 The nidus under high power has a disorganized pattern of woven bone with prominent osteoblastic rimming or palisading and benign fibrovascular stroma. Several large osteoclasts are present.

• Demographic: young patients (ages 5–30 years), male-to-female ratio = 2:1

2. Osteoblastoma (Figs. 2.6, 2.7, 2.8, 2.9)

• Demographic: young (ages 10–30 years), male-to-female ratio = 2:1

• > 2 cm

• Presentation: dull, aching pain not relieved by NSAIDs

• Locations: posterior elements of spine, proximal humerus, femur, tibia, hip, mandible

a. May be blastic or lytic

Fig. 2.6 Sagittal magnetic resonance imaging (MRI) of a T10 pedicle lesion. (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

Fig. 2.7 The pedicle is missing in a 12-year-old girl. (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

Fig. 2.8 A cystic pedicle lesion at T10 in a 12-year-old. (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

Fig. 2.9 Osteoblastoma with a chaotic arrangement of woven bone, prominent osteo-blasts, and bland cells without mitoses.

3. Myositis ossificans (Figs. 2.10, 2.11, 2.12)

• Reactive process typically caused by trauma, characterized by proliferation of fibroblasts, cartilage, bone within muscle.

• Demographic: ages 15–35 years, males > females

• Presentation: pain, swelling, decreased range of motion, increasing in size over several months

• Locations: muscles surrounding diaphysis of long bones (quadriceps, brachialis, gluteal muscles)

• Imaging: peripheral mineralization with central lucent area, not attached to bone; may initially be only periosteal reaction

a. Differential diagnosis: extraskeletal or parosteal osteosarcoma

• Histology: woven bone in zonal pattern with mature bone at periphery and immature fibrous tissue at center; may be confused with osteosarcoma

Fig. 2.10 Dense myositis ossificans in 22-year-old head-injured patient. (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

Fig. 2.11 Computed tomography (CT) of the proximal thigh in a 22-year-old man. (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

Fig. 2.12 In myositis ossificans, centrally, woven bone and abundant fibrovascular tissue is found. This zonation (peripheral well-defined bone and central poorly defined woven bone) is characteristic of myositis ossificans.

• Treatment: observation, repeat radiographs; may excise when lesion is mature (typically 6–12 months)

4. Melorheostosis (Fig. 2.13)

• Rare disorder of new periosteal bone formation on surface of multiple bones

• Demographic: discovered at age < 40 years

• Presentation: significant pain, decreased range of motion (ROM)

• Location: long bones, feet

• Imaging: “dripping candle wax” with wavy appearance, can involve joint

• Treatment: can excise hyperostotic areas to improve ROM or observe if asymptomatic

B. Benign Reactive Lesions of Bone

1. Aneurysmal bone cyst (Table 2.6, Figs. 2.14, 2.15, 2.16)

• Benign, locally aggressive lesion of bone

• May be primary or in association with other tumors [giant cell tumor (GCT), chondroblastoma, chondromyxoid fibroma, fibrous dysplasia (FD)]

• Genetics: upregulation of ubiquitin-specific protease (USP)-6

• Demographic: age < 20 years

• Presentation: pain, swelling

• Location: distal femur, proximal tibia, pelvis, posterior elements of spine (25%)

• Imaging: eccentric, lytic, expansile area of destruction in metaphysis, typically with rim of new bone surrounding lesion

a. Expands wider than physis

b. MRI: fluid–fluid levels

c. Differential: UBC, telangiectatic osteosarcoma

• Histology: cavernous blood-filled spaces, no endothelial lining, + giant cells, septations

• Treatment: curettage, bone grafting

• Risk of recurrence

• Factors leading to increased risk of recurrence: young age, open physes, high stage, positive margin at time of excision

2. Unicameral bone cyst (Table 2.6, Figs. 2.17 and 2.18)

• Demographic: age < 20 years

• Presentation: pain, usually after fracture from minor trauma

Fig. 2.13 Melorheostosis. X-ray showing thick and wavy bone consistent with melorheostosis.

Table 2.6 Aneurysmal Bone Cyst Versus Unicameral Bone Cyst

Fig. 2.14 Subtle tibial cortical lesion in a 16-year-old boy. (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

Fig. 2.15 Coronal MRI showing septations and fluid–fluid levels. (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

Fig. 2.16 Aneurysmal bone cyst (ABC) is composed of large blood-filled spaces surrounded by fibrous tissue, often with bony spicules. The spaces are not lined by endothelial cells, which are seen in vascular structures.

1. High-grade intramedullary osteosarcoma (Figs. 2.19, 2.20, 2.21, 2.22, 2.23, 2.24, 2.25)

• High-grade, intermediate-grade, low-grade variants

a. High-grade variants: osteoblastic, fibroblastic [differentiate from malignant fibrous histiocytoma (MFH)], chondroblastic (differentiate from chondrosarcoma), telangiectatic (differentiate from ABC), small cell (differentiate from Ewing’s sarcoma), giant cell rich (differentiate from giant cell tumor of bone)

b. No difference in prognosis between high-grade variants

c. All grades may be intramedullary or surface lesions.

Fig. 2.17 Proximal humerus demonstrating a fracture through a well-marginated, lucent cyst in the metaphysis.

Fig. 2.18 Unicameral bone cyst (UBC) with a thin lining of fibrous tissue and some vessels. There is usually no reactive bone production as seen in an ABC.

Fig. 2.19 (a) Parosteal osteosarcoma arises from the surface of the bone (usually the posterior femur). (b) Periosteal osteosarcoma arises from the surface with mineralization and a sunburst pattern. (c) Telangiectatic osteosarcoma arises from the metaphysis as a lytic mass, with areas of hemorrhage that create fluid–fluid levels on imaging. (d) High-grade intramedullary osteosarcoma is the most common primary sarcoma of bone and arises from the intramedullary canal as a lytic and blastic lesion with cortical destruction and soft tissue mass.

Fig. 2.20 Intramedullary osteosarcoma. Anteroposterior (AP) X-ray demonstrating a lytic and blastic lesion of the distal femur with the suggestion of a soft tissue mass.

Fig. 2.21 Lateral X-ray of the lesion in Fig. 2.20.

Fig. 2.22 Axial T2 MRI showing soft tissue extension of the intramedullary in Fig. 2.20.

Fig. 2.23 Bone scan showing increased signal in the distal femur of the lesion in Fig. 2.20; used to evaluate for skip lesions or metastatic disease.

2. Telangiectatic osteosarcoma (Figs. 2.26 and 2.27)

• Rare variant of osteosarcoma containing cavernous blood-filled spaces

• Demographics: ages 10–30 years

• Location: knee, proximal femur, proximal humerus—same as ABC

• Imaging: destructive, lytic lesion; MRI demonstrates fluid–fluid lesions

a. Differential: ABC

Fig. 2.24 Osteosarcoma, high grade, is composed of pleomorphic cells with hyperchromatic nuclei producing scattered woven bone trabeculae.

Fig. 2.25 Osteosarcoma, low power, replacing the marrow cavity and extending into the cortical vascular spaces. Remnants of marrow lamellar bone trabeculae are seen within the tumor.

Fig. 2.26 Axial CT showing a lytic, destructive lesion, found in telangiectatic osteosarcoma.

Fig. 2.27 Coronal CT of the lesion in Fig. 2.26.

Fig. 2.28 Classic sunburst pattern with radiating spicules of bone formation.

Fig. 2.29 Classic sunburst pattern with radiating spicules of bone formation.

Fig. 2.30 Osteosarcoma photomicrograph demonstrating chondroid matrix. (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

4. Periosteal osteosarcoma (Figs. 2.28, 2.29, 2.30)

• Demographic: ages 10–20 years

• Presentation: pain

• Location: diaphysis of long bones (femur/tibia)

• Imaging: sunburst lesion overlying cortical depression

• Histology: typically high grade, chondroblastic matrix, osteoid

• Treatment: neoadjuvant chemotherapy, wide resection, adjuvant chemotherapy

D. Benign Cartilage Producing Lesions

1. Periosteal chondroma

• Benign cartilage tumor on surface of bone

• Location: 50% proximal humerus, femur

• Imaging: eccentric, cortically based lesion eroding the underlying cortex, producing a saucer-like defect

a. Differential diagnosis: osteochondroma (but without stalk) or myositis ossificans

• Histology: chondroid matrix and lacunae with multiple chondrocytes

• Treatment: marginal excision including underlying cortex

2. Enchondroma (Figs. 2.31, 2.32, 2.33, 2.34)

• Benign cartilage lesion in medullary cavity

Fig. 2.31 Dense calcified lesion of proximal humerus (enchondroma). (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

Fig. 2.32 Calcified lesion on coronal CT scan (enchondroma). (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

Fig. 2.33 Heterogeneous calcified lesion on axial MRI (enchondroma). (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

• Demographic: age > 20 years

Fig. 2.34 Enchondroma abutting the cortex. There is no invasion into the bone but rather a “pushing” border against the bone. [Histo 4.2 (100×).]

b. Enchondromas of the hand generally treated surgically after fracture to prevent repeat fractures (Fig. 2.35)

• Syndromes

a. Ollier’s: multiple enchondromas, particularly unilateral, 30% lifetime risk of malignancy

b. Maffucci’s: multiple enchondromas, associated soft tissue hemangiomas, increased risk of visceral malignancies, 100% risk of transformation to chondrosarcoma

3. Osteochondroma (Figs. 2.36, 2.37, 2.38)

• Benign surface lesions (35% benign lesions), typically associated with tendon insertions

• May be single or multiple (multiple hereditary exostosis)

• Demographic: ages 10–30 years

• Presentation: incidental or painful (if overlying bursae, irritating tendon, joint capsule)

• Location: metaphyseal—knee, proximal femur, proximal humerus

• Imaging: surface lesion with cortex of the lesion and underlying cortex continuous with medullary cavity

a. Sessile versus pedunculated

b. Cartilage cap grows away from physis

c. Stops growing with skeletal maturity

d. Obtain MRI or CT to evaluate thickness of cartilaginous cap and presence of soft tissue mass if suspicious for chondrosarcoma in an adult with an enlarging lesion.

• Histology: similar to that of enchondroma

a. If cartilage cap > 2 cm, raise concern about conversion to chondrosarcoma

b. Hyaline cartilage cap with cortical and trabecular bone comprising stalk, endochondral ossification

• Treatment: observation (asymptomatic) versus excision (soft tissue irritation)

a. New change in pain should be worked up to address concern about conversion to chondrosarcoma (order an MRI).

Fig. 2.35 (Figure Enchondroma) Fracture through an enchondroma of the proximal phalanx.

Fig. 2.36 (Figure Osteochondroma 1) Benign-appearing surface lesion extending from the medullary cavity of the humerus

Fig. 2.37 The deep portion of the cartilage cap of an osteochondroma with endochondral ossification and deposition of woven bone on the surface of cartilage cores. This field is identical to that of a normal epiphyseal growth plate because the cartilage cap is really a displaced epiphyseal growth plate. [Histo 80.1 (400×).]

Fig. 2.38 The cartilage cap of an osteochondroma is covered by the dense collagenous perichondrium. Histologically the two diagnostic features are the presence of the perichondrium covering the hyaline cartilage cap and the direct communication of the bony stalk with the marrow space of the parent bone. There is no cortex separating the two. [Histo 80.11 (40×).]

a. Multiple hereditary exostosis (Fig. 2.39)

◦ Gene: EXT1, EXT2, EXT3, autosomal dominant

♦ Mutation affects prehypertrophic chondrocytes of the growth plate

◦ 5–10% develop secondary chondrosarcoma, EXT1 > EXT2

◦ Primarily sessile lesions large in size

◦ May cause progressive skeletal deformities including short stature, limb-length discrepancies, valgus deformity or knee and ankle, asymmetry of pectoral and pelvic girdle, bowing of radius with ulnar deviation, subluxation of radiocapitellar joint

Fig. 2.39 (a) Anteroposterior X-ray of the forearm showing a typical exophytic lesion with classic ulnar shortening and secondary radial bowing. (b) Lateral forearm view showing a large exostosis extending into the flexor volar compartment. (From Conrad EU. Orthopaedic Oncology: Diagnosis and Treatment. New York: Thieme; 2008. Reprinted with permission.)

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