Evaluation of pediatric musculoskeletal tumors (Derleme)

(1)

Corresponding author: Bülent Erol

Department of Orthopaedics and Traumatology The Hospital of University of Marmara

Tophanelioglu Caddesi, No: 13/15 Altunizade/Istanbul

E-mail: bulerol@hotmail.com Tel:+90 216 325 45 82 Fax: 216 325 45 82

Marmara Medical Journal 2004;17(3);140-145

REVIEW

EVALUATION OF PEDIATRIC MUSCULOSKELETAL TUMORS

Bülent Erol, Murat Bezer, Osman Güven

Department of Orthopaedics and Traumatology,School of Medicine, Marmara University,Istanbul, Turkey

ABSTRACT

A wide range of musculoskeletal tumors occurs in the pediatric population. Physicians should be aware of the clinical and radiographic manifestations of these tumors in order to provide timely specialist referrals so that early diagnosis and treatment can be achieved. Improvements in diagnosis and treatment have increased survival for many children with malignant musculoskeletal tumors.

Keywords: Pediatrics, Musculoskeletal tumors

PEDİATRİK MUSKÜLOSKELETAL TÜMÖRLER

ÖZET

Pediatrik popülasyonda geniş bir yelpazeyi içeren musküloskeletal tümörler görülebilir. Bu tümörlerin ilgili uzmanlara zamanında danışılabilmesi ve dolayısıyla erken tanı ve tedavinin sağlanabilmesi için, doktorların çocukluk çağı musküloskeletal tümörlerinin klinik ve radyografik bulguları hakkında bilgi sahibi olmaları gerekir. Tanı ve tedavideki ilerlemeler habis musküloskeletal tümörlü çocukların çoğunda sağkalım oranını arttırmıştır.

Anahtar Kelimeler: Pediatri, Musküloskeletal tümörler

INTRODUCTION

Pediatric musculoskeletal tumors are uncommon,

and when they occur, are usually benign. Early

detection of a malignant musculoskeletal tumor

may not only make the difference between life

and death, but also may allow for successful limb

salvage surgery rather than amputation of the

limb. The primary bone and soft tissue tumors of

childhood can be classified based on their tissue

origin (Table I).

Table I: Classification of pediatric musculoskeletal tumors based on tissue of origin

Bone tumors

Bone origin; osteoid osteoma, osteoblastoma, osteosarcoma

Cartilaginous origin; osteochondroma, chondroblastoma, chondromyxoid fibroma, enchondroma, periosteal chondroma

Fibrous origin; nonossifying fibroma, fibrous dysplasia, osteofibrous dysplasia, desmoplastic fibroma

Miscellaneous; unicameral bone cyst, aneurysmal bone cyst, giant cell tumor Langerhans cell histiocytosis, Ewing sarcoma

Musculoskeletal manifestations of leukemia Bone lymphomas

Metastatic tumors; neuroblastoma, retinoblastoma, hepatoblastoma

Soft tissue tumors

Vascular tumors; hemangioma, vascular malformations

Nerve origin; neurolemmoma, neurofibroma, malignant peripheral nerve sheath tumor Fibrous origin; fibromatosis, fibrosarcoma

Muscular origin; rhabdomyosarcoma Miscellaneous; synovial sarcoma Primitive neuroectodermal tumors Ganglion and synovial cyst

(2)

Marmara Medical Journal 2004;17(3);140-145 Bülent Erol, et al.

Evaluation of Pediatric Musculoskeletal Tumors

EVALUATION

Clinical evaluation

A thorough evaluation of the history of the patient

and physical examination are the basis for

determining the correct diagnosis and therapy.

Children with a musculoskeletal tumor usually

present with pain, mass, pathologic fracture, or

incidental findings on radiographs (Table II). The

physical examination should include

neurovascular examination of the affected

extremity, range of motion of the adjacent joint,

and gait pattern of the patient. The size,

consistency, and mobility of a mass should be

evaluated. For soft tissue masses, small (< 5cm),

superficial, soft, and movable masses are usually,

but not always, benign. On the other hand, large

(> 5cm), deep, firm, fixed, and tender masses raise

suspicion of malignancy and are less commonly

benign.

Table II: Clinical presentations of pediatric musculoskeletal tumors 1) Pain

▪Duration ▪ Localization ▪ Severity ▪ Character

▪ Relief and how obtained 2) Mass

▪ Duration ▪ Size ▪ Consistency ▪ Mobility

3) Pathologic fracture spectrum from microfractures to displaced fractures ▪ Prior symptoms and signs

▪ Mechanism of fracture ▪ Characteristics of fracture 4) Incidental radiographic findings ▪ Prior symptoms and signs ▪ Why radiograph obtained

Most musculoskeletal tumors occur more

commonly in boys than in girls. The gender of the

patient, however, usually does not play a

significant role in formulating the differential

diagnosis. Ewing sarcoma is unusual because it

shows a race association; it is very prevalent in

whites and is rarely seen in African-Americans.

The age of the patient is important in establishing

a differential diagnosis, because certain tumors

tend to occur in certain age groups (Table III).

Table III: Peak age of common pediatric musculoskeletal tumors

Age (years) Benign Malignant

0-5 Langerhans cell histiocytosis Fibrosarcoma Osteomyelitis Metastatic tumors Leukemia Ewing sarcoma --- 5-10 Unicameral bone cyst Osteosarcoma Aneurysmal bone cyst Rhabdomyosarcoma Nonossifying fibroma

Fibrous dysplasia Osteoid osteoma

Langerhans cell histiocytosis

--- 10-20 Fibrous dysplasia Osteosarcoma Osteoid osteoma Ewing sarcoma Fibroma Chondrosarcoma Aneurysmal bone cyst Rhabdomyosarcoma

(3)

Radiographic evaluation

After careful history and physical examination,

looking at the imaging studies of the lesion is the

next step in the evaluation. Plain radiographs give

the most detailed information about skeletal

lesions. Plain radiographs, at least in two views

(anteroposterior and lateral), showing the entire

lesion are necessary. Thirty to 40% of a bone must

be destroyed before changes can be seen in plain

radiographs. It is often difficult to see soft tissue

tumors and soft tissue extension from bony

neoplasms with plain radiographs. It is useful to

ask some questions when evaluating plain

radiographs of bony lesions: Where is the lesion

located in the bone? What is the lesion doing to

the bone? What is the bone doing to the lesion?

What is the periosteal response

1

_?

The anatomic location of bony lesions should be

identified as epiphyseal, metaphyseal, or

diaphyseal, and central or eccentric (Table IV).

The lesion may be destroying or replacing the

existing bone. Bone destruction can be described

as geographic, moth-eaten, and permeative (Fig.

1).

Although none of these features are

pathognomonic for any specific neoplasm, the

type of destruction may suggest a benign or a

malignant process. Geographic bone destruction

typifies slow-growing, benign lesions, whereas

moth-eaten (i.e., characterized by multiple, small,

often clustered lytic areas) and permeative (i.e.,

characterized by ill-defined, very small oval

radiolucencies or lucent streaks) types of bone

destruction mark rapidly growing, infiltrating

tumors

2

_{. The response of the bone to the}

neoplastic process involves the response of the

adjacent cortex and periosteum

3

_{. The lesion may}

be contained by the cortex or “walled off” by

dense sclerotic bone, implying a very

slow-growing or static lesion, or it may destroy the

cortex and form a soft tissue mass, mostly

indicating an aggressive neoplastic process. Like

the pattern of bone destruction, the pattern of

periosteal reaction is an indicator of the biologic

activity of a lesion. Although no single periosteal

response is unique for a given lesion, a continuous

periosteal reaction indicates a long-standing

(slow-growing) benign process. An interrupted

periosteal reaction, on the other hand, is

commonly seen in malignant tumors; in these

tumors, the periosteal reaction may appear in a

sunburst (“hair-on-end”) or onion-skin

(lamellated) pattern. A reactive periosteal cuff at

the periphery of the tumor, a Codman’s triangle,

also may form (Fig. 2).

(4)

Evaluation of Pediatric Musculoskeletal Tumors Table IV: Common locations of pediatric bone tumors Epiphysis Pelvis

Chondroblastoma Ewing sarcoma Brodie’s abscess of the epiphyses Osteosarcoma

Giant cell tumor Osteochondroma Fibrous dysplasia Metastasis

Metaphysis Fibrous dysplasia

Any tumor Anterior elements of spine

Diaphysis (FAHEL) Langerhans cell histiocytosis

Fibrous dysplasia Leukemia Osteofibrous dysplasia Metastatic Langerhans cell histiocytosis Giant cell tumor Ewing sarcoma Posterior elements of spine Leukemia, lymphoma Aneurysmal bone cyst Occasional diaphyseal Osteoblastoma Osteoid osteoma Osteoid osteoma Unicameral bone cyst Rib

Multiple Fibrous dysplasia

Leukemia (metastasis) Langerhans cell histiocytosis Multiple hereditary exostoses Ewing sarcoma

Langerhans cell histiocytosis Metastasis Polyostotic fibrous dysplasia

Enchondromatosis

If the radiographs reveal a lesion that has a

potential for malignancy or do not confirm a

specific diagnosis, further staging studies are

indicated. A magnetic resonance imaging (MRI)

and a computed tomography (CT) scan will serve

as the best imaging to further evaluate the lesion.

MRI best demonstrates the soft tissue anatomy

and intramedullary extension of the tumor. The

ability of MRI to produce images of the body in

three planes (axial, sagittal, coronal) provides a

significant advantage in defining the extent of

many tumors (Fig.3A-B)

4

_{. MRI remains the}

modality of choice for staging, for evaluating

response to preoperative chemotherapy, and for

long-term followup of most bone and soft tissue

sarcomas. CT can demonstrate bone destruction

and mineralization (calcifications or bone

formation within the tumor), and is particularly

helpful for bone tumors involving axial skeleton

(i.e., pelvis, spine) (Fig.4). A total body

radionuclide bone scan will evaluate the biologic

activity of the primary bone lesion and search for

other lesions within the skeletal system. It may be

indicated to locate obscure lesions such as osteoid

osteoma or stress fracture.

Fig 3A-B: (A) The coronal T2-weighted image of the proximal leg shows an expansile lesion in the proximal fibula, replacing the bone marrow. Increased signal, representing edema is also seen in the muscles surrounding the mass (arrow). (B) The axial T2-weighted image demonstrates complete replacement of the marrow with a large soft tissue component surrounded by a thin layer of new bone formation. In addition, soft nodules (arrows) are seen outside the margin of bone formation. The diagnosis of this lesion is osteosarcoma.

(5)

Fig 4: The axial computed tomography image of the pelvis demonstrates destructive lesions in the right sacral alae and a lytic lesion in the right ilium. The diagnosis of this lesion is Non-Hodgkin’s lymphoma of bone.

Staging and biopsy

Staging of lesions that appear to be malignant is

required prior to biopsy. Staging includes a total

body bone scan, a CT scan of the chest, and a

MRI of the primary lesion (Table V). Based on

these studies, a biopsy can be planned to confirm

the diagnosis. Biopsy should be the last step in the

evaluation of a patient with a bone or soft tissue

sarcoma and should be performed following

completion of the radiographic staging and

preoperative consultation with the oncologist,

radiologist, pathologist, and surgeon. After

staging studies are completed, a differential

diagnosis can be formulated.

Table V: Current treatment principles of malignant bone tumors of childhood Staging of primary lesion and search for other lesions

Magnetic resonance imaging of the primary site including the joint above and below Total body radionuclide bone scan; to search for bone metastases and skip lesions Computed tomography of the chest; to search for lung metastases

Pediatric oncology consultation Incisional biopsy

Intraoperative frozen section

Bone marrow aspiration/biopsy for Ewing sarcoma Broviac placement for chemotherapy

Preoperative neoadjuvant chemotherapy (usually multiagent chemotherapy)

Repeat magnetic resonance imaging after chemotherapy and prior to definitive surgery Radiographic evaluation of the tumor response to chemotherapy (change in size of tumor, change in amount of tumor edema, involvement of neurovascular structures) Surgical planning

Surgery; excision of the tumor with wide surgical margins

Limb-salvage surgery; resection of the tumor with wide surgical margins and reconstruction. Currently, possible in most patients with extremity sarcoma Amputation

Histologic examination of resection specimen

Histologic evaluation of the tumor response to chemotherapy (> 90% tumor necrosis demonstrates good response)

Verification of wide surgical margins

Continued chemotherapy (adjuvant chemotherapy) after local control surgery

Usually same protocol with neoadjuvant chemotherapy if tumor response to chemotherapy is good Followup

(6)

The best biopsy method for a musculoskeletal

neoplasm depends on the differential diagnosis,

the location of the neoplasm, and the ability of the

pathologist to make a diagnosis on a sample of

tissue. A well-planned biopsy provides an

accurate diagnosis and facilitates treatment. On

the other hand, a poorly performed biopsy may

fail to provide a diagnosis and more importantly,

may have a negative impact on treatment options

and/or survival. Needle aspiration may provide

adequate tissue for a histologic diagnosis;

however, many oncologic surgeons prefer an open

incisional technique, which also provides

sufficient tissue for the multiple studies often

needed, including newer molecular diagnostics.

Incisional biopsy involves removing only a

portion of the tumor without contaminating the

surrounding soft tissue structures. A biopsy is best

accomplished at the institution that would perform

the definitive surgery if it becomes necessary

5,6

_.

REFERENCES

1. Enneking WF: Musculoskeletal tumor surgery. New York, Churchill Livingstone, 1983.

2. Madewell JE, Ragsdale BD, Sweet DE: Radiologic and pathologic analysis of solitary bone lesions. Part I: Internal margins. Radiol Clin North Am 1981; 19: 715-48.

3. Ragsdale BD, Madewell JE, Sweet DE. Radiologic and pathologic analysis of solitary bone lesions. Part II: Periosteal reactions. Radiol Clin North Am 1981; 19: 749-83.

4. Gillespy T III, Manfrini M, Ruggieri P, Spanier SS, Petterson H, Springfield DS. Staging of intraosseous extent of osteosarcoma: Correlation of preoperative CT and MR imaging with pathologic macroslides. Radiology 1988; 167: 765-67.

5. Simon MA, Biermann JS. Biopsy of bone and soft tissue lesions. J Bone Joint Surg 1993; 75A: 616-21.

6. Erol B, Dormans JP, States L, Pawel B. Tumors. In: Cramer KE, ed. Orthopaedic Surgery Essentials-Pediatrics. Philadelphia: Lippincott Williams & Wilkins, 2004: 250-270.