BONE TUMORS AND TUMOR-LIKE LESIONS
 

INFORMATION IMPORTANT FOR THE DIAGNOSIS OF BONE TUMORS

Age and gender: usually young, M:F = 2:1

Site: which bone

Location: where in the bone

Imaging: tumor and adjacent bone

Clinical: pain, response to aspirin, predisposing conditions

Histopathology: bone-forming, cartilage-forming, and fibrous/fibro-osseous

SITES OF BONE TUMORS

Axial Skeleton

Skull and facial bones

Jaw

Spine

Appendicular Skeleton

Long tubular bones

Hands and feet

LOCATION OF BONE TUMORS

Epiphysis

Benign: chondroblastoma, giant cell tumor

Malignant: rare

Metaphysis

Benign: giant cell tumor, osteoid osteoma, enchondroma, osteoblastoma, osteochondroma, nonossifying fibroma

Malignant: osteosarcoma, chondrosarcoma

Metaphyseal/diaphyseal junction

Benign: fibrous dysplasia, fibrous cortical defect, osteoid osteoma, chondromyxoid fibroma

Malignant: fibrosarcoma

Diaphysis

Benign: enchondroma, fibrous dysplasia

Malignant: Ewing’s sarcoma, chondrosarcoma, adamantinoma

IMAGING OF BONE TUMORS

Patterns of Bone Destruction

Benign: sclerotic, sharply defined margins

Malignant: moth-eaten and permeative growth patterns

Quality of Mineralized Matrix

Cortical vs Intramedullary

Cortical: osteoid osteoma, non-ossifying fibroma, osteofibrous dysplasia

Intramedullary: most common

CLASSIFICATION OF BONE TUMORS

Bone-forming Tumors

Benign: osteoma, osteoid osteoma, osteoblastoma

Malignant: osteosarcoma

Cartilage-forming Tumors

Benign: osteochondroma, chondroma, chondroblastoma

Malignant: chondrosarcoma

Fibrous and Fibro-osseous Tumors

Benign: fibrous cortical defect/non-ossifying fibroma, fibrous dysplasia

Malignant: fibrosarcoma, malignant fibrous histiocytoma

Miscellaneous Tumors

Benign: giant cell tumor

Malignant: Ewing’s sarcoma/PNET, myeloma, lymphomas, metastatic malignancies

BONE-FORMING TUMORS

Osteoma

Clinical features

40-50 yr. old, M:F = 2:1

Slow growing, bosselated, solitary

Skull and facial bones

Gardner’s syndrome - multiple lesions

No malignant potential

Radiographic features

Sharply circumscribed radiopaque mass protruding from the bone surface

Histology

Dense lamellar bone with no medullary component

Osteoid Osteoma vs Osteoblastoma

Clinical features

10-30 yr old for both, M:F = 2:1

OO OB

< 2cm > 2 cm

femur, tibia, humerus spine

pain relieved by aspirin no response

nidus w/ reactive border less reactive border

Histologic features

Randomly interconnecting trabeculae of woven bone prominently rimmed by osteoblasts

Intertrabecular vascular loose connective tissue

Clinical course

Complete surgical excision

Tend to recur with curettage or incomplete excision

Osteosarcoma (Osteogenic Sarcoma)

Clinical features

Most common primary bone malignancy excluding myeloma and lymphoma

75% < 20 yr. (10-25 yr. old)

Elderly (2nd peak), a/w Paget’s disease, bone infarcts, chronic osteomyelitis and radiation

Long bones at the knee, hip, shoulder

Metaphysis

Intramedullary, intracortical, or surface

Radiographic features

Osteoblastic vs osteolytic

Codman's triangle

Sun-burst appearance

Histologic types

Malignant cells and osteoid +/- woven bone

Osteoblastic, chondroblastic, fibroblastic, telangiectatic, small cell, giant cell

CARTILAGE-FORMING TUMORS

Osteochondroma (exostosis)

Clinical features

80% under age 20, around 10 yo

M:F ratio - 3:1

Metaphysis, distal femur, proximal tibia and humerus

Solitary (usually) vs multiple (osteochondromatosis)

Radiographic features

Mushroom shaped metaphyseal bony protuberance covered by cartilage, average size = 4 cm (1-20 cm)

Clinical course

Latent, usually asymptomatic

1% malignant transformation, especially hereditary syndrome

Chondromas

Clinical features

No sex predilection, 20-50 years of age

Slow growth; activated growth may produce pain

Location

Hands and feet, esp. proximal phalanges

Metaphysis

Enchondromas (most common) vs surface (subperiosteal or juxtacortical) chondromas

Solitary vs enchondromatosis (Ollier's disease and Maffucci's syndrome)

Radiographic features

Well circumscribed radiolucency (popcorn-like densities) surrounded by a thin rim of radiodense bone (O ring sign)

Histologic features

Lobules of benign hyaline cartilage with distinct lacunar spaces

Peripheral ossification and central calcification

Treatment and prognosis

Curettage with or without bone grafting

Malignant transformation to chondrosarcoma in pts with ….

Ollier's disease : enchondromatosis

Maffucci's syndrome : enchondromatosis + soft tissue hemangiomas

Chondroblastoma

Clinical features

5-25 yrs old.

Epiphysis, knee and proximal humerus

Radiographic features

Well-defined epiphyseal radiolucency with spotty calcification

Histologic features

Primitive chondroblasts

Chicken-wire pattern of calcification

Osteoclast-type giant cells

Chondrosarcoma

Clinical aspects

2nd most common matrix-producing primary bone malignancy (half of osteosarcoma cases)

> 40 yrs

Axial skeleton (pelvis, shoulder, ribs)

Radiographic features

Radiolucency with scalloped border and flocculent matrix calcification

Low grade: less radiolucent, reactive thickening of cortex

High grade: more radiolucent, eroded thin cortex

Histologic features

Intramedullary and juxtacortical

Conventional (hyaline and/or myxoid), clear cell, dedifferentiated, and mesenchymal

Grading (1, 2, 3)

Broad "pushing fronts"

Treatment and prognosis

Wide excision vs amputation

Additional chemo for mesenchymal and dedifferentiated chondrosarcomas

Metastasis to lungs and bones

FIBROUS & FIBRO-OSSEOUS TUMORS

Fibrous Cortical Defect (0.5 cm) & Nonossifying Fibroma (5-6 cm)

Etiology

Developmental defect rather than neoplasms

Clinical features

Adolescence

Knee bones, metaphyseal

Fibrous cortical defect: asymptomatic incidental finding, usually self-healing

Nonossifying fibroma: pathologic fracture

Radiographic features

Sharply demarcated radiolucency in cortex

A thin rim of sclerotic reactive bone on periphery

Histologic features

Storiform or pinwheel pattern of spindle cells (fibroblasts)

Multinucleated giant cells or clusters of foamy histiocytes

Fibrous Dysplasia

Etiology

Localized developmental arrest

Sites

Monostotic: ribs, femur, tibia

Polyostotic: femur, skull, tibia

Clinical signs

Early adolescence, three types

Monostotic (70%): minimal Sx to fracture

Polyostotic w/o (27%) or w/ endocrinopathies (McCune-Albright's syndrome) (3%): fractures and deformities - "shepherd crook" proximal femur; rare malignant transformation to sarcomas

Radiographic Features

Well-defined intramedullary lesion

Ground glass appearance

Histologic Features

Curvilinear trabeculae of woven bone (Chinese characters)

Lack of osteoblastic rimming

Intertrabecular fibroblastic proliferation

Fibrosarcoma & Malignant Fibrous Histiocytoma (MFH)

Malignant fibroblastic collagen-producing sarcomas of bone

MISCELLANEOUS TUMORS
 

Ewing’s Sarcoma and Primitive Neuroectodermal Tumor (PNET)

Pathogenesis

t(11;22) (85%), t(21;22) (5-10%), t(7;22) (<1%)

Fusion of EWS gene (22q12) and FL-1 gene (11q24) – chimeric transactivator (MIC2/CD99) of c-myc gene

ES is a less differetiated form of PNET

Clinical aspects

5-15 yr. old

Diaphysis and medullary cavity of long tubular bones (femur, tibia, humerus, fibula), pelvis, ribs, vertebra, etc

S&S mimic infection

Radiographic features

Onion skin pattern of periosteal reactive bone

Intramedullary lytic lesion of diaphysis

Histologic features

Malignant small round cell tumor of bone

Without neural differentiation – Ewing’s sarcoma

With neural differentiation – PNET

Prognosis and treatment

Chemotherapy and surgery with or without radiation

Prognosis was poor (5-15% 5-yr. survival), now much better with effective chemotherapy (75%)

Giant Cell Tumor of Bone

Clinical features

20-50 yrs old

Female > male: the only bone tumor with female prevalence!

Arthritic symptoms of knee

Predominantly benign but locally aggressive

Site

around the knee

Epiphyseal and metaphyseal in adults; metaphyseal in adolescents

Radiographic features

Large, pure lytic, and eccentric lesion

Thin shell of reactive bone

Histologic features

Mononuclear stromal cells and multinucleated giant cells with identical nuclear features

Necrosis, hemorrhage, and reactive bone formation

Clinical course

Locally aggressive: 30-50% recurrence after curettage, 7% for en bloc excision

Rarely malignant: 5-10% metastatic, most common to lung

No radiation therapy (often induces malignant transformation)

Metastatic tumors to the skeleton

Most common form of skeletal malignancy!

Usually multiple

Kidney and thyroid - frequently solitary

Pathways of spread

Direct extension

Angiolymphatic dissemination

Intraspinal seeding (Batson plexus of veins)

Most common metastatic cancers

Adults: thyroid, breast, lung, kidney, and prostate

Children: neuroblastoma, Wilms’ tumor, osteosarcoma, Ewing sarcoma, and rhabdomyosarcoma

Sites

Axial skeleton (vertebral column, pelvis, ribs, skull, and sternum)

Proximal femur

Humerus

Radiographic features

Osteoclastic lesion: kidney, lung, GI, melanoma

Osteoblastic lesion: prostate

Mixed lytic and blastic: most of the metastases

 

THE END