Imaging of Bone Tumors Dr Bashar Adnan Introduction

Imaging of Bone Tumors Dr. Bashar Adnan

Introduction � Forms 0. 2% of human tumor burden � Primary malig bone tumors make 1% of all malignant tumors � Most have male predominance except GCT, ABC. � Most common malignant tumour is secondary metastatic deposits, mostly from

X-rays - the question need to ask: � (1) � (2) � (3) � (4) � (5) Location of the lesion Extent of the lesion What is the lesion doing to the bone? What is the bone doing to the lesion? Hint as to its tissue type / matrix

A. Location � Location and age of patient most important parameters in classifying a primary bone tumor. � Simple to determine from plain radiographs.

Location

Location in Longitudinal Plane � EPIPHYSEAL ◦ Chondroblastoma ◦ Clear cell chondrosarcoma ◦ Giant cell tumor ◦ Aneurysmal bone cyst ◦ Geode (subchondral cyst) ◦ Infection ◦ Eosinophilic granuloma � METAPHYSEAL ◦ Nonossifying fibroma (close to growth plate) ◦ Chondromyxoid fibroma (abutting growth plate) ◦ Solitary bone cyst, ABC, GCT ◦ Osteochondroma ◦ Brodie abscess ◦ Osteogenic sarcoma, chondrosarcoma � DIAPHYSEAL ◦ Adamantinoma ◦ Leukemia, Lymphoma, Reticulum cell sarcoma ◦ Ewing sarcoma ◦ Metastasis ◦ Osteoblastoma/ osteoid osteoma ◦ Nonossifying fibroma

Location in Transverse Plane � � Central: Enchondroma Eccentric: GCT, CMF, osteosarcoma Cortical: osteoid osteoma, NOF Parosteal: osteochondroma, parosteal osteosarcoma

Specific Location BONE TUMOR SBC ABC, GCT, Osteosarcoma Enchondroma Osteochondroma Chondroblastoma Ewing’s Adamantinoma Myeloma Fibrous dysplasia Osteoid osteoma Chordoma Ivory osteoma Chondromyxoid fibroma Chondroblastoma Osteoblastoma COMMONEST SITE Proximal humerus > prox. Femur Lowerend femur > upper end tibia Metaphysis of small bones of hand & feet Distal femur> prox. Tibia > prox. Humerus Proximal humerus> prox femur Femur > fibula > tibia Mandible > tibia Vertebra Ribs > Upper femur > Tibia > lower femur Femur > tibia Sacrum > clivus (spheno occipital) > anterior vertebral body Frontal sinus Tibia > femur Pelvis > femur Posterior spine

Cysts and cyst like lesions of bone

B: What is the lesion doing to the bone? Patterns of bone destruction: � Lytic • GEOGRAPHIC Well-defined smooth / irregular margin Short zone of transition • PERMEATIVE Poorly demarcated lesion imperceptibly merging with uninvolved bone Long zone of transition • MOTHEATEN Areas of destruction with ragged borders. Less well defined / demarcated lesional margin Longer zone of transition � Sclerotic

MARGIN � Margin between tumor and native bone is visible on the plain radiograph. � Slowly progressive process is “walled-off” by native bone, producing distinct margins. � Rapidly progressive process destroys bone, producing indistinct margins.

Radiographic Margins � Margin types 1 A, 1 B, 1 C, 2, and 3 ◦ least aggressive 1 A, to most aggressive 3 � Aggressive lesions destroy bone. � Aggressiveness increases likelihood of malignancy. ◦ BUT, not all aggressive processes are malignant. ◦ AND, not all malignant diseases are aggressive.

Margins: 1 A, 1 B, 1 C A well circumscribed lesion with a narrow zone of transition increasing aggressiveness

1 A: sclerotic margin � simple cyst (UBC) � enchondroma � FD � chondroblastoma � GCT � chondrosarcoma (rare) � MFH (rare)

1 B: well-defined, non-sclerotic � GCT � enchondroma � chondroblastoma � myeloma, metastatsis � CMF � FD � chondrosarcoma � MFH

1 C: lytic, ill-defined margins � chondrosarcoma � MFH � osteosarcoma � GCT � metastasis � infection � EG � lymphoma

2: “motheaten” � myeloma, metastases � infection � EG � osteosarcoma � chondrosarcoma � lymphoma Multiple scattered holes that vary in size & seem to arise separately

3: “permeative” � Ewing � EG � infection � myeloma, metastasis � lymphoma � osteosarcoma Poorly demarcated from normal, numerous elongated holes/slots in cortex, run parallel to long axis of bone

B. Reaction of bone to tumor � Limited � Rate responses of bone Destruction: lysis (lucency) Reaction: sclerosis Remodeling: periosteal reaction of growth determines bone response ◦ slow progression, sclerosis prevails ◦ rapid progression, destruction prevails

Periosteal Reaction � Periosteal reaction must mineralize to be seen on X ray ( 10 days – 3 weeks) � Configuration of periosteal reaction ◦ ◦ Nature of inciting process Intensity Aggressiveness Duration

Periosteal Reaction � Thick, uninterrupted ◦ long standing process, often non-aggressive �stress fracture �chronic infection �osteoid osteoma � Spiculated, lamellated ◦ aggressive process ◦ tumor likely

Codman Triangle periosteal reaction Codman Triangle advancing tumor margin destroys periosteal new bone before it ossifies tumor

Sunburst Appearance

C: Tumor Matrix � “Matrix” is the internal tissue of the tumor � Most tumor matrix is soft tissue in nature. ◦ Radiolucent (lytic) on x-ray � Cartilage matrix ◦ calcified rings, arcs, dots (stippled) ◦ enchondroma, chondroblastoma, chondrosarcoma � Ossific matrix ◦ osteosarcoma

Osteochondroma �Exostosis: well defined bony projection growing away from physis �Cartilage maybe calcified if lesions are large / malignant change

Osteoid osteoma Nidus: a tiny radiolucent area � � � If in diaphysis surrounded by dense bone and thickened cortex Metaphysis less cortical thickening Double density sign on bone scan – increased uptake in nidus and decreased uptake in reactive sclerotic zone (also seen in Brodie’s abcess) Lytic nidus surrounded by sclerotic bone in CT Centre of nidus may be calcified

Osteoblastoma � Well demarcated osteolytic lesion sometimes containing flecks of calcification � Less reactive bone than osteoid osteoma � Bone scan - intense activity

Simple bone cyst � � � Cystic radiolucency on the diaphysial side of the growth plate Cortex may be thinned and bone expanded with well defined thin sclerotic margin May have pseudo-loculated appearance secondary to irregular cortical thinning and thin septal ridges Falling fragment sign typical and the lesion is never wider than epiphysial plate Bone scan cold or minimal activity unless fractured

Aneurysmal bone cyst � Gross honey comb lesion � Often eccentrically placed � Does not extend to the joint (unlike GCT) � Warm to hot on bone scan

Giant cell tumor Usually well defined geographic lytic lesion in the epiphysis/metaphysis extending up to the joint surface without marginal sclerosis � Junction with normal bone often poorly defined � Cortex thinned and sometimes ballooned � Bone scan warm to hot �

Fibrous cortical defect � Margin well defined, sometimes scalloped and often sclerosed

Non-ossifying Fibroma Geographic Well marginated Multilocular appearance Inter cortical osteolysis - single or multiple bubble like areas

Fibrous Dysplasia � Ground glass appearance typical � Shepherds crook deformity of proximal femur � Variable appearance with expansion of cortex

Enchondroma � Scalloped erosions on endosteal surface � May have flecks of calcification

Chondromyxoid fibroma � � � Rounded or oval rare area Usually eccentrically placed May cross the growth plate Sharp outline and sclerotic rim Scalloped margin and thin cortex

Chondroblastoma � � Well defined area of rarefaction eccentrically placed in the epiphysis or across the growth plate No reaction in surrounding bone 50% show central calcification, 50% show linear periosteal reaction Bone scan increased uptake at margins

Synovial Chondromatosis � Multiple loose bodies

Chordoma Large osteolytic lesion in the midline � May contain flecks of calcification � Marked bone destruction �

Brown Tumor � Diffuse osteopenia with multiple osteolytic lesions dispersed throughout skeleton.

Adamantinoma � Characteristic honey comb appearance in diaphysis � Cortical thinning with expansion

Hemangioma � Vertical striations without bone expansion and coarse trabecular appearance (corduroy appearance)

Eosinophillic granuloma � � � Mottled lytic defect usually no sclerotic rim May destroy cortex Usually endosteal or periosteal reaction Lesions in flat bones and ribs appear punched out May appear loculated due to sparing of large trabeculae Spinal lesions- collapse (vertebra plana), which may heal

Ewing’s sarcoma Mottled or moth eaten lesion diffusely involving bone � Lytic destruction common, often the cortex is perforated � Onion skin appearance- layers of periosteal new bone are said to be characteristic � May form Codman’s triangle �

Osteosarcoma � � � Variable with combination of bone destruction and bone formation Sun ray spicules/ sun burst appearance and Codman’s triangle may be evident Cortical breach common Adjacent soft tissue mass Joint space rarely involved ◦ 25% Lytic, 35% Sclerotic, 40% Mixed � Telangiectatic type- purely lytic

Chondrosarcoma � Variable appearance with 60 - 70% have calcification and 50% have sub periosteal new bone � May be a large cystic lesion with cortical destruction and central calcification, endosteal scalloping and cortical expansion; annular, punctate or comma shaped calcification

Fibrorosarcoma � Bone often mottled or moth eaten with extension into soft tissue � Osteolytic lesion may be surrounded by reactive bone � Destructive appearance radiologically � Usually little periosteal reaction

Metastatic bone disease � Osteolytic commonest - cortical destruction with little or no periosteal reaction; Lungs, Kidney, Adrenal, Thyroid, Uterus � Osteoblastic deposits – Prostate, Bladder, Testis, Breast and Bowel secondaries. Also carcinoid lung tumors, lymphoma � Mixed- Breast, Lung, Ovary, Cervix � Lymphoma deposits may resemble prostatic deposits, i. e. sclerotic secondaries � Lytic, expansile, with soft tissue mass- RCC, thyroid � X-Ray- at least 50% loss of bone to produce lysis on X-ray, Loss of single pedicle produces a “winking owl sign”. CT scan, MRI

Osteolytic bone metastases: breast carcinoma shows multiple osteolytic bone lesions.

Osteoblastic bone metastases

Mixed pattern bone metastases:

Lymphoma � Early - vague mottled lucent areas � Diffuse destructive lytic lesion with little periosteal reaction � Usually combination of patchy sclerosis and mottled destruction � Hogkins disease - typical appearance of ivory vertebrae

Myeloma � May be generalised decrease in bone density � Multiple � Little punched out defects bony reaction around lesions � Solitary lesion = plasmacytoma; multilocular expanding lytic lesion in a red marrow area � Frequently cold on bone scan

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