Bone Tumor Pathology

Bone Tumor Pathology 

Carrie Y. Inwards, MD 

MMayo Cli Clinic i 

Rochester Rochester, MN

Bone Tumors 

• Benign Benign, malignant, malignant or non- 

neoplastic 

• Primary, secondary, or 

metastatic 

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Classification 

• Cl Classified ifi d according di tto cytology t l or 

products of the lesional cells 

• Chondroid or osteoid: Chondrosarcoma, 

osteosarcoma, etc 

• Fibrogenic: MFD, fibrosarcoma, etc 

• Notochord: Chordoma 

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Cartilage Tumors 

• Benign 

• Osteochondroma 

• Enchondroma 

• Ch Chondroblastoma 

d bl t 

• Chondromyxoid fibroma 

• Malignant 

• Chondrosarcoma

Osteochondroma 

• Benign outgrowth of cortical and 

medullary bone (“exostosis”) 

• 33% of benign bone tumors 

• 10% of all bone tumors 

• Majority ajo ty are a e solitary so ta y lesions es o s (spo (sporadic) ad c) 

• Multiple hereditary exostosis 

( (autosomal t l ddominant i t di disorder) 

d ) 

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• 60% of patients p proximal humerus > 

proximal i l tibi tibia 

• Solitary y lesions uncommon in small 

bones 

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Radiographic Features 

• Cortex and medullary cavity continuous 

with the underlying bone 

• Often arise at the site of tendon 

insertions ( (direction of f growth along line 

of tendon)


Gross Pathology 

• Sessile or pedunculated 

• Thin, regular, blue/grey cap (usually < 2 

cm) 

• Underlying cancellous bone 

• May be associated with a bursa 

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Histologic Findings 

• Cartilage cap 

• Chondrocytes in lacunae arranged in 

clusters peripherally and in columns 

near base of cap cap, simulating normal 

epiphyseal plate 

• Stalk 

• Cancellous bone surrounded by fat 

and dbbone 

marrow

Stalk 

Cartilage Cap 


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Chondrocytes arranged in 

columns at base of 

cartilage cap 

Osteochondroma


Differential Diagnosis 

• Parosteal osteosarcoma 

• Chondrosarcoma arising in 

osteochondroma 

• Bizzare parosteal osteochondromatous 

proliferation (Nora’s lesion) 

• HHeterotopic t t i ossification ifi ti 

• Subungual exostosis


Treatment 

• Surgical excision if lesion is 

symptomatic 

y p

Enchondroma 

• Benign, g , intramedullary, y, hyaline y cartilage g 

tumor 


• 60% of pts are between 15 and 40 yr of age 

• 50% located in the small bones (hands, feet) 

• MMost t commonly l a solitary lit ttumor 

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Multiple Enchondromas 

• Ollier disease 

• Multiple enchondromas involving the entire 

skeleton, half of the body, or one limb 

• Non-hereditary disorder 

• May show increased cellularity 

• Maffucci’s syndrome: 

• MMultiple lti l enchondromas h d with ith soft ft ti tissue 

hemangiomas 

Increased risk of de eloping 

• Increased risk of developing 

chondrosarcoma (~ 35%)

Enchondroma 


• Intramedullary area of rarifaction 

• Variable mineralization 

• Long bones: 

• Usually no cortical erosion or destruction 

• Small bones: 

• Cortex may be thinned and expanded

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Enchondroma 

Gross Features 

• Usually curetted lobulated fragments of 

grey/white g y tissue 

• No significant myxoid or mucoid quality

Enchondroma 

Histologic Features 

• Long and flat bones 

• Hypocellular; occasional moderately 

cellular areas 

• Bland cytologic y g features 

• Occasionally degenerative changes 

• Small bones 

• Moderately cellular, increase in nuclear 

size size, variable myxoid change 

• No invasion of medullary or cortical bone

Enchondroma abutting cortical bone – no evidence of invasion

Enchondroma – lobules of cartilage filling the marrow

Enchondroma in a long bone: hypocellular; no atypia

Enchondroma in a small bone: increased cellularity 

and nuclear enlargement

Enchondroma 


• Chondrosarcoma 

• Overall increased cellularity & 

cytologic atypia 

• Frequent permeation of cortical bone bone, 

entrapment of host bone 

• MMore aggressive i radiographic di hi 

features

• Curettage/grafting 

Enchondroma 

Treatment

Chondroblastoma 

• 1.4% of primary bone tumors 


• 60% involve long tubular bones 

• Di Distal t l ffemur > proximal i l hhumerus 

> 

proximal tibia 

• 60% in second decade of life



• Benign radiographic 

appearance 

• Lucent defect at the end 

of the bone 

• 40% confined to the 

epiphysis 

• 60% in epiphysis and 

metaphysis 

• 50% have a sclerotic rim



• Mononuclear cells with well-defined 

cytoplasmic y p boundaries, , oval-to 

elongated nucleus, eosinophilic 

cytoplasm y p 

• 95% contain cartilage matrix (usually 

pink) 

• 35% contain lace-like (“chicken wire”) 

calcification 

• Multinucleated giant cells common

Chondroblastoma: lobules of pink chondroid matrix 

surrounded by mononuclear cells

Chondroblastoma: cells with oval nuclei, eosinophilic cytoplasm, 

well defined cytoplasmic boundaries

Chondroblastoma: lobule of pink – blue chondroid matrix and 

multinucleated giant cells

Chondroblastoma with chunky (left) and “chicken wire” (right) 

calcification


• Differential Diagnosis 

• Giant cell tumor 

• Chondromyxoid fibroma 

• OOsteosarcoma t 

• Treatment 

• Curettage and bone graft

Chondromyxoid Fibroma 

• 0.5% of bone tumors 

• 11.6% 6% of benign bone tumors 

• Peak incidence in second and third 

decades 

• 45% occur in the long bones 

• Proximal tibia > distal femur 

• Flat bones: ilium and ribs 

• 30% in hands and feet



• Benign appearance 

• Usually y 

metaphyseal 

• Eccentrically located 

• Circumscribed 

• Scalloped p 

appearance with 

sclerotic rim



• Lobulated growth pattern 

• Macrolobules or microlobules 

• Cells with small oval to spindle 

shaped nuclei and pink cytoplasmic 

extensions 

• CCellular ll l proliferation lif ti of f oval l tto spindle i dl 

shaped cells and multinucleated giant 

cells ll surround d llobules b l

Chondromyxoid fibroma: macrolobular growth pattern

Chondromyxoid fibroma: Microlobular growth pattern

Chondromyxoid fibroma: microlobular growth pattern

Chondromyxoid fibroma: cells with small nuclei and cytoplasmic 

extensions


• Differential diagnosis 

• Chondroblastoma 

• Chondrosarcoma 

• TTreatment t t 

• Curettage

Chondrosarcoma 

• Conventional chondrosarcoma 

• Dedifferentiated chondrosarcoma 

• Clear Cell chondrosarcoma 

• MMesenchymal h l chondrosarcoma 

h d


• Males > females 

• 60% in 4th to 6th 60% in 4 to 6 decades of life 

• Two thirds located in pelvic and 

shoulder girdles and upper ends of the 

femur and humerus 

• < 3% distal di t l to t wrist i t and d ankle 

kl



• Usually large (ave. size 9.5 cm) 

• 75% are mineralized 

• Poorly marginated 

• 85% show h cortical ti l abnormalities 

b liti 

• Endosteal scalloping, cortical 

destruction, expansion of the bone 

• 40% with soft tissue mass

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Chondrosarcoma arising secondary in enchondroma (Ollier 

Disease)



• Lobulated, pale 

blue/white 

• Solid or partially cystic 

• Myxoid change 

common 

• Degenerative change 

and necrosis 

• Permeative

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• Hypercellular, nuclear enlargement and 

hyperchromasia 

• Permeation of cortical and medullary 

bone 

• Liquifactive myxoid change in matrix 

• Small bones: permeation required 

• Grades 1, 2, & 3

Chondrosarcoma: malignant cartilage permeating between host 

bone 

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Chondrosarcoma: hypercellular and nuclear atypia

Chondrosarcoma: permeative growth pattern

Chondrosarcoma: myxoid change in the matrix

Grade 1 Chondrosarcoma



Chondrosarcoma in a small bone permeating into 

soft tissue


Treatment 

• Surgery: wide resection 

• Not responsive to chemotherapy and 

radiation

Chondrosarcoma of Long Bones, 

Shoulder Girdle and Pelvis 

% with 

metastasis 

Survival Free of Metastasis 

100 

80 

60 

metastasis Grade Grade 2 + 3 

40 

20 

0 

Grade Grade 1 

0 2 4 6 8 10 12 14 16 18 20 

Years from Mayo diagnosis 

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Dedifferentiated 


• Occurs in 2 settings 

• De novo 

• In recurrent tumors 

• Old Older adults d lt ( (a ddecade d older ld th than 

conventional chondrosarcoma) 

• Pelvis and shoulder girdle most 

common sites

Dedifferentiated Chondrosarcoma 


• Oftentimes suggests 

dedifferentiation 

• Central portion has 

features of a 

cartilage til ttumor 

• Cortical and soft 

ti tissue portions ti 

usually look more 

aggressive

Dedifferentiated Chondrosarcoma


• Blue/grey cartilage 

tumor juxtaposed to 

a fleshy, tan/white 

sarcomatous tumor 

• VVariable i bl amounts t of f 

2 components 

• CCareful f l sampling! 

li ! 

Gross Features



• Bimorphic pattern 

• Low-grade Low grade chondrosarcoma 

juxtaposed to a high grade sarcoma 

• High grade sarcoma 

• Osteosarcoma, high grade spindle 

cell ll sarcoma, pleomorphic l hi 

undifferentiated sarcoma

Dedifferentiated Chondrosarcoma: low-grade malignant 

cartilage (left); high-grade osteosarcoma (right)

Dedifferentiated Chondrosacoma 

• Treatment 

• En bloc resection 

• +/- chemotherapy 

• PPrognosis i 

• Worse than conventional 

chondrosarcoma 

• 5 year y 

survival 10%

Clear Cell Chondrosarcoma 

• Extremely uncommon 

• Tends to involve the ends of the long 

bones (proximal femur and humerus) 

• Male predilection 

• 4th and 5th decades of life



• Lytic, extending to 

the end of the 

bone 

• Occasionally has 

a benign 

appearance 

•



• Lobulated growth pattern 

• Tumor cells have distinct cytoplasmic 

boundaries, central nucleus with 

prominent nucleolus, nucleolus clear cytoplasm 

• Trabeculae of woven bone commonly 

present 

• 50% of tumors contain nodules of 

conventional ti l chondrosarcoma 

h d

Clear cell chondrosarcoma: clear cells and hyaline cartilage

Clear cell chondrosarcoma: cells with clear cytoplasm and 


Clear cell chondrosarcoma

Clear Cell Chondrosacoma 


• Chondroblastoma 

• Osteoblastoma 

• Osteosarcoma

Mesenchymal Chondrosarcoma 

• 2/3 in bone; 1/3 in soft tissue 

• 50% in 2nd and 3rd 50% in 2 and 3 decades 

• Jaw bones common site 

• Ili Ilium, spine, i ribs 

ib

Mesenchymal Chondrosarcoma 

• Malignant radiographic appearance 

• Histologic features 

• Well differentiated hyaline cartilage 

merging or juxtaposed with highgrade 

small blue cell component

Malignant cartilage 

Small blue cells 

Mesenchymal Chondrosarcoma

Bone-Forming Tumors 

• Benign 

• Osteoid osteoma 

• Osteoblastoma 

• MMalignant li t 

• Osteosarcoma

Osteoid Osteoma 

• Size < 1.5 cm 

• Most common in adolescents and 

young adults 

• Three fourths of patients are between 

5 and 24 yrs 

• PPainful; i f l relieved li d with ith NSAID’s NSAID’ 

• Most common sites is the proximal 

femur


Radiographic Findings 

• Sclerosis and 

new bone 

surround the 

lesion 

• Small round nidus 

in cortex 

• CT helpful in 

identifying the 

nidus

• Well demarctated 

red/brown nidus 

• Surrounding 

sclerotic l ti or 

cortical bone 



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• Irregular trabeculae of woven bone 

surrounded by y loose fibrovascular 

stroma 

• Multinucleated giant cells common 

• Nidus sharply demarcated from 

surrounding bone

Nidus 

Osteoid osteoma: central nidus surrounded by trabeculae of bone

Osteoid osteoma: nidus with woven bone rimmed by osteoblasts


Treatment 

• Radiofrequency ablation 

• Surgical excision 

• Histologic confirmation of nidus

Osteoblastoma 

• Same histologic features as osteoid 

osteoma 

• > 2 cm 

• 75% of patients are under 25 yrs of age 

• Long bones > spine (body/dorsal 

elements) l t ) > jawbones 

j b

Osteoblastoma 


• Variable and nonspecific 

p 

• 25% simulate 

malignancy

• Tan/red-brown, 

friable 

• Well demarcated 

Osteoblastoma 

Gross Features

Osteoblastoma: trabeculae of woven bone surrounded 

by fibrovascular tissue

Osteoblastoma: woven bone, osteoblasts, fibrovascular stroma

Osteoblastoma: solid areas of bone production

Osteoblastoma 


• Osteosarcoma 

• Can be very difficult to make the 

distinction 

• Osteoid osteoma 

• ABC 

• Giant cell tumor

Osteosarcoma 

• Medullary 

• Conventional osteosarcoma 

• Surface 

• PParosteal t l osteosarcoma 

t 

• Periosteal osteosarcoma 

• High grade surface osteosarcoma

Osteosarcoma 

• Second most common malignant bone 

tumor 

• Mayo Clinic 

• 23% of primary bone tumors 

• 30% of primary p y malignant g 

tumors

Osteosarcoma 

• 85% before 30 years of age 

• Distal femur > proximal tibia > proximal 

humerus > proximal p femur 

• Metaphyseal region of the long bones

Osteosarcoma 


• Aggressive, 

destructive features 

• “Codman’s triangle” 

• Lytic Lytic, sclerotic 

• MRI and CT aid in 

evaluating l ti extent t t of f 

tumor

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Chondroblastic Osteosarcoma 

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Osteosarcoma 

Histologic Subtypes 

• Osteoblastic, chondroblastic, 

fibroblastic fibroblastic, telangiectatic telangiectatic, low low-grade grade 

central, giant cell rich, small cell 

• 85% % are high grade

Osteoblastic Osteosarcoma: permeating between host trabeculae

Osteoblastic Osteosarcoma: malignant osteoid in a lace-like 

pattern surrounding anaplastic tumor cells 

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Chondroblastic Osteosarcoma: malignant osteoid and cartilage

Fibroblastic Osteosarcoma: malignant spindle cell stroma 

and bone 

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Telangiectatic Osteosarcoma: fragments of cyst wall 

containing pleomorphic tumor cells 

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Osteosarcoma 

Treatment 

• Preoperative chemotherapy 

• Wide surgical resection 

• Postoperative chemotherapy

Fig 1. Event-free survival (EFS) and overall survival for 

patients newly diagnosed with osteosarcoma without 

clinically detectable metastatic disease 

Copyright Meyers, © American P. Society A. et of Clinical al. Oncology J Clin Oncol; 26:633-638 2008

OGS: Histologic % Necrosis s/p 

Neoadjuvant Chemotherapy 

• Important prognostic indicator 

• Huvos grading system 

• Grade 1: 90% necrosis: Good prognosis 

• < 90% necrosis: Poorer prognosis

Necrotic osteosarcoma following neoadjuvant chemotherapy

Low-Grade Osteosarcoma 

• Low-grade central (intramedullary) 

• Extremely rare 

• Radiographs show areas with 

aggressive features 

• Parosteal osteosarcoma

Parosteal Osteosarcoma 

• 4% of all osteosarcomas 

• Most common in young adults 

• Distal femur > proximal tibia > proximal 

humerus 

• posterior cortex of the distal femoral 

metaphysis t h i most t common site it 

• Treatment is wide resection without 

chemotherapy



• Heavily mineralized mass attached by a 

broad base to the underlying y g cortex 

• CT and MRI helpful in identifying 

whether there is medullary involvement



• Well formed trabeculae of bone 

• Spindle cells with minimal atypia 

• Cartilaginous differentiation in about half 

of tumors; occasionally in a “cap” cap 

• 15% contain a high-grade sarcoma 

(d (dedifferentiated diff ti t d parosteal t l 

osteosarcoma)

Parosteal osteosarcoma: long trabeculae of bone (left) 

surrounded by spindle cell stroma with minimal atypia

Periosteal Osteosarcoma 

• Chondroblastic, moderately 

differentiated osteosarcoma on the 

surface of bone 

• 11.5% 5% of osteosarcomas 

• Children and adolescents 

• Di Diaphysis h i of f ffemur and d tibi tibia

Periosteal Osteosarcoma: histologically chondroblastic 

osteosarcoma (right)

Fibrogenic Tumors 

• Fibrous dysplasia 

• Metaphyseal fibrous defect (non- (non 

ossifying fibroma)

Fibrous Dysplasia 

• Non-familial somatic mutation 

• Biology driven by activating oncogenic 

mutations of GNAS1 gene 

• Monostotic (80%) or polyostotic (20%)


• McCune Albright Syndrome 

• 3% of patients 

• Polyostotic fibrous dysplasia 

• Endocrine abnormalities 

• Cutaneous pigmentation 

• Mazabraud’s Mazabraud s syndrome 

• Very rare 

• Fib Fibrous ddysplasia l i 

• Soft tissue myxoma


• 75% diagnosed before 30 yrs of age 

• Femoral neck is the most common site 

• 1/3 in the craniofacial bones, 1/3 in the 

femur or tibia, and 20% in the ribs



• Well defined zone 

of rarefaction 

• Sclerotic rim 

• Mineralization: 

“ground glass” 

appearance

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• Irregular spicules of 

woven bone 

• Bland spindle cells 

• Occasionally foam 

cells, myxoid 

change change, fibrosis

Fibrous Dysplasia


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Treatment 

• Observation if asymptomatic 

• Curettage and grafting 

• Resection in some cases 

• LLocal l recurrence iis possible ibl 

• Polyostotic may be progressive

Metaphyseal Fibrous Defect 

• Also known as non-ossifying fibroma 

• Cortex or cortex and medullary cavity 

• 80% in the distal femur, distal tibia, and 

proximal tibia 

• Seen in as many as 35% of children



• Metaphyseal, 

eccentric 

• Sclerotic margin margin, 

circumscribed 

• Often diagnosed 

by x-ray alone

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• Plump spindle cells in a loose storiform 

pattern p 

• Multinucleated giant cells, foam cells, 

chronic inflammation 

• Mitotic activity

Metaphyseal fibrous defect: hypercellular fibrogenic stroma, 



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• Most are small and may regress 

spontaneously 

p y 

• Symptomatic, large, or atypical lesions 

are biopsied and treated surgically

Ewing Sarcoma 

• Fourth most common primary tumor of 

bone 

• Male predilection 

• 75% in the first 2 decades of life 

• 60% in pelvic girdle and lower 

extremities t iti 

• Femur > ilium > fibula

Ewing Sarcoma 


• Permeative, 

destructive, poorly 

defined margins 

• Periosteal new bone 

fformation ti “onion “ i 

skin” appearance 

• Di Diaphysis h i & 

metaphysis

Ewing Sarcoma 


• Small, round cell malignancy 

• Sheet-like Sheet like growth pattern in bone 

marrow; lobular or fillagree in soft tissue 

• Oval or round nuclei surrounded by 

clear or indistinct eosinophilic cytoplasm

Ewing Sarcoma 


• Classic / conventional / typical: ~ 70% 

• Pi Primitive iti neuroectodermal t d lttumor 

(PNET): ~ 15% 

• Atypical: ~ 15 – 20%

Ewing Sarcoma 


• Morphologic variation 

• Identical immunohistochemical and 

genetic features

Conventional Ewing Sarcoma: small blue cells with scant cytoplasm

Atypical Ewing Sarcoma: more cytologic variability

PNET: rosette formation

Ewing Sarcoma 

Immunohistochemistry 

• CD99 is the most helpful marker 

• SSensitive; iti not t 100% specific ifi 

• CD99: 95% 

• Keratin: 32% 

• FLI-1: FLI 1: 94%

Ewing Sarcoma 

Genetics 

• Most common translocation and fusion 

genes g 

• t(11;22)(q24;q12) EWSR1-FLI1 (95%) 

• t(21;22)(q22;q12) EWSR1 EWSR1-ERG ERG (5%) 

• Others (

Ewing Sarcoma 


• Primary consideration is lymphoma 

• Panel of immunostains is essential 

• T and B- cell markers: lymphoma 

• CD99 positive: iti EEwing i sarcoma and d 

lymphoblastic lymphoma

• Treatment 

Ewing Sarcoma 

• Neo-adjuvant chemotherapy 

• Wide resection 

• Adjuvant j chemotherapy py 

• +/- radiation 

• Histologic response to neo neo-adjuvant adjuvant 

chemotherapy 

• IImportant t t predictor di t of f survival 

i l

Ewing Sarcoma 

Prognosis 

• Grier et al NEJM; Feb 2003 

• 5 year event free survival: 70% 

• Overall survival: 72% 

• Child Children’s ’ oncology l group (COG): (COG) 

every-two week vs every-3-week 

chemotherapy h th cycles l show h an iimproved d 

(90%) overall survival

Ewing Sarcoma 

• Poor prognostic factors 

• Older age (>17 yrs) 

• Pelvic tumor 

• LLarge t tumor ( (>8 8 cm) ) 

• Metastatic disease

Giant Cell Tumor 

• BBenign, i llocally ll aggressive i 


• Majority are solitary; may be multiple 

• Most common in 3 to 5th decades 

• Female predilection


• Most common in the end (epiphysis) of 

the long g bones 

• Distal femur > proximal tibia > distal 

radius > sacrum 

• Anterior elements more common when 

located in the mobile spine



• Eccentric, purely lytic, 

end of bone 

• Cortical destruction, 

soft tissue mass with 

shell of bone 

• One fourth look 

aggressive

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• Numerous multinucleated giant cells 

scattered throughout g the tumor 

• Mononuclear cells with round to oval 

nuclei and eosinophilic cytoplasm 

• Mitotic activity 

• FFoam cells, ll reactive ti new bbone, 

occasional spindle cell areas, 

secondary d ABC

Giant Cell Tumor: numerous multinucleated giant cells

Giant cell tumor: stromal cells resemble cells in multinucleated 

giant cells

Giant cell tumor 

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Giant cell tumor: spindle-shaped and oval-shaped stromal cells


necrosis


Treatment 

• Curettage if the joint surfaces can be 

saved 

• Resection/reconstruction if joint 

surfaces can not be saved 

• Occasionally chemical cautery or 

cryosurgery

Aneurysmal Bone Cyst 

• May arise primary or secondarily in 

other tumors (most ( commonly y benign g 

tumors) 

• Most common in first and second 

decades of life; 50% in second decade 

• Most common sites are distal femur and 

proximal tibia; usually in the metaphysis 

• IIn the th spine, i the th posterior t i elements l t are 

most commonly affected



• Lucency in the 

metaphysis of long 

bones 

• May be eccentric, 

central, t l cortical, ti l or 

surface of bone 

• CCortex t may be b 

destroyed 

• Fluid Fluid-fluid fluid levels 

common

• Red-brown 


• Solid or cystic 

Gross Features



• Multiple cystic spaces separated by 

septa; p ; occasionally y “solid” 

• Fibrous septa composed of spindle cells 

without atypia, atypia mitotic activity activity, 

multinucleated giant cells; no 

endothelial lining 

• Osteoid and bony matrix (woven bone) 

may be present 

• Calcification frequently seen

ABC with cystic spaces surrounded by cellular septa

ABC: loose fibroblastic stroma of cyst wall, no cytologic 

atypia, multinucleated giant cells

Solid area of ABC with reactive bone and fibrous stroma

Anerurysmal Bone Cyst 

• Differential Diagnosis 

• Telangiectatic osteosarcoma 

• Giant cell tumor 

• TTreatment t t 

• Curettage 

• Occasionally resection for large 

lesions

Unicameral Bone Cyst 

• Also known as simple cyst 

• Majority of patients are in the first two 

decades of life 

• Pathologic fractures common 

• Proximal humerus and proximal femur 

are most t common sites 

it



• Located centrally in 

the medullary cavity 

abutting the 


• NNo wider id th than 


• Thi Thinned, d bbut t iintact t t 

cortex 

• Trabeculation



• Cyst wall fragments with bland spindle 

cells admixed with fragments g of bone 

• Irregular masses of degenerating fibrin 

that occasionally become calcified

UBC: fragments of bland cyst wall and bone

UBC containing eosinophilic fibrin


Treatment 

• Most are aspirated and injected with 

methylprednisolone 

yp 

• Occasionally curetted

Chordoma 

• Malignant tumor arising from notochord 

remnants 

• 6 % of malignant bone tumors 

• Males > females (2:1) 

• Most patients in the 5th to 7th decades 

• Patients with base of skull lesions 

generally a decade younger

Chordoma 

• Anatomic location 

• Sacrum: 50% 

• Base of skull: 37% 

• MMobile bil spine: i 13%

Chordoma 


• Often difficult to see in plain radiographs 

• CT & MRI most helpful in delineating 

the tumor 

• Lytic Lytic, destructive destructive, frequent soft tissue 

mass

• Lobulated 

• Gray-tan Gray tan, red- red 

brown, glistening, 

translucent 

Chordoma 

Gross Findings

Chordoma 


• Lobules separated by fibrous septa 

• Cords and nests of tumors cells in a 

pale blue myxoid background 

• Round nuclei with central nucleoli 

• Eosinophilic or clear cytoplasm with 

prominent i t iintracytoplasmic t t l i 

vacuolization (physaliphorous cell) 

• Chondroid chordoma

Chordoma 

Immunohistochemical Stains 

• Keratin positive 

• EMA positive iti 

• Brachyury positive

Chordoma: lobulated growth pattern

Chordoma: cells with round nuclei & vacuolated cytoplasm 

arranged in cords

Metastatic Bone Tumors 

• More common than primary bone 

tumors; ; carcinoma most common type yp 

• Adults: 80% are from lung, kidney, 

breast breast, prostate 

• Children: neuroblastoma, Wilm’s, OGS, 

Ewing’s Ewing s, rhabdomyosarcoma 

• Spine, pelvis, ribs, skull, proximal long 

bones

Metastatic Bone Tumors 


• Lytic: kidney, GI, 

thyroid, y , 

melanoma 

• Blastic: prostate 

• Both: breast, lung

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Metastatic adenocarcinoma Metastatic squamous cell CP1059536-110 ca

Metastatic Breast Carcinoma 

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Metastatic Renal Cell Carcinoma 

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Conclusion 

• Care of the patient requires a 

multidisciplinary approach 

• Pathologist 

• RRadiologist di l i t 

• Orthopedic surgeon 

• Medical oncologist 

• Radiation oncologist

Question #1

Question #1 

• The most likely anatomic site for this tumor 

would be: 

• Sacrum 

• Epiphysis of the femur 

• Metaphysis of the femur 

• Posterior vertebrae 

• Ilium

Question #2

Question #2 

• All but one of the following are false 

about this tumor except: p 

• It is most commonly seen in young 

adults 

• It is responsive to chemotherapy 

• It commonly l involves i l th the small ll bbones 

• It is graded on a scale of 1 to 3

Question #3

Question #3 

• The most effective treatment of this 

tumor is: 

• Surgery alone 

• Curettage 

• Surgery and chemotherapy 

• Radiation and surgery

Question #4

Question #4 

• This tumor: 

• Most commonly occurs in the 5th to 6th Most commonly occurs in the 5 to 6 

decades of life 

• Rarely occurs in the small bones 

• Contains a macro or micro lobular 

growth th pattern tt 

• Is the most common benign tumor in 

children

Question Q 

#5

Question #5 

• A tumor this these histologic features: 

• Would be consistent with a periosteal 

osteosarcoma 

• Would be consistent with a parosteal 

osteosarcoma 

• IIs most t commonly l seen in i th the pelvic l i 

bones 

• Frequently contains a secondary 

aneurysmal bone cyst component

Question #6

Question #6 

• A common finding in this tumor is: 

• EWSR1-FLI1 EWSR1 FLI1 fusion gene 

• SYT-SSX fusion gene 

• t(X t(X;18)(p11;q11) 

18)( 11 11) 

• t(11;12)(q22;21)

Question #7

Question #7 

• The radiographic and histologic findings 

given for this lesion: 

• Fit well 

• Do not fit well since the tumor is most 

likely located in the metaphysis 

• Do not fit well since the tumor is 

uncommon iin the h di distal l radius di 

• Do not fit well since the tumor is not 

destroying the cortex

Question #8

Question #8 

• This tumor 

• Has histologic features that overlap 

with chondroblastoma 

• Is often associated with pain that is 

relieved with steroids 

• IIs oftentimes ft ti effectively ff ti l treated t t d with ith 

observation only 

• Is frequently located in the proximal 

femur

Question #9

Question #9 

• This tumor: 

• Is rarely seen in the ribs 

• Results from GNAS1 mutation 

• Sh Shows radiographic di hi ffeatures t similar i il 

to ground stones 

• Most commonly located at the end of 

a long bone

Question #10

Question #10 

• This lesion 

• Is also known as non-ossifying non ossifying fibroma 

• Is effectively treated with chemotherapy 

and surgery 

• Contains few mitotic figures 

• Only rarely presents with a pathologic 

fracture

Question #11

Question #11 

• This tumor is frequently: 

• Located in the metaphysis of the long 

bones 

• Located in the sacrum 

• Affects children 

• Cytokeratin negative

Question #12

• This lesion 

Question Q #12 

• Radiographically shows cortical and 

medullary continuity between the 

lesion and underlying bone 

• Commonly involves the small bones 

• Commonly evolves into secondary 

chondrosarcoma 

h d 

• Contains fibrous tissue diffusely 

surrounding bone within the stalk

Question #13

Question #13 

• Common histologic findings of this 

lesion include all but one of the 

following: 

• Mitotic activity 

• Reactive or woven bone 

• CCalcification l ifi ti 

• Cytologic atypia 

• Solid and cystic areas

Question Q 

#14

Question #14 


• Frequently involves the small bones 

• Is commonly seen in children 

• Sh Shows radiographic di hi evidence id of f 

cortical thickening and scalloping 

• Commonly contains myxoid change 

within the matrix

Question #15


Question Q #15 

• Is associated with a relatively good 

prognosis 

• Contains low-grade chondrosarcoma & 

high g ggrade sarcoma components p 

• Contains high-grade chondrosacoma & 

high grade sarcoma components 

• Contains two histologic components 

that merge imperceptively with one 

another

Question #16

Question #16 


• Frequently involves the jaw bones 

• Frequently contains a high grade 

osteosarcoma component 

• Frequently contains a high grade 

cartilaginous til i component t 

• Is the most common malignant bone 

tumor of children

Bone Tumor Pathology

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