bone tumors

Question 1

Malignant mesenchymal tumor

forming bone

Answer 1

osteosarcoma

Question 2

Most common benign bone

tumor

Answer 2

osteochondroma

Question 3

Resembles growth plate
 Cartilage-capped outgrowths
(polypoid exostosis) at
epiphyseal growth plates

Answer 3

osteochondroma

Question 4

Can be differentiated from other
tumors with osteoclast-like giant
cells and ABC-like changes by:
o Mononuclear cells with
nuclear groove
o Chicken-wire calcifications
o Amphophilic to eosinophilic
fibrochondroid matrix

Answer 4

chondroblastoma

Question 5

Most common tumor of small
tubular bones (digits)

Answer 5

enchondroma

Question 6

enchondroma can be differentiaed from chondrosarcoma by

Answer 6

Lack of atypia
o Less cellular
o Absence of invasion of
marrow or soft tissue

Question 7

Most common nonhematopoietic
malignant bone
tumor in adults

Answer 7

chondrosarcoma

Question 8

Involve the axial skeleton
 Malignant mesenchymal tumor
forming cartilage
 Single best criterion for
diagnosis: permeation of bone marrow or invasion of soft tissues

Answer 8

chondrosarcoma

Question 9

Composed of spindle cells arranged
in storiform pattern with admixed
osteoclast-like giant cells

Answer 9

NON-OSSIFYING FIBROMA

Question 10

Similar to non-ossifying fibroma
(+) bony trabeculae not rimmed by
osteoblasts
 Chinese character shape of
trabeculae

Answer 10

fibrous dysplasia

Question 11

Similar to fibrous dysplasia except
that bony trabeculae are rimmed by
osteoblasts

Answer 11

ossifying fibroma

Question 12

Rare tumor
 Diagnosed only after careful search
for absence of osteoid
 Herringbone pattern

Answer 12

fibrosarcoma

Question 13

 May be clinically similar to
chronic osteomyelitis
 Aggressive small round cell
tumor of adolescents with
EWS gene rearrangements
 Most often assoc. with
t(11;22)
 Can be differentiated from
other small round blue cell
malignancy with the use of:
CD99 IHC or molecular
typing

Answer 13

ewing sarcoma/PNET

Question 14

 Usually located in
sacrococcygeal region
 Identified histologically by
the presence of
physaliferous cells

Answer 14

chordoma

Question 15

Composed of a mixture of
neoplastic mononuclear
cells and reactive
osteoclast-like giant cells

Answer 15

giant cell tumor

Question 16

Giant cell tumor can be differentiated from other giant cell rich tumors by

Answer 16

Nuclei of stromal cells
are similar with giant
cells
o Evenly distributed giant
cells with 20-50 nuclei

Question 17

 Hallmark: blood-filled cysts
lined by osteoclast-like giant
cells; rule out secondary
ABC

Answer 17

aneurysmal bone cyst

Question 18

Lined by thin fibrous tissue

with cementum-like material

Answer 18

unicameral or simple bone cyst

Question 19

Only metastatic tumor to the
bone that presents as
blastic lesion on xray

Answer 19

metastatic prostatic adenocarcinoma