description about bone forming tumors and fibrous dysplasia

1. BONE FORMING
TUMOURS &
FIBROUS
DYSPLASIA
Presented by: ARUN KUMAR
Moderator: Dr. SHIKHA PRAKASH

2. NORMAL BONE
Parts of bones
1. Epiphysis : ends of bone
2. Diaphysis : shaft
3. Metaphysis : epiphysial end of
diaphysis
Macroscopically the architecture of bone
may be
1. Compact
2. cancellous/spongy/trabeculae

3. NORMAL BONE
On longitudinal
section the bone is
composed of :
1. Periosteum
2. Cortex
3. endosteum
4. Medullary cavity

4.  Unmineralised matrix laid down by osteoblasts
 Stains homogenously pink on H&E
 On polarized light demonstrates criss cross or
woven pattern of collagen fibers
 Can be confused with fibrin, collagen or
chondroid.
OSTEOID

5. NORMAL BONE
Woven bone : In these, collagen is deposited in a
random weave manner.
Lamellar bone : Collagen is deposited in a order. It
replaces woven bone during growth ,deposited much
slowly & stronger than woven bone

6. Woven bone (top) deposited on the surface of
preexisting lamellar bone(bottom)

7. WHO CLASSIFICATION OF
BONE TUMOURS

8. Histologic Type Benign Malignant
Chondrogenic (22%) Osteochondroma Chondrosarcoma
Chondroma
Dedifferentiated
chondrosarcoma
Chondroblastoma
Mesenchymal
chondrosarcoma
Chondromyxoid
fibroma
clear cell
chondrosarcoma
Osteogenic (19%) Osteoid osteoma Osteosarcoma
Osteoblastoma
Fibrogenic
Desmoplastic
fibroma

9. notochordal tumors Chordoma
Histiocytic origin
Benign Fibrous
histiocytoma
Malignant fibrous
histiocytoma
Ewing’s
sarcoma/PNET
Giant cell tumor
Malignant Giant cell
tumor
Hematopoietic (40%) Myeloma
Malignant lymphoma
Joint lesions
Synovial
chondromatosis
Vascular Hemangioma
Hemangioendotheliom
a
Hemangiopericytoma,
angiosarcoma

10. Lipogenic Lipoma Liposarcoma
Neurogenic Neurilemmoma
Smooth muscle tumors Leiomyoma Leiomyosarcoma
Miscellaneous tumors Adamantinoma
Metastatic malignancy
Tumours of
unidentified neoplastic
nature
Aneurysmal bone cyst
Simple cyst
Fibrous dysplasia
Langerhan’s cell
histiocytosis
Chest wall hamartoma
Osteofibrous dysplasia

11. BONE FORMING TUMOURS
1. OSTEOID OSTEOMA
2. OSTEOBLASTOMA
3. OSTEOSARCOMA
 CONVENTIONAL OS
 TELANGIECTATIC OS
 SMALL CELL OS
 LOW GRADE CENTRAL OS
 SECONDARY OS
 PAROSTEAL OS
 PERIOSTEAL OS
 HIGH GRADE SURFACE OS

12. OSTEOID
OSTEOMA

13. OSTEOID OSTEOMA
 Benign lesion characterized by less than 2 cm pea like
mass of abnormal bone-nidus
 Limited growth potential
 Clinical features
1. children & adolescents, occasionally in older individuals
2. more common in males
3. any bone except sternum.
1. most common in the long bones (metaphysis or shaft).
2. The tumour tend to involve the cortex rather than medulla

14. OSTEOID OSTEOMA
 Signs & symptoms:
1. Pain-characteristically relieved by salicylates and
NSAIDS
2. Swelling & redness
3. Joint effusion
4. Scoliosis
5. Bone growth abnormalities
 Genetics : involvement of 22q13 & loss of 17q

15. OSTEOID OSTEOMA:
RADIOLOGIC FINDINGS
 X-RAY : Dense
cortical sclerosis
surrounding a
radiolucent nidus,
 CT SCAN : best
imaging study to
demonstrate OO, help

16. OSTEOID OSTEOMA:
RADIOLOGIC FINDINGS
 MRI SCAN: Useful in demonstrating medullary
or periarticular lesions and peri-tumoural oedema,
also help to localize the lesion
BONE SCAN: associated with hot bone scan,
helpful in localizing the lesion

17. OSTEOID OSTEOMA : GROSS
FINDINGS
Small , cortically
based, red, gritty
or granular round
lesion
surrounded (well
circumscribed)
by ivory white
sclerotic bone

18. MICROSCOPIC FINDINGS
 The tumour consists of a central area of
vascularised connective tissue within which
differentiating osteoblasts are engaged in the
production of osteoid and sometime bone
 if actual bone is present osteoclast may also
be seen engaged in remodelling

19. OSTEOID OSTEOMA
Low power
view
showing
wedge
shaped
nidus
protruding
slightly
above the
surface and
surrounded
by sclerotic
bone
Central nidus with
dense sclerotic
bone

20. Osteoid osteoma shows anastomosing irregular
bony trabeculae with osteoblastic rimming
embedded in a hypocellular fibrovascular stroma

21. PROGNOSIS
 Prognosis is excellent
 Recurrence is rare

22. DIFFERENTIAL DIAGNOSIS
 SOLITARY ENOSTOSIS
 OSTEOMYELITIS
 BRODIE’S ABSCESS
 OSTEOBLASTOMA
 OSTEOSARCOMA

23. Osteoid osteoma v/s Solitary
enostosis
SOLITARY
ENOSTOSIS : does
not cause pain or
host bone sclerosis.
Usually consists of
lamellar bone with
haversian systems

24. Osteoid osteoma v/s
Osteomyelitis
Chr osteomyelitis : showing necrotic bone,chr
inflammation & fibrosis

25. Osteoid osteoma v/s Brodie’s
abscess
Image shows fibrosis , degenerating bony spicules, &
subacute inflammation

26. OSTEOBLASTOMA

27. OSTEOBLASTOMA
 A rare benign tumor, usually larger than 2 cm,
characterized by osteoid and woven bone
production.
 Age: 10-30 yrs
 M:F is 2.5:1
 Skeletal distribution: predilection for spine
particularly posterior elements and sacrum, others-
long bones-proximal and distal femur, proximal
tibia
 Site: majority intra-osseus but a small percentage
can occur on the surface of the bone in a

28. OSTEOBLASTOMA
Symptoms: dull, aching, nocturnal pain not relieved
by aspirin
Genetics : 1. chromosomal rearrangements have
been described in 4 cases, with chr no. ranging
from hypodiploid to hyperdiploid.
2. MDM2 amplification
3. TP53 deletion in aggressive
osteoblastoma

29. OSTEOBLASTOMA:
RADILOGICAL FINDINGS
 SPINAL LESION
1. Main mass centered in
vertebral arch
2. Round to ovoid lytic lesion
with bone expansion
3. Periosteal new bone
formation
4. Intra-lesional bone forming

30. X-ray showing expansion of the left fourth lumbar pedicle :
transeverse process and superior facet

31. OSTEOBLASTOMA: GROSS
FINDINGS
 Lesion is well
demarcated,
 Round to oval with thin
cortex
 Mostly granular, gritty, &
deep red on cutting
 Whitish yellow if bone

32. Osteoblastoma: excised specimen of femoral lesion
showing a well demarcated fleshy tumour

33. OSTEOBLASTOMA:
MICROSCOPIC FINDINGS
 Tumour is composed of woven bone spicules
or trabeculae which are arranged haphazardly
& lined by single layer of osteoblast
 Rich vascularity
 Osteoblast may have mitosis but not atypical
 Scattered multinucleated giant cells often
present

34. OSTEOBLASTOMA:
MICROSCOPIC FINDINGS
 Tumour has a pushing border
 Secondary ABC like changes may be seen
 Some osteoblastomas show multiple small
nidi

35. Osteoblastoma shows trabeculae of woven bone
lined by layer of polygonal osteoblast and the well
vascularised inter-trabecular stroma

36. OSTEOBLASTOMA:
MICROSCOPIC FINDINGS
Malignant osteoblastoma : histologically same but are
more cellular, has large no. of giant cells & large amount
of spiculated blue bone.
locally aggressive & does not develop distant
metastasis
Aggressive osteoblastoma : characterised by presence
of epitheloid osteoblasts, trabecular or sheet-like osteoid &
osteosclerotic resorption. locally aggressive & does not
develop distant metastasis
Pseudomalignant osetoblastoma : tumor cells have
hyperchromatic nuclei. However, the nuclei have the

37. Osteoblastoma : prominent epithiloid appearance

38. OSTEOBLASTOMA :
PROGNOSIS
Prognosis is excellent
Recurrence is unusual and may occur in a bone
which has difficult surgical access

39. OSTEOBLASTOMA:D/D
1.Osteoid osteoma
2.Osteosarcoma
3.Giant cell tumor
4.Aneurysmal bone cyst

40. 0steoid osteoma osteoblastoma
1. involvement Every bone except
sternum
Predilection for spine
2. size < 2cm > 2cm
3. pain Characteristically
relieved by NSAIDs
Not relieved by
NSAIDs
3. imaging Dense, cortical
sclerosis surrounding
a radiolucent nidus
Lytic, well
circumscribed ,
confined by a
periosteal shell of
reactive bone
4. gross Gritty or granular
round lesion
surrounded by ivory
white sclerotic bone
Round to oval, thinned
cortex & periosteal
reactive bone
5. microscopy Central nidus with
dense sclerotic bone
Composed of woven
bone trabeculae
arranged haphazardly

41. Osteoblastoma v/s GCT
GIANT CELL
TUMOR: located
in epiphysis,
packed with giant
cells and stromal
cells

42. OSTEOBLASTOMA: D/D
ABC Osteoblastoma
1. Age First 2 decade 10-30yr
2. Sex No sex predilection M>F
3. Site Metaphysial Majority intraosseus
4. Gross Well demarcated,
multiloculated mass of
blood filled cystic
spaces separated by
tan white gritty septa
Well demarcated,
round to oval.
Granular, gritty & deep
red on cutting
5. Microscopy
6. Recurrence
Well circumscribed,
blood filled cystic
spaces, separated by
fibrous septa rich in
collagen producing
fibroblasts & callus like
tissue
Tumor composed of
haphazardly arranged
woven bone spicules
or trabeculae
Unusual

43. Osteoblastoma v/s ABC
ABC with blood filled cystic space surrounded by wall containing
proliferating fibroblasts, reactive woven bone, & osteoclast type
giant cells

44. OSTEOSARCOMA

45. OSTEOSARCOMAS
 Osteosarcomas is a mesenchymally derived malignant
tumor that produces osteoid and/or bone.
 They can be:
1. INTRAMEDULLARY OS
2. INTRACORTICAL OS
3. JUXTACORTICAL OS

46. OSTEOSARCOMA
 PRIMARY OSTEOSARCOMA
1. CONVENTIONAL OSTEOSARCOMA
a) Osteobalstic
b) Chondroblastic
c) Fibroblastic
2. SMALL CELL OSTEOSARCOMA
3. TELANGIECTATIC OSTEOSARCOMA
4. LOW GRADE CENTRAL OSTEOSARCOMA

47. OSTEOSARCOMA
5. SURFACE OSTEOSARCOMA
a) Parosteal osteosarcoma
b) Periosteal osteosarcoma
c) High grade surface osteosarcoma
 SECONDARY OSTEOSARCOMA
1. Osteosarcoma in paget’s disease
2. Postirradiation osteosarcoma
3. Osteosarcoma in other benign precursors

48. age/sex site c/f prognosis
Convention
al OS
2nd decade
M>F
Metaphysis
(91%) of
long bones
Pain,swellin
g,path #
If untreated
fatal
Telangiectat
ic OS
(<4%)
2nd decade
M>F
Metaphysis
of long
bones
Pain,swellin
g ,path #
As above
Small cell
OS(1.5%)
2nd decade,
slightly mc
in female
>50%
metaphysis
of long
bones
Pain,swellin
g
Slightly
worse than
convention
al OS
Low grade
central
OS(1-2%)
2nd-3rd ,
M=F
80% in long
bones
Pain,swellin
g
excellent

49. age/sex site c/f prognosis
OS sec. to
paget ds
65yr
M>F,2:1
Long
bones,
pelvis, skull
Pain,
swelling,
path#
Poor
Post-
radiation
OS (3.4%-
5%)
Children
are at
greatest
risk
Any bone,
mc in pelvis
& shoulder
region
Pain,
swelling
5yr survival
rate for
extremity
lesion is
68.2% &
axial lesion
27.3%
Parosteal
OS
Young
adult, slight
female
predominan
ce
Long bones Pain,
swelling,
inability to
flex the
knee
excellent

50. age/sex site c/f prognosis
Periosteal
OS
2nd-3rd
decade
Slightly mc
in male
Diaphysial
or dia-meta
region of
long bones
Painless
swelling
initially,
later pain
excellent
High grade
surface OS
2nd decade,
slightly mc
in male
Long bones Mass &/or
pain
Depend
upon
response to
chemothera
py

51. CONVENTIONAL OSTEOSARCOMA

52. CONVENTIONAL
OS:RADIOLOGIC FINDINGS
 Metaphysial location
 It may be pure oseoblastic or
osteolytic. In most cases it is mixed
lytic/blastic lesion accompanied by
cortical destruction and extension
into soft tissue
 Tumours tend to be eccentric.
Mixed blastic/lytic lesion
involving the femoral metaphys

53. CONVENTIONAL
OS:RADIOLOGIC FINDINGS
 Periosteal reaction:
1. Codman’s triangle
2. Longitudinal laminations
3. Perpendicular spiculations
 Soft tissue mass

54. CONVENTIONAL OS :GROSS
FINDINGS
 OS often a large (over
5cm), metaphysial centered , fleshy
or hard tumour which may contain
cartilage
 It frequently transgresses the
cortex & is associated with a soft
tissue mass

55. CONVENTIONAL OS
:MICROSCOPIC FINDINGS
1. It is highly anaplastic , pleomorphic tumor.
2. The tumour cells may be epithelioid ,plasmacytoid ,
fusiform, ovoid, small round cells, clear cells, giant
cells or spindle cells. Most cases are mixture of 2 or
more of these cell types.
3. Osteoid and/or bone production by tumor cells.
dense, pink, amorphous,curvilinear with small
nubs,arborisation,abortive lacunae formation,
intercellular material.

56. On the basis of production of predominant matrix
by tumors the conventional OS is subdivided into:
1. OSTEOBLASTIC (50%)
2. CHONDROBLASTIC (25%)
3. FIBROGENIC (25%)

57. OSTEOBLASTIC
OSTEOSARCOMA
1. Bone &/or osteoid are
the predominant
matrix
2. The matrix may be
thin, arborising
osteoid (i.e.,
filigree) to dense
compact osteoid &
Osteoblastic OS: showing
osteoid

58. OSTEOBLASTIC
OSTEOSARCOMA
Filigree osteoid
comprises thin,
randomly arborizing
lines of osteoid
interweaving b/w
neoplastic cells
Flat and thick osteoid

59. CHONDROBLASTIC
OSTEOSARCOMA
 Chondroid matrix is predominant.
 It tends to be high grade hyaline cartilage.
 Myxoid and other forms of cartilage are
uncommon, except in the jaws & pelvis.
 Osteoid is seen between spindle cells or in center of
chondroid lobules.

60. CHONDROBLASTIC OSTEOSARCOMA
Lobules of malignant cartilage. There is spindling at the
periphery and osteoid formation.

61. FIBROBLASTIC
OSTEOSARCOMA
 25% of all conventional osteosarcoma
 A high grade spindle cell malignancy
 Minimal matrix production

62. Unusual forms of osteosarcoma
1.Epitheloid osteosarcoma
2.Ostoblastic osteosarcoma – sclerosing type
3.Osteosarcoma resembling osteoblastoma
4.Chondromyxoid fibroma-like osteosarcoma
5.Chondroblastoma-like osteosarcoma
6.Clear cell osteosarcoma
7.Malignant fibrous histiocytoma-like osteosarcoma
8.Giant cell rich osteosarcoma
Not associated with specific biologic behaviour that
differs from conventional osteosarcoma.

63. TELANGIECTATIC
OSTEOSARCOMA

64. TELANGIECTATIC
OSTEOSARCOMA
Lytic lesion , poorly
marginated,
Cortical bone
destruction without
distinct surrounding
bony sclerosis
Periosteal reaction
frequent

65. TELANGIECTATIC OSTEOSARCOMA
Tumor has hemorrhagic red-brown appearance
resembling blood clot

66. TELANGIECTATIC
OSTEOSARCOMA
Resmbles aneurysmal
bone cyst at low power
TELANGIECTATIC
OSTEOSARCOMA
Shows malignant osteoid

67. TELANGIECTATIC OSTEOSARCOMA
Hypercellular pleomorphic stromal cells within solid septa
adjacent to cystic space. Mitosis seen

68. SMALL CELL OSTEOSARCOMA

69. Small cell OS of distal
femur : X-ray image
showing lytic and
blastic tumour tissue
at the soft tissue
compartment of the
lesion.
SMALL CELL
OSTEOSARCOMA

70. SMALL CELL
OSTEOSARCOMA
GROSS : Indistinguishable from those of conventional
OS
HISTOPATHOLOGY
•Small cells associated with osteoid production.
•Tumours are classified according to predominant cell
type : round cell type or spindle cell type.
•The nuclear diameter of round cells can be very
small(comparable to Ewing sarcoma) to
large(comparable to large cell lymphoma).

71. Small cell osteosarcoma, small cell type. Osteoid
production at lower right.

72. CENTRAL LOW GRADE
OSTEOSARCOMA

73. CENTRAL LOW
GRADE
OSTEOSARCOM
A
Cut surface shows a grey
white tumour with a firm
& gritty texture arising
from the medullary cavity.

74. CENTRAL LOW GRADE
OSTEOSARCOMA
Microscopy
 Tumor is composed of hypocellular spindle
cell proliferation.
 The osteogenic matrix is produced as well
formed trabeculae of bone.
 The spindle cell show minimal cytolgical
atypia
 Mitotic figures are sparse.
 The tumor tend to permeate marrow fat &
surrounding bony trabeculae.

75. CENTAL LOW GRADE OSTEOSARCOMA
Bony trabeculae surrounded by a hypocellular
spindle cell stroma with minimal cytologic atypia.

76. OS SECONDARY TO
PAGET'S DISEASE

77. OS SECONDARY TO PAGET'S
DISEASE
Grossly : destructive tumors along with fleshy soft
tumors
 Microscopically: high grade OS, mostly osteoblastic or
fibroblastic. A great number of osteclast like giant cell
may be found.
Genetics : linked to 18q

78. PAGET’S SARCOMA
Proximal femur shows
thickened cortical and
medullary bone
characteristic of underlying
paget’s disease with a large
hemorrhagic tan-white
sarcomatous tumor that has
broken through cortex

79. PAGET’S SARCOMA
High grade osteosarcoma permeating abnormal bone
seen in Paget’s disease which is thickened and lined by
osteoclasts

80. POST-IRRADIATION
SARCOMA

81. POSTIRRADIATION
SARCOMA
Criteria for diagnosis
1. The affected bone may have been normal/benign
tumour/non-bone forming malignancy.
2. History of prior radiation therapy & tumour
developed in the path of radiation beam.
3. A symptom free latent period must follow.
4. Sarcoma must be biopsy proven.

82. DIFFERENTIAL DIAGNOSIS
OF OS
 CALLUS
 OSTEOBLASTOMA
 ANEURYSMAL BONE CYST
 CHONDROBLASTOMA
 GCT
 EWING’S SARCOMA
 MALIGNANT LYMPHOMA
 CHONDROSARCOMA
 FIBROSARCOMA
 FIBROUS DYSPLASIA

83. HISTOLOGIC
FEATURES
CALLUS OSTEOBLASTOM
A
OSTEOSARCOM
A
Osteoblastic
rimming
+++ 0-++ 0
Trapping of host
lamellar bone
0-++ 0 ++-+++
Circumscribed 0 +++ 0
Lesional fibrous
tissue
0-+++ No ++-+++
Lesional hyaline
cartilage
0-+++ Very rare 0-++++
Scattered atypical
nuclei
0 Rare 0-++++
Atypical mitotic
figures
0 0 0-++++
Extensive necrosis 0-+ 0 0-+++

84. Osteosarcoma v/s callus

85. HISTOLOGIC FEATURES ANEURYSMAL BONE
CYST
TELANGIECTATIC
OSEOSARCOMA
Osteoblastic rimming 0-++ 0
Trapping host lamellar bone - 0-++++
Pure woven bone Yes or no Yes
Lesional fibrous tissue 0-+ 0-++
Scattered atypical nuclei Rare +-+++
Atypical mitotic figures 0 0-+++
Large blood filled cysts +-++++ +++
Extensive necrosis 0-+ +-++++
Anaplasia - Yes

86. Osteosarcoma v/s ABC
ABC with blood filled cystic space surrounded by wall containing
proliferating fibroblasts, reactive woven bone, & osteoclast type
giant cells

87. HISTOLOGIC FEATURES FIBROUS DYSPLASIA LOW GRADE OS
Osteoblastic rimming 0 0-+
Trapping host lamellar
bone
0 0-++
Pure woven bone Yes Usually no
C &Y spicules of bone Yes No
Lesional fibrous tissue ++-+++ +-++
Lesional hyaline cartilage Rare 0-++
Scattered atypical nuclei Rare +-++
Atypical mitosis 0 0-+
Extensive necrosis 0 0-+

88. DIFFERENTIAL DIAGNOSIS
OF OS
Chondroblastoma : Epiphyseal centering , it is rarely
occur in OS
Fibrosarcoma : Not associated with any tumor osteoid,
bone, or cartilage
Chondrosarcoma : >50yr, cartilage forming tumor, on X-
ray it present as area of radiolucency with variably
distributed punctate opacities, periosteal reaction is
absent or minimal, osteoid is absent

89. Osteosarcoma v/s GCT
Giant cell tumor : epiphysial
centering, occur in 20-40yr, show
bone expanding & eccenteric area of
lysis, & multinucleated giant cells on

90. Features distinguishing both are:
1. Location
2. Codman’s triangle
3. Intralesional bone fluffs
4. Anaplasia of stromal cells
5. Production of malignant osteoid
OSTEOSARCOMA vs GCT

91. OS v/s Ewing sarcoma
Ewing sarcoma : More common in men,
pelvis & ribs are mc site, onion skin
periosteal reaction seen on X-ray & on
histo composed of small round cells with

92. Osteosarcoma v/s
Chondroblastoma
Image showing
eosinophilic
chondroid matrix
with calcific
deposit.The
mononuclear cells
contain round to
oval nuclei
sorrounded by
pink cytoplasm.
Hyaline cartilage &
atypical mitosis

93. Osteosarcoma v/s
Chondrosarcoma
Chondrosarcoma
permeates around
pre-existing
trabecular bone

94. OSTEOSARCOMAS OF
SURFACE BONES
 PAROSTEAL OSTEOSARCOMA
 PERIOSTEAL OSTEOSARCOMA
 HIGH GRADE SURFACE OSTEOSARCOMA

95. PAROSTEAL
OSTEOSARCOMA

96. PAROSTEAL
OSTEOSARCOMA
Radiologic findings:
heavily mineralised
mass attached to
cortex, with broad
base

97. PAROSTEAL
OSTEOSARCOMA
 Gross findings:
1. Hard lobulated mass
attached to cortex
2. Nodules of cartilage may
be present; occ cartilage
may be incomplete cap
like
3. Soft at periphery
4. Fleshy, soft areas

98. PAROSTEAL
OSTEOSARCOMA
 Microscopic findings:
1. Well formed bony trabeculae
2. Hypocellular stroma
3. With or without osteoblastic rimming
4. Stromal cells show minimal atypia
5. 20% show moderate atypia
6. 50% of the tumour show cartilage differentiation

99. Moderately atypical spindle tumor
cells grow between irregularly
shaped bone trabeculae
Shows mature appearing bone
surrounded by a hypocellular
fibroblastic stroma with minimal
cytologic atypia

100. DIFFERENTIAL DIAGNOSIS
 Fibrous dysplasia
 Myositis ossificans : It does not involve cortex, show
much more cellularity than parosteal OS & atypical
mitosis not seen
 Osteochondroma : In osteochondroma radiography
shows continuity between the bone and the
osteochondroma, and the intertrabecular spaces
contain fatty or hematopoietic marrow

101. Parosteal OS v/s Myositis
Ossificans
MO showing osteoid production in a cellular fibrous
tissue

102. Parosteal OS V/S
Osteochondroma
Image showing
thickened hyaline
cartilage cap
which mature via
enchondral
calcification to
bony trabeculae
surrounded by fat
& hematopoietic
marrow

103. PERIOSTEAL
OSTEOSARCOMA

104. PERIOSTEAL
OSTEOSARCOMA
 Radiologic findings:
1. Sunburst appearance
2. Codman’s triangle is frequent
3. Cortex appears thickened
4. CT-scan & MRI : important in the evaluation of
tumor size, integrity of cortex, soft tissue
extension, & relationship to soft tissue bundle

106. PERIOSTEAL
OSTEOSARCOMA
 Gross findings:
1. Tumor arises from bone surface
2. May involve part or entire circumference
3. Calcified spicules can be seen, longest in center
and tapering on both sides
4. Well delineated by capsule/pseudocapsule
5. Merges imperceptibly with cortex at base

108. PERIOSTEAL
OSTEOSARCOMA
 Microscopic findings:
1. Tumour is arranged in lobules with moderately
atypical chondrocytes
2. There is spindling at the periphery & spindle
cells shows matrix production
3. The centre of the chondroid lobule also show
bone formation

109. PERIOSTEAL OSTEOSARCOMA
Shows malignant chondroid matrix merging with
osteoid

110. HIGH GRADE SURFACE OSTEOSARCOMA

111. HIGH GRADE SURFACE
OSTEOSARCOMA
Radiologic findings: surface lesion , partially
mineralized, mass extending in soft tissue
Underlying cortex is destroyed with periosteal new
bone formation

112. HIGH GRADE SURFACE
OSTEOSARCOMA
 Gross findings:
1. Situated on surface of bone
2. Underlying cortex is eroded
3. Surface is multilobulated
4. Colour depends on amount of chondroid matrix,
hemorrhage & necrosis
5. Soft areas separate it from parosteal
osteosarcoma

113. HIGH GRADE SURFACE
OSTEOSARCOMA
 Microscopic findings: same features seen in
conventional OS
1. Show osteoblastic, fibroblastic or chondroblastic
differentiation
2. High grade cytologic atypia
3. Lace like osteoid
4. Chondroblastic area rich tumor may be confused
with periosteal osteosarcoma

114. HIGH GRADE SURFACE OS:
DIFFERENTIAL DIAGNOSIS
1. Parosteal OS :pattern of osteoid production & high grade
cytological atypia is seen in high grade OS
2. Periosteal OS : In high grade OS, tumour shows larger
regions of spindle cell morphology & more cellular atypia

115. Fibrous dysplasia

116. Fibrous dysplasia
• Benign medullary fibro-osseous lesion
• May involve one or more bone
• Occur in children & adults with equal sex distribution
• Sites : m.c. in jaw bones,in women long bones & in
men ribs & skull are favoured sites
• Types : 1. monostotic form(more common) : skull more
commonly followed by femur, tibia, ribs
2. polystotic form : femur, pelvis, tibia in majority
of cases

117. Fibrous dysplasia : Radiographic
features
-Often show a non-
aggressive lesion with a
ground glass matrix
-No soft tissue extension
-periosteal reaction is not
seen unless there is a
complicating fracture
-CT-scan & MRI better
define the extent
There is a well defined lucency with
Sclerotic margins

118. Fibrous dysplasia : Gross
features
The bone is often
expanded
 tan grey colour
firm-to-gritty
consistency.
There my be cysts,
which may contain some
yellow-
tinged fluid
circumscribed blue
tinged translucent
material if cartilage is

119. Fibrous dysplasia : Microscopy
 Well cirumscribed
 Composed of fibrous & osseus component
The fibrous component is composed of bland spindle
cell with low mitotic rate
The osseus component is comprised of irregular
curvilinear trabeculae of woven bone(rarely lamellar
bone)
Secondary changes : foam cells, multinucleated giant
cells, aneurysmal bone cyst or myxoid changes

120. Fibrous dysplasia : Microscopy
The fibrous stroma is composed of bland spindle cells
arranged in whorled or storiform pattern

121. Fibrous dysplasia : Microscopy
Anastomoting trabeculae of immature woven bone without
osteoblastic rimming

122. Fibrous dysplasia : Microscopy
Curvilinear trabeculae often describing as resembling
‘Chinese characters’

123. Fibrous dysplasia : Microscopy
Characteristic
C shaped
bony spicules
with spindle
cell stroma

124. Fibrous dysplasia : D/D
1. Parosteal OS :
• juxtacortical position,
• show moderate stromal anaplasia
2. Low grade intramedullary OS; fibrous dysplasia like :
•radiologically more aggresive, &
• lack rim of benign host bone sclerosis

125. Fibrous dysplasia : D/D
3. Osteofibrous dysplasia :
exclusively seen in tibia &/or fibula of
children < 10yr,
show predilection for cortex,
characteristically shows focal to diffuse
osteoblastic rimming of the bone trabeculae

126. Fibrous dysplasia
Genetics :1. Mutation in GNAS1 in monostotic & polystotic
forms
2. structural rearrangements involving 12p13 & trisomy
2
Prognosis : good , rarely malignant transformation may occu

127. SUMMARY
Constant
fundament
al tissue
Variable
fundament
al tissue
Reactive
tissue
(possible)
Benign to
locally
aggressive
tumor
Malignant
tumor
Osteoid,
&/woven
bone
A. Cartilage
B. No
cartilage
Fibrous,
OLGCs,
osteoclasts
osteoclasts
Callus(early
to
mid),periost
itis
ossificans
OO,OB
Osteosarco
ma all types
Osteoid ,
woven
bone, &
cartilage Osteoclasts
like giant
cells
Fibrous
dysplasia
Parosteal
OS

128. THANK YOU