Bone tumour by DR NIDHI

CHONDROBLAST
CHONDROCYTE
OSTEOBLAST &CYTES
OSTEOCLAST

WHO CLASSIFICATION OF BONE TUMOURS
CHONDROGENIC TUMOUR
BENIGN INTERMEDIATE(LOCALL
Y AGGRESSIVE)
INTERMEDIATE(RARE
LY
METASTATSIZING)
MALIGNANT
1. Osteochondroma
2. Chondroma
• Enchondroma
• Periosteal
Chondroma
3.
Osteochondromyxom
a
4. Subungual
exostosis
5. Bizarre parosteal
osteochondromatous
proliferation
6. Synovial
Condromatosis
1. Chondromyxoid
fibroma
2. Atypical
Cartilagenous
tumour/
Chondrosarcoma
grade I
1. Chondroblastom
a
1. Chondrosarcoma
Grade II , Grade III
2. Dedifferentiated
Chondrosarcoma
3. Mesenchymal
Chondrosarcoma
4. Clear cell
chondrosarcoma

OSTEOGENIC TUMOURS
BENIGN INTERMEDIATE MALIGNANT
1. Osteoma
2. Osteoid Osteoma
1. Osteoblastoma 1. Low Grade Central
Osteosarcomna
2. Conventional Osteosarcoma
• Chondroblastic OS
• Fibroblastic OS
• Osteoblastic OS
3. Telangiectatic OS
4. Small Cell OS
5. Secondary OS
6. Parosetal OS
7. Periosteal OS
8. High Grade Surface OS
OSTEOCLASTIC GIANT CELL RICH TUMOURS
1. Giant cell lesion of
the small bones
1. Giant cell tumour of
bone
1. Malignacy in giant cell tumour
of bone

FIBROGENIC TUMOURS
INTERMEDIATE (LOCALLY AGGRESSIVE) MALIGNANT
1. Desmoplastic Fibroma of bone 1. Fibrosarcoma of bone
FIBROHISTIOCYTIC TUMOURS
Benign Fibro histiocytoma/ Non ossifying Fibroma
HEMATOPOIETIC NEOPLASM
MALIGNANT
1. Plasma cell myeloma
2. Solitary Plasmacytoma of bone
3. Primary Non-Hodgkin lymphoma of bone
NOTOCHORDAL TUMOURS
BENIGN MALIGNANT
1. Benign Notochordal Tumour 1. Chordoma

VASCULAR TUMOUR
1. Hemangiom
a
1. Epithelioid Hemangioma 1. Epithelioid
hemangioepithelioma
2. Angiosarcoma
LIPOGENIC TUMOURS
BENIGN MALIGNANT
1. Lipoma of Bone 1. Liposarcoma of Bone
MYOGENIC TUMOURS
BENIGN MALIGNANT
1. Leiomyoma of Bone 1. Leiomyosarcoma of Bone

TUMOURS OF UNDEFINED NEOPLASTIC NATURE
BENIGN INTERMEDIATE(LOCALLY AGGRESSIVE)
1. Simple Bone Cyst
2. Fibrous dysplasia
3. Osteofibrous dysplasia
4. Chondromesenchymal Hamartoma
5. Rosai Dorfman Disease
1. Aneurysmal Bone Cyst
2. Langerhans cell Histiocytosis
• Monostotic
• Polystotic
3. Erdheim- Chester Disease
MISCELLANEOUS TUMOURS
1. Ewing Sarcoma
2. Adamantinoma
3. Undifferentiated high-grade pleomorphic Sarcoma of bone

OSTEOID OSTEOMA
• BENIGN BONE FORMING TUMORS , SMALL SIZED (<2 CMS) WITH LIMITED GROWTH
POTENTIAL
 AGE/SEX : CHILDREN & ADOLESCENT, 2ND DECADE, M>F (2:1)
 SITE: APPENDICULAR SKELETON – MOST COMMONLY PROXIMAL FEMUR
 CLINICAL FEATURES:
1. MILD PAIN WITH NOCTURNAL EXACERBATION.
2. PAIN IS COMPLETELY RELIEVED BY SALICYLATES AND NSAIDS. VERY LOCALIZED
TENDERNESS IS SEEN .
3. CAUSE OF PAIN HAS BEEN PROPOSED TO BE THE RELEASE OF PROSTAGLANDINS FROM
THE TUMOR( PROSTAGLANDIN E2)

RADIOGRAPHIC FINDINGS
• CHARACTERISTIC CORTICAL SCLEROSIS
SURROUNDING THE SMALL ROUND
CENTRAL RADIOLUCENT NIDUS.
• IN UNCOMMON CASES THE NIDUS MAY BE
OSSIFIED GIVING THE APPEARANCE OF A
TARGET.
• BEST IMAGING TECHNIQUE IS CT.

MACROSCOPIC FEATURES
• NIDUS-- SMALL ,INTRACORTICAL, RED
, GRITTY OR GRANULAR ROUND
LESION SURROUNDED BY IVORY WHITE
RIM OF SCLEROSIS.
• IT RARELY EXCEEDS 1.5 CM IN SIZE.

MICROSCOPIC FEATURES
• EXTREMELY WELL CIRCUMSCRIBED LESION
• CONSISTS OF A CENTRAL NIDUS SURROUNDED BY A ZONE OF SCLEROTIC BONE .
• CENTRAL NIDUS IS COMPOSED OF INTERLACING TRABECULAE OF WOVEN BONE OF VARIABLE
THICKNESS.
• TRABECULAE ARE RIMMED BY A LAYER OF OSTEOBLAST.
• INTERVENING HYPOCELLULAR FIBROVASCULAR STROMA.
• STROMA MAY SHOW MULTINUCLEATED OSTEOCLAST LIKE GIANT CELLS.
• NIDUS MAY SOMETIMES UNDERGO EXTENSIVE MINERALIZATION RESULTING IN CONFLUENT
AREAS OF OSTEOID AND BROAD BONY TRABECULAE. THE APPEARANCE MAY MIMIC PAGET'S
DISEASE OF BONE
FIG 2
Fig
1
Fig
3

DIFFERENTIAL DIAGNOSIS
1. OSTEOBLASTOMA (GIANT OSTEOID OSTEOMA)
OSTEOID OSTEOMA OSTEOBLASTOMA
1. Size <2 cm 1. Size > 2 cms
2. Site: appendicular m/c proximal
femur
2. Site: vertebral column & sacrum >
mandible>craniofacial bones >
extremities
3. Progressive nocturnal pain relieved by
nsaids
3. Painless or if painful it is dull, achy &
not responsive to salicylates
4. Typically intracortical 4. Intramedullary
5. Induce a reactive bone formation 5. The absence or inconspicuousness
reactive bone formation

D/D Mimicking Features Distinguishing Features from
osteoid osteoma
1. OSTEOMYELITI
S (BRODIES
ABSCESS)
Mimics it Radiologically and
Clinically
1. No central nidus
2. Prominent acute
inflammatory infiltrate
2. STRESS # Zonal Pattern with central, more
mature, denser bone and
peripheral woven bone
3.
OSTEOSARCOMA
Osteoid present Large Size, lack of well defined
margins and presence of
cytological atypia
IHC: STRONG NUCLEAR STAINING FOR REGULATORY TRANSCRIPTION FACTOR RUNX2 &
OSTERIX
PROGNOSIS: EXCELLENT WITH RARE RECURRENCES.

OSTEOBLASTOMA
• SITE:- PREDILECTION TO SPINE – POSTERIOR ELEMENT AND SACCRUM(40-55%).
ALSO INVOLVES THE JAW WHERE IT IS KNOWN AS CEMENTOBLASTOMA.
• THE HISTOPATHOLOGICAL APPEARANCE IS IDENTICAL TO THAT OF OSTEOID OSTEOMA.
• SOME OSTEOBLASTOMAS HAVE BIZARRE HYPERCHROMATIC NUCLEI, TERMED PSEUDO
MALIGNANT OSTEOBLASTOMAS
• MALIGNANT OSTEOBLASTOMA / AGGRESSIVE OSTEOBLASTOMA REFER TO A LESION THAT
RESEMBLES AN OSTEOBLASTOMA BUT IS LOCALLY AGGRESSIVE.
• D/D :-
OSTEOSARCOMA: DIFFERENTIATED BY PERMEATION
OSTEOID OSTEOMA:- DIFFERENTIATED BY THE SIZE
• PROGNOSIS:-
EXCELLENT WITH RARE RECURRENCES.

OSTEOSARCOMA
• PRIMARY INTRAMEDULLARY MALIGNANT NEOPLASM IN WHICH NEOPLASTIC CELLS PRODUCE
BONE.
• MOST COMMON PRIMARY MALIGNANT BONE TUMOUR, EXCLUSIVE OF HEMATOPOIETIC
MALIGNANCIES.
• AGE/SEX : BIMODAL AGE DISTRIBUTION
 75% IN 2ND DECADE
 REMAINING OCCUR IN OLD PT.(AFTER 40S) WITH UNDERLYING CONDITIONS
MALE TO FEMALE RATIO IS 1.6:1
• SITE:-
 LONG BONES OF APPENDICULAR SKELETON. LIKE DISTAL FEMUR ,PROXIMAL TIBIA, OR
HUMERUS.
 MOSTLY METAPHYSIAL (91%) MAY BE DIAPHYSIAL (9%).
• C/F:-
 NON SPECIFIC PAIN WITH OR WITHOUT A PALPABLE MASS.
 PATHOLOGICAL FRACTURE RARE AS INITIAL SYMPTOMS (10-15% CASES – IN

AETIOLOGY
1. PAGET DISEASE
2. RADIATION EXPOSURE
3. CHEMOTHERAPY: CHILDREN TREATED WITH ALKYLATING AGENTS FOR
RETINOBLASTOMA & OTHER MALIGNANCIES.
4. PREEXISTING BENIGN BONE LESIONS: FIBROUS DYSPLASIA, BONE INFARCT &
OSTEOGENESIS IMPERFECTA
5. FOREIGN BODIES: SITE OF TOTAL HIP REPLACEMENT OR ANY ORTHOPAEDIC IMPLANTS
6. GENETIC PREDISPOSITION:
 LI-FRAUMENI SYNDROME (TP53 MUTATION)
 HEREDITARY RETINOBLASTOMA (RB1 MUTATION)
 WERNER SYNDROME
 ROTHMUND-THOMSON SYNDROME
 FAMILIAL PAGET DISEASE

RADIOGRAPHIC FEATURES
• APPEARANCE IS VARIABLE,
• MAY BE OSTEOLYTIC OR OSTEOBLASTIC, BUT IN MAJORITY OF CASES THERE IS A MIXED PICTURE.
• LESION USUALLY APPEARS AS AREAS OF GEOGRAPHIC DESTRUCTION WITH EXTENSION INTO THE SOFT
TISSUE.
• TUMOUR BREAKTHROUGH THE COTEX AND LIFTS THE PERIOSTEUM RESULTING IN REACTIVE PERIOSTEAL
BONE FORMATION (PERIOSTEAL REACTION) – SUN BURST APPERANCE ON RADIOGRAPH
• THE TRIANGLE SHADOW BETWEEN THE CORTEC AND RAISED END OF THE PERIOSTEUM KNOWN
RADIOGRAPHICALLY AS CODMAN TRAIANGLE (INDICATIVE OF AGGRESSIVE OF TUMOUR) – CHARACTERISTIC
BUT NOT DIAGNOSTIC OF OSTEO SARCOMA.
• OSTEOID MATRIX PRODUCED BY THE TUMOR CELLS OFTEN CREATES A "FLUFFY" OR "CLOUD-LIKE"
APPEARANCE ON PLAIN FILMS
• CT & MRI- USED FOR STAGING ( INTRAMEDULLARY INVOLVEMENT K/A SKIP METASTASIS OR SATELLITE
NODULES , PRESENCE OF SKIP LESIONS IN MARROW AND SOFT TISSUE INVOLVEMENT)

• TYPICALLY ARISES IN THE METAPHYSIS &
SPREAD LONGITUDINALLY IN THE MEDULLARY
CAVITY.
• BREACHED THE CORTEX PRODUCING A SOFT
TISSUE MASS THAT COMPLETELY ENCIRCLED
THE BONE.
• C/S :
 VARIEGATED APPEARANCE
 SOFT, FLESHY AREAS, FOCI OF FIRM FIBROUS
TISSUE, AND GRITTY YELLOWISH TO WHITE
AREAS OF IRREGULAR OSSIFICATION
 AREAS OF NECROSIS AND HEMORRHAGE ARE
ALSO SEEN
 CHONDROBLASTIC AREA: LOBULATED,
TRANSLUCENT, AND LIGHT GREY TO WHITE

• CONVENTIONAL OS IS A SPINDLE CELL NEOPLASM OF HIGH GRADE THAT PRODUCES
OSTEOID MATRIX.
• HIGHLY ANAPLASTIC AND PLEOMORPHIC TUMOR WHERE THE NEOPLASTIC CELLS MAY BE
EPITHELIOID, PLASMACYTOID, FUSIFORM, OVOID, SMALL ROUND CELL , CLEAR CELL,
MONO OR MULTINUCLEATED GIANT CELL OR SPINDLE CELLS. MOST OF THE CASES ARE
COMPLEX MIXTURE OF TWO OR MORE OF THESE.
• TUMOUR CELLS ARE GROW IN DIFFUSE, NESTED OR PSEUDOPAPILLARY ARRANGEMENTS.
• ESSENTIAL TO THE DIAGNOSIS : IDENTIFICATION OF NEOPLASTIC WOVEN BONE.
• OSTEOID IS A DENSE , EOSINOPHILIC , AMORPHOUS INTERCELLULAR MATERIAL WHICH
MAY APPEAR REFRACTILE. .
• BRISK MITOTIC ACTIVITY WITH ATYPICAL FORMS

HISTOLOGICAL SUBTYPES
OSA CAN BE DIVIDED ON THE BASIS OF MATRIX THAT PREDOMINATES, INTO THREE TYPES
NAMELY
1. OSTEOBLASTIC (INCLUDING SCLEROSING)- 76-80%
2. CHONDROBLASTIC – 10-13%
3. FIBROBLASTIC-10%
OTHER HISTOLOGICAL SUBTYPES:
1. GIANT CELL RICH (NUMEROUS NON NEOPLASTIC OSTEOCLAST LIKE GIANT CELL
PRESENT)
2. OSTEOBLASTOMA LIKE ( NEOPLASTIC CELLS RIM THE NEOPLASTIC BONY TRABECULAE)
3. EPITHELIOID ( LARGE POLYHEDRAL TUMOUR CELLS PRESENT)
4. CLEAR CELL
5. CHONDROBLASTOMA LIKE

OSTEOBLASTIC OSTEOSARCOMA
• PRINCIPAL MATRIX- NEOPLASTIC BONE
• OSTEOID DEPOSITION IS EXTREMELY
VARIABLE RANGING FROM
 FINE, LACE LIKE TRABECULAE TO
 DENSE COMPACT BONE K/A
SCLEROSING TYPE.
• HEMANGIOPERICYTOMATOUS
VASCULAR PATTERN: UNMINERALIZED
OSTEOID MATRIX LINED BY
ANAPLASTIC TUMOR CELLS CAN BEE
SEEN IN SURROUNDING THE VASCULAR
CHANNELS.
HEMANGIOPERICYTOMATOUS VASCULAR
PATTERN
`SCLEROTIC
TYPE

CHONDROBLASTIC OSTEOSARCOMA
• PREDOMINANT MATRIX – NEOPLASTIC CARTILAGE WHICH IS HYALINE AND HIGH GRADE
• MYXOID CARTILAGE RARE – FOUND IN TUMOURS ARISING IN JAWS
• NEOPLASTIC CELLS-
 CHONDROCYTE PHENOTYPE
 PRESENT IN LACUNAE AND ARRANGED IN LOBULES
 THE PERIPHERY OF THE LOBULES IS HYPERCELLULAR AND SHOWS CONDENSATION
AND SPINDLING OF THE TUMOR CELLS
• OSTEOID PRODUCTION IS SEEN IN B/W SPINDLE CELLS OR IN THE CENTER OF LOBULE.

3
Hypercellular Peripheral area with
spindling
Hypocellular central area of the lobules
4
5 6

FIBROBLASTIC OSTEOSARCOMA
• HIGH GRADE SPINDLE CELL MALIGNANCY
WITH ONLY A MINIMAL AMOUNT OF
OSSEOUS MATRIX WITH OR WITHOUT
CARTILAGE IS THE HALLMARK.
• TUMOUR CELLS ARE ARRANGED IN
STORIFORM PATTERN AND MAY SHOW
MYOFIBROBLASTIC DIFFEREBTIATION-
HISTOLOGICAL FEATURES SIMILAR TO MFH
• PREVIOUSLY ALSO KNOWN AS MFH LIKE
VARIANT
1
2

IMMUNOHISTOCHEMISTRY
• LACK DIAGNOSTIC UTILITY, MAIN UTILITY IS TO EXCLUDE OTHER DIAGNOSTIC
POSSIBILITIES E.G METASTATIC CARCINOMA
IHC +/- SPECIFIC FINDING
1. ALKALINE PHOSPHATASE + Strong activity regardless of their
appearance (osteoblastic or
fibroblastic)
2. PROTEINS- OSTEOCALCIN &
OSTEONECTIN
+ Highlight Osteoid
3. CYTOKERATIN (CK) + Consistently positive
4. CD 99 + Diffuse cytoplasmic posItivity
5. SMOOTH MUSCLE ACTIN (SMA) AND
DESMIN
+ Cases with Myofibroblastic or Myoid
differentiation
6. SATB2 (RECENTLY DISCOVERED) + Osteoblastic Transcription Factor
Nuclear PosItivity
Critical for Osteoblast Lineage
commitment
7. AB TO F-VIII,CD31,CD 45 -

SPREAD
 HEMATOGENOUS SPREAD
 PARTICULARLY LUNG
 ALSO METASTASIZE TO OTHER BONE,PLEURA , BRAIN OR OTHER VISCERAL SITE
 DISCONTINUOUS FOCI OF TUMOUR WITHIN THE SAME BONE
SATELLITE
LESION
SKIP
METASTASIS
Separate focus
occurs with
Reactive
changes around
the main mass.
Outside the
Reactive
changes in
normal bone
and
hematopoietic
marrow.

PROGNOSTIC FACTORS
• UNTREATED OSA IS FREQUENTLY FATAL.
• TRADITIONALLY AGE, SEX, LOCATION, TUMOR SIZE, STAGE AND RESULT OF VARIOUS
TEST HAVE BEEN USED IN AN EFFORT TO PREDICT THE PROGNOSIS.
• THE RESPONSE TO PREOPERATIVE THERAPY IS CURRENTLY THE MOST SENSITIVE
INDICATOR OF SURVIVAL.
. SKIP METASTASIS – POOR PROGNOSIS

DIFFERENTIALS MIMICKING FEATURES DIFFERENTIATING FEATURES
1. FRACTURE CALLUS • Callus woven bone show
prominent osteoblastic rimming.
• Absence of nuclear atypia
• Cartilage with endochondral
ossification is present in callus
2. OSTEOMYELITIS • Radiographically similar • Different histological features
3. OSTEOBLASTOMA • Rimming of osteoblast • Lack infiltrative, destructive, atypical
mitoses
4. GIANT CELL
TUMOUR
• Presence of giant cells
• Specially in sacrum as
radiographically similar
appearance in sacrum
• Occurs in skeletally mature patients
with closed epiphysis.
• Usually involves the epiphyses and
extends towards the articular
cartilage
• No atypia and atypical mitoses
• Radiographic features
5.
CHONDROSARCOMA
• Low grade chondrosarcoma with
areas of ossification
• Dedifferentiated chondrosarcoma
contains an osteoblastic OS
component
• Clear cell CS produce bone imitate
OS
• Chondroblastic OS usually contain a
high grade cartilaginous component
and age grp
• Dedifferentiated CS retain low grade
CS Foci, gradual transiotion in
between 2 component and younger
age grp
• Presence of clear cells and typical

TELANGIECTATIC OSTEOSARCOMA
• ALSO K/A MALIGNANT BONE ANEURYSM, ABC LIKE OS,
HEMORRHAGIC OS
• HIGH GRADE MALIGNANT BONE FORMING TUMOR
CHARACTERIZED BY LARGE SPACES FILLED WITH OR WITHOUT
BLOOD SEPARATED BY SEPTA.
• SITE: DISTAL FEMORAL METAPHYSIS – SINGLE MOST COMMON SITE
FOLLOWED BY UPPER TIBIA THEN PROXIMAL HUMERUS.
• C/F: SIMILAR TO CONVENTIONAL OSA BUT ONE CHARACTERISTIC
FINDING IS PATHOLOGICAL FRACTURE.
• RADIOGRAPHICALLY:
 COMPLETELY LYTIC LESIONS
 INVOLVING THE METAPHYSIS WITH INFILTRATIVE DESTRUCTIVE
MARGINS

• HEMORRHAGIC
MULTICYSTIC LESION
FILLED WITH BLOOD
CLOTS DESCRIBED AS
BAG OF BLOOD.
• NO FLESHY OR
SCLEROTIC TUMOR
BONE FORMATION. 1 2

• BLOOD FILLED OR EMPTY SPACES
SEPARATED BY THIN SEPTA
SIMULATING ABC.
• SEPTA CONTAINING HIGHLY
PLEOMORPHIC MONONUCLEAR AND
MULTINUCLEATED GIANT CELLS
• ABUNDANT MITOTIC ACTIVITY
• PROGNOSIS: LIKE CONVENTIONAL
OS
• D/D
ABC:- QUITE SIMILAR , CAN BE
DIFFERENTIATED ON THE BASIS OF
PRESENCE OF MALIGNANT CELLS
WITHIN THE SEPTA.
1
2

SMALL CELL OSTEOSARCOMA
• OS COMPOSED OF SMALL CELLS WITH VARIABLE DEGREE OF OSTEOID PRODUCTION
• EPIDEMIOLOGY:- 1.5% OF OSA. (RARE)
SECOND DECADE OF LIFE.
SLIGHT PREDOMINANCE FOR FEMALE
• SITES:- METAPHYSIS OF LONG BONES.
• C/F:- PAIN, SWELLING OF SHORT DURATION
• RADIOGRAPHICALLY SIMILAR TO CONVENTIONAL OSTEOSARCOMA

• COMPOSED OF SMALL CELLS WITH SCANT
CYTOPLASM ASSOCIATED WITH OSTEOID
PRODUCTION.
• TWO TYPES:-
a) ROUND CELL TYPE –
 ROUND TO OVAL NUCLEI WITH FINE TO
COARSE CHROMATIN
 SCANT CYTOPLASM
 MITOSIS – 3-5/10 HPF.
a) SPINDLE CELL TYPE(LESS FREQUENTLY):-
 NUCLEI SHORT OVAL TO SPINDLE,
 GRANULAR CHROMATIN
 INCONSPICUOUS NUCLEOLI
 SCANTY CYTOPLASM. (2)
10X
(3)40
X

• IMMUNOHISTOCHEMISTRY
• DIFFERENTIAL DIAGNOSIS:
• SLIGHTLY WORSE PROGNOSIS THAN CONVENTIONAL OS
POSITIVE NEGATIVE
1. OSTEOCALCIN
2. OSTEONECTIN
3. CD 34
4. SMA
5. SATB2
1. FLI 1
DIFFERENTIALS DIFFERENTIATING IHC MARKERS
MALIGNANT LYMPHOMA LCA Positive
MESENCHYMAL
CHONDROSARCOMA
S-100
EWING/PNET CD99
OSTEOSARCOMA SATB2

LOW GRADE CENTRAL OSTEOSARCOMA
• ALSO K/A LOW GRADE INTRAMEDULLARY
OSTEOSARCOMA
• 1-2 % OF OS
• AGE/SEX: THIRD DECADE WITH SLIGHT FEMALE
PREPONDERANCE
• SITE: LONG BONES, PREDOMINATLY IN DISTAL FEMUR &
PROXIMAL TIBIA (KNEE)
• X- RAY: MUCH OF THE LESION IS WELL CIRCUMSCRIBED
ONLY FOCAL SCLEROTIC AREA SUGGEST AN AGGRESSIVE
GROWTH PATTERN.

• MICROSCOPIC FEATURES:
 HISTOLOGICALLY, IT IS A FIBROBLASTIC OSTEOSARCOMA WITH MINIMIAL CYTOLOGICAL
ATYPIA AND MINIMAL MITOTIC ACTIVITY.
 MDM2 POSITIVITY
• DIFFERENTIAL DIAGNOSIS:
• PROGNOSIS:
EXCELLENT BUT UP TO 15% GET TRANSFORMED TO HIGH GRADE OSA
1. FIBROUS DYSPLASIA Bland Microscopic
Appearance
• lacks permeation and cortical
destruction& invasive growth
pattern
• No Osteoid
• GNAS 1 Mutation in fribrous
dysplasia
2. DESMOPLASTIC
FIBROMA
Bland Microscopic
Appearance
• No Osteoid
3. PARAOSTEAL OS Similar Histology • Surface Location
1 2 3

PAROSTEAL OSA:- (JUXTACORTICAL OSA)
(SURFACE OSTEOSARCOMAS)
• LOW GRADE OS ARISING ON THE SURFACE OF BONE
• EPIDEMIOLOGY:- 4% OF ALL OSA
 INVOLVES YOUNG ADULTS, 3RD AND 4TH DECADE.
 SLIGHT FEMALE PREDOMINANCE.
• SITES:- 70 % -METAPHYSEAL SURFACE OF DISTAL POSTERIOR(JUXTACORTICAL) FEMUR,
OTHER SITES ARE PROXIMAL TIBIA AND HUMERUS.
• C/F:- PAINLESS SWELLING, GROWING SLOWLY, INABILITY TO FLEX THE KNEE. SOMETIMES
PAINFUL SWELLING MAY BE THERE

• LOBULATED AND OSSIFIED EXOPHYTIC MASS
(CAULIFLOWER-LIKE); ATTACHED TO METAPHYSEAL
CORTEX VIA A BROAD BASE
• CENTRALLY, THE TUMOR IS RADIODENSE
(DEMONSTRATES OSSIFICATION)
• PERIPHERALLY THERE MAY BE SMALL RADIOLUCENCIES
THAT REPRESENT LOW GRADE CARTILAGINOUS LOBULES,
FIBROUS TISSUE OR FAT.
• HERE IS NO PERIOSTEAL REACTION SINCE THE TUMOR
COMES FROM THE OUTER LAYER OF THE PERIOSTEUM
AND THEREFORE DOES NOT ELEVATE THE PERIOSTEUM.
• APPEARS TO HAVE BROAD ATTACHMENT TO
UNDERLYING CORTEX WITH A CLEFT BETWEEN
EXOPHYTIC BASE AND CORTEX AT PERIPHERY. THIS IS
REFERRED TO AS A "STRING SIGN" (CLEFT IS OFTEN ONLY
IDENTIFIABLE ON CT SCAN)
• THERE MAY BE INVASION OF THE MEDULLARY CANAL
WITH LONG STANDING DISEASE

• FIRM TO HARD LOBULATED MASS
ATTACHED TO THE UNDRELYING CORTEX
WITH BROAD BASE.
 TUMOR HAS THE TENDENCY TO WRAP
(ENCIRCLE)AROUND THE INVOLVED
BONE.
• NODULES OF CARTILAGE & SATELLITE
NODULES MAY BE PRESENT.
• OCCASIONALLY, THE CARTILAGE WILL BE
INCOMPLETE CAP-LIKE, COVERING THE
SURFACE AND THUS SUGGESTING A
DIAGNOSIS OF OSTEOCHONDROMA.
• DO NOT INVOLVE MEDULLARY CAVITY,

• LOW GRADE NEOPLASM
• WELL FORMED BONY TRABECULAE IN A
HYPOCELLULAR STROMA.
• BONY TRABECULAE ARRANGED IN
PARALLEL MANNER AND SIMULATING
NORMAL BONE.
• TRABECULAE MAY NOT SHOW
OSTEOBLASTIC RIMMING.
• SPINDLE CELLS IN THE STROMA MAY
SHOW MINIMAL ATYPIA.
1
2

1.
OSTEOCHONDROMA
• Sometimes cartilage
present at periphery
similar to
osteochondroma
• When cartilage present –
hypercellular area
• In parosteal osteosarcoma, the
chondrocytes are irregularly
arranged instead of the columnar
arrangement seen in
osteochondroma.
• The bony trabeculae in parosteal
osteosarcoma are separated by a
spindle cell proliferation, instead
of bone marrow seen in
osteochondromas
2. MYOSITIS
OSSIFICANS
• No attachment to the underlying
bone
• Histologically more active and
presence of orderly pattern of
maturation of osteoid into mature
bone (zonal phenomenon)
PROGNOSIS:- EXCELLENT WITH LOCAL RECURRENCE OCCURRING WITH INADEQUATE
EXCISION

PERIOSTEAL OSTEOSARCOMA
• ALSO K/A JUXTACORTICULAR CHONDRBLASTIC OSTEOSARCOMA
• INTERMEDIATE GRADE ,MALIGNANT ,CARTLAGE AND BONE FORMING NEOPLAM ARISING FROM THE
SURFACE OF BONE.
• PREDOMINANTLY CHONDROBLASTIC
• EPIDEMIOLOGY:- <2% OF OSA, 2ND & 3RD DECADE,
• SITES: - DIAPHYSIAL OR DIAPHYSIOMETAPHYSIAL.
 TIBIA AND FEMUR ARE MOST COMMONLY INVOLVED
• C/F:- PAINLESS MASS OR LIMB SWELLING. LATER ON PAIN..

• TUMOR ARISING FROM THE SURFACE,
LIMITED TO CORTEX ,ONLY RARELY
INVADE THE MEDULLARY CAVITY
• NON HOMOGENOUS CALCIFIED
SPICULATION DISPOSED PERPENDICULAR
TO THE CORTEX GIVING AN OVERALL
SUNBURST APPEARANCE
• CORTICAL THICKENING OR EROSION MAY
BE SEEN.
• PERIOSTEAL REACTION MAY BE PRESENT.

• THE APPEARANCE OF A MODERATELY DIFFERENTIATED CHONDROBLASTIC OSTEOSARCOMA.
 CARTILAGE COMPONENT PREDOMINATES AND MAY SHOW SOME DEGREE OF ATYPIA.
 BONY SPICULES CONSIST OF ELONGATED VASCULAR CORE SURROUNDED BY CALCIFIED OSSEOUS OR
CHONDRO-OSSEOUS MATRIX WHICH IN TURN MAY BE SURROUNDED BY NON CALCIFIED
CARTILAGINOUS GROWTH.
 PERIPHERY IS GENERALLY MADE OF FASCICLES OF SPINDLE CELLS.
 LOBULE OF CARTILAGE WITH PERIPHERAL SPINDLING.
 OSTEOID FORMATION SEEN IN CENTRE OF LOBULE
PROGNOSIS:- HAVE A BETTER PROGNOSIS THAN CONVENTIONAL OSA.
• IT IS A MALIGNANT TUMOR WITH TENDENCY TO RECUR AND METASTASIZE

1
2 BONE FORMATION IN THE CENTER OF THE
LOBULE

HIGH GRADE OSTEOSARCOMA
• VERY RARE(<1%) NEOPLASM OF HIGH GRADE
OCCURRING ON THE SURFACE OF BONE
• FEMUR IS THE MOST COMMON SITE FOLLOWED
BY HUMERUS AND TIBIA.
• RADIOLOGICALLY – LESION ON THE SURFACE OF
BONE WITH VARIABLE MINERALIZATION.
• GROSSLY- FISH FLESH APPEARANCE OF THAT OF
HIGH GRADE SARCOMA
• HISTOLOGICALLY: SIMILAR TO THAT OF
CONVENTIONAL, HIGH GRADE CYTOLOGICAL
ATYPIA AND LACE LIKE OSTEOID.

OSTEOCHONDROMA(CARTILAGENOUS
EXOSTOSIS)
• BENIGN CARTILAGENOUS NEOPLASM
• CONSISTING OF CARTILAGE CAPPED BONY PROJECTION ON THE SURFACE OF BONE, CONTAINING A
MARROW CAVITY THAT IS CONTINOUS WITH THAT OF THE UNDERLYING BONE.
• EPIDEMIOLOGY:
 ONE OF THE MOST COMMON BONE TUMOUR
 FIRST THREE DECADES OF LIFE (AVG AGE – 10 YEARS)
 NO SEX PREDILECTION.
• SITE:-METAPHYSIS OF LONG BONE- DISTAL FEMUR, UPPER HUMERUS , UPPER TIBIA AND FIBULA.

• C/F:-
 USUALLY PRESENTS AS HARD MASS OF LONG DURATION
 MAY PRESENT WITH SECONDARY COMPLICATIONS
MECHANICAL OBSTRUCTION, NERVE IMPINGEMENT, FRACTURE OF STALK
 MULTIPLE OSTEOCHONDROMAS
APPROXIMATELY 15% OF PATIENTS OF ALL OSTEOCHONDROMAS.
INHERITANCE IS AD.
• GENETICS:
 MUTATION IN EXT1 AND EXT2 TUMOUR SUPPRESSOR GENE REDUCTION IN
GLYCOSAAMINETRANSFERASE ENZYME REDUCED POLYMERIZATION OF HEPARAN SULFATE
DISRUPT CHONDROCYTE DIFFERENTIATION.
 GERM LINE MUTATION MULTIPLE TUMOURS RISK OF MALIGNANCY (5-20%)

• MUSHROOM LIKE PEDUCULATED GROWTH
PROJECTING FROM THE BONE SURFACE
• EXTENDS AWAY FROM THE NEAREST
JOINT AND POINTS TOWARDS THE
DIAPHYSIS.
• CORTEX AND MEDULLA – CONTINUOUS
WITH THAT OF UNDERLYING BONE.
• SURFACE CAP REPRESENTED BY
CARTILAGE IS NOT IDENTIFIES WITH
ROUTINE RADIOGRAPHS UNLESS
CALCIFIED; MRI IS NECESSARY.

• MAY BE SESSILE OR PEDUNCULATED.
• CARTILAGENOUS CAP MATURES INTO BONE
AND BECOMES STALK.
• CARTILAGE CAP IS USUALLY SMOOTH AND
THIN.
• AVG THICKNESS OF CARTILAGE CAP – 0.6CM
( USUALLY < 2 CMS)
• ANY IRREGULARITY OF THE CAP AND
THICKNESS MORE THAN 2 CM- INDICATIVE
OF MALIGNANCY.
Large osteochondroma of femur with
bilobed appearance

• LESION HAS THREE LAYERS- PERICHONDRIUM(FIBROUS LAYER COVERING CARTILAGE CAP), CARTILAGE AND
BONE.
• OUTER LAYER FIBROUS PERICHONDRIUM-CONTINUOUS WITH THE PERIOSTEUM OF THE UNDERLYING BONE.
• CARTILAGE CAP LAYER: SMOOTH ROUNDED LAYER, SUPERFICIAL CHONDROCYTES IN LACUNAE & TEND TO
ORGANIZE IN CORDS.
• LOWER DOWN – CHONDROCYTES UNDERGO ENDOCHONDRAL OSSIFICATION.
• FEATURES OF MALIGNANT TRANSFORMATION
 WIDE FIBROUS BAND
 MYXOID CHANGES
 INCREASE CHONDROCYTE CELLULARITY
 LOSS OF ARCHITECTURE OF CARTILAGE
 MITOTIC ACTIVITY
 NECROSIS
 CHONDROCYTE ATYPIA

DIFFERENTIALS DIFFERENTIATING FEATURES
1. PAROSTEAL
OSTEOCHONDROMATOUS
PROLIFERATION (NORA LESION)
• Usually involves small bones of hands and feet.
• 3rd & 4th decade
• Medullary component of lesion is not in
continuity with host bone
• Histologically:
1. Cartilage is hypercellular with atypia and
multinucleation
2. Chondrocytes nodules are separated by a
spindle cell proliferation.
3. Mitotic activity may present nut no atypical
2. SECONDARY
CHONDROSARCOMA
Imaging- thick and irregular cap, areas of lucency
in the cartilage part.
Gross- Bosselated appearance with cystic changes
in the cap.
Absence of stalk
M/E- infiltrate soft tissue
3. SUBUNGUAL
EXOSTOSIS(DUPUTYREN
EXOSTOSIS)
• Osteochondromatous like lesion
• Distal phalnx
• Histologically similar to BPOP.
2
3

PROGNOSIS
• EXCISION IS USUALLY CURATIVE,
• RECURRENCE IN INCOMPLETELY REMOVED LESION
• BUT MULTIPLE RECURRENCES SHOULD RAISE THE SUSPICION OF MALIGNANCY.

CHONDROMA
 A GROUP OF GENERALLY BENIGN TUMOR OF HYALINE CARTILAGE.
 THEY CAN OCCUR
 IN THE BONE ( ENCHONDROMA)
 ON THE SURFACE OF THE BONE ( PERIOSTEAL CHONDROMA ) OR
 IN THE SOFT TISSUES( SOFT TISSUE CHONDROMA).

ENCHONDROMA
• BENIGN HYALINE CARTILAGE NEOPLASM, ARISES FROM THE MEDULLARY CAVITY
• ENCHONDROMATOSIS: TWO OR MORE ENCHONDROMAS AND OCCURS IN TWO CLINICAL
SETTINGS
 90% ARE ASSOCIATED WITH OLLIER DISEASE (TWO OR MORE ENCHONDROMAS)
 10% ARE SEEN IN MAFFUCI SYNDROME (ENCHONDROMA+ HEMANGIOMAS)
• EPIDEMIOLOGY:
 WIDE AGE DISTRIBUTION , RANGING FROM 5-80 YEARS.
 MAJORITY OF PATIENTS PRESENT WITHIN THE SECOND THROUGH FOURTH DECADES OF LIFE.
 MOSTLY SOLITARY
 IN YOUNG SCHILDREN SOLITARY ENCHONDROMAS ARE RARE, WHEREAS MULTIPLE ENCHONDROMAS
ARE ENCOUTERED MORE FREQUENTLY.
 BOTH SEXES ARE EQUALLY AFFECTED.

SITES OF INVOLVEMENT:
• USUALLY METAPHYSEAL-DIAPHYSEAL IN LOCATION AND FREQUENTLY AFFECT THE SHORT
TUBULAR BONES OF THE HANDS.
• FOLLOWED BY BONES OF THE FEET AND THE LONG TUBULAR BONES, ESPECIALLY PROXIMAL
HUMERUS AND PROXIMAL AND DISTAL FEMUR.
CLINICAL FEATURES:
• IN THE SMALL BONES OF THE HANDS AND FEET TYPICALLY PRESENT AS PALPABLE SWELLINGS,
WITH OR WITHOUT PAIN.
• BECAUSE THEY OFTEN EXPAND THESE SMALL BONES AND ATTENUATE THE CORTEX, THEY
FREQUENTLY PRESENT WITH PATHOLOGICAL FRACTURES.
• LONG BONE TUMORS ARE MORE OFTEN ASYMPTOMATIC, AND ARE DETECTED INCIDENTALLY
IN RADIOGRAPHS OR BONE SCANS TAKEN FOR OTHER REASONS.

• WELL DEFINED, RADIOLUCNET TO HEAVILY
MINERALIZED, MOSTLY METAPHYSEAL
INTRAMEDULLARY MASS.
• CHARACTERISTIC MINERALIZATION PATTERN-
CONSISTING OF PUNCTATE, FLOCCULENT, RING OR
ARC PATTERN.
• IN SMALL BONES, ENCHONDROMAS CAN BE VERY
EXPANSILE, CAUSES THINING OF CORTEX –
PATHOLOGICAL FRACTURE
• CORTICAL DESTRUCTION AND SOFT TISSUE INVASION
SHOULD NEVER BE SEEN IN ENCHONDROMAS AND
WOULD BE MOST CONSISTENT CHONDROSARCOMA
• MOSTLY < 5 CMS
• WELL CIRCUMSCRIBED AND HAS THE PALE
BLUE APPEARANCE TYPICAL OF
CARTILAGE.
• C/S – WHITISH, NODULAR
CARTILAGENOUS AREA.(LONG BONE)
• SMALL TUBULAR BONE – CONFLUENT
GROWTH PATTERN
A
A
B
B

ENCHONDROMAS OF LONG BONE:
 COMPOSED OF HYPOCELLULAR LOBULATED,
MATURE, HYALINE LIKE CARTILAGE.
 LOBULES MAY BE SEPARATED BY MARROW
HEMATOPOEITIC TISSUE OR
ENDOCHONDRAL BONE.
 THE CHONDROCYTES LIE IN LACUNAE WITH
BLAND NUCLEAR FEATURES AND ARRANGED
SINGLY OR IN SMALL CLUSTERS
ENCHONDROMA OF SMALL TUBULAR
BONES:
 HYPERCELLULAR AND CONTAINS
ENLARGED NUCLEI. FREQUENT DOUBLY
NUCLEATED CELLS AND MYXOID CHANGE
IN THE MATRIX
 PRESENCE OF MYXOID CHANGE IS A SIGN OF
MALIGNANCY EXCEPT SMALL TUBULAR
BONES
1 2

LOW GRADE
CHONDROSARCOMA
• enchondromas of small
bones closely mimic
chondrosarcoma
• Hypercellular area
composed of
chondrocytes with nuclear
enlargement and
binucleation
1. C/F: Pain is present while
absent in enchondroma
unless traumatized or
fractured.
2. X-ray: Cortical
destruction with soft
tissue mass in Low Gr. CS
3. Size > 5 cms
4. Marrow permeation
present.
5. Prominent myxoid
changes+
6. Lobules of chondroid
tissue are separated by
normal hematopoietic cell
in endhondroma while by
fibrous tissue in chs.
7. Mib-1 nuclear positivity
while no positivity except
enchondormas of hand &
GENETICS: HETEROZYGOUS MUTATION IN IDH 1 & 2
PROGNOSIS: SOLITARY RARELY UNDERGO SARCOMATOUS TRANSFORMATION BUT ENDROCHONDROMATOSIS MORE
FREQUENTLY
MAFFUCCI SYNDROME – RISK OF DEVELOPING MALGNACY INCLUDING OVARIAN CA & BRAIN GLIOMA

PERIOSTEAL CHONDROMA
 BENIGN CARTILAGINOUS NEOPLASM ON THE SURFACE OF BONE.
 OCCURS IN BOTH CHILDREN AND ADULTS WITH EQUAL SEX DISTRIBUTION.
 INVOLVES LONG BONES, PROXIMAL HUMERUS IS THE CHARACTERISTIC LOCATION
AND SMALL TUBULAR BONES ARE ALSO COMMON LOCATION.
 C/F:- PALPABLE AND USUALLY PAINFUL MASS.
• PROGNOSIS:- HAVE BEEN TREATED WITH INTRALESIONAL, MARGINAL, AND EN BLOC
EXCISION, AND THE RECURRENCE MAY FOLLOW INCOMPLETE EXCISION

Smaller lesion usually < 3 cms.
Well marginated,
cortex underlying the tumor is usually thickened &
indented.
Radiology:- Radiolucent or mineralized ,
forming sharply marginated erosion
(saucerization) of the cortex. Cortex is
thickened

CHONDROBLASTOMA
• BENIGN, CHONDROID PRODUCING NEOPLASM COMPOSED OF CHONDROBLAST.
• ARISING IN THE EPIPHYSIS OF SKELETALLY IMMATURE PATIENTS.
• EPIDEMIOLOGY:
 < 1% OF ALL BONE TUMORS
 10- 25 YRS OF AGE
 MALE>FEMALE
• SITE:
 EPIPHYSIS OF LONG BONES ( BEFORE EPIPHYSEAL CARTILAGE HAS DISAPPEARED).
 DISTAL AND PROXIMAL FEMUR, FOLLOWED BY THE PROXIMAL TIBIA AND PROXIMAL HUMERUS.
 FLAT BONES (LIKE VERTEBRAE, SKULL) – OLDER INDIVIDUAL

• CLINICAL FEATURES:
 CAN BE QUITE PAINFUL
 SOFT TISSUE SWELLING, JOINT STIFFNESS, LIMITATIONS AND LIMP OF THE LIMB.
 JOINT EFFUSION SPECIALLY AROUND KNEE (MINORITY)
 TEMPORAL BONE INVOLVEMENT MAY CAUSE TINNITUS VERTIGO OR HEARING LOSS.
• RADIOGRAPHIC FEATURES:
 WELL CIRCUMSCRIBED, LYTIC, CENTRALLY OR ECCENTRICALLY PLACED IN THE EPIPHYSIS
 WITH OR WITHOUT SCLEROTIC BORDER (HELP TO DIFF FROM GIANT CELL TUMOR)
 1/3 RD CASES SHOW FOCAL CALCIFIC DEPOSITS FROM FOCAL STIPPLING TO COARSE
TRABECULAR PATTERN

• USUALLY MEASURES 3-6 CMS
• WELL CIRCUMSCRIBED, EPIPHYSEAL
GRAY MASS
• C/S: GRITTY AND GRAYISH WHITE
WITH AREAS OF HEMORRHAGE.
• ABOUT 1/3RD OF CHONDROBLASTOMA
MAY ASSOCIATED WITH ABC.

• DENSELY CELLULAR TUMOUR COMPOSED OF A MIXTURE OF MONONUCLEAR CHONDROBLAST
AND OSTEOCLAST LIKE GIANT CELLS.
• CHONDROBLAST:
 ARRANGED IN SHEETS
 OVAL NUCLEI WITH A LONGITUDINAL GROOVE- COFFEE BEAN NUCLEI (SIMILAR TO LANGERHANS CELL
HISTIOCYTOSIS).
 EOSINOPHILIC CYTOPLASM, WELL DEFINED CELL BORDER
• CHONDROID MATRIX IS PRESENT, WHICH MAY UNDERGO MINERALIZATION AND FORM
'CHICKEN-WIRE' PATTERN AROUND SINGLE CELLS.
• OSTEOCLAST-TYPE GIANT CELLS ARE SCATTERED THROUGHOUT THE TUMOR BUT ARE MOST
NUMEROUS IN AREAS OF MATRIX PRODUCTION AND HEMORRHAGE ( CONFUSED WITH GCT)

1
2
3- CHICKEN WIRE LIKE
APPEARANCE

DIFFERENTIALS MIMICKING
FEATURES
DIFFERENTIAL FEATURES
1.CHONDROMYXOID FIBROMA Histological features 1. Metaphyseal
2. Prominent lobulated myxoid
stroma
3. Lacks of calcification
2. GIANT CELL TUMOUR Presence of giant
cells
1. Skeletally mature patients
(closed epiphyseal plate.
2. Nuclear grooving absent
3. Lack chondroid matrix
4. No sclerotic rim & calcification
5. S-100 Negative
3. LANGERHANS CELL
HISTIOCYTOSIS
Nuclear grooving &
Radiographically
1. Eosinophila +
2. Lack chondroid matrix
calcification
4. ABC Chondroblastome
with prominent ABC
mimics
1. S-100 negative stromal cells

• IMMUNOCHEMISTRY:-
 EXPRESS (S-100) & VIMENTIN.
 MAY ALSO STAIN FOR KERATIN AND EPITHELIAL MEMBRANE ANTIGEN
• GENETICS:
 STRUCTURAL ANOMALIES INVOLVING CHROMOSOMES 5 AND 8
• PROGNOSIS:
 GOOD , SUCCESSFULLY TREATED WITH SIMPLE CURETTAGE AND BONE GRAFTING.
 LOCAL RECURRENCES WITHIN 2 YRS.
 MAXIMUM RECURRENCE WITH ABC.
 A SMALL % METASTASIZE TO LUNG.

CHONDROSARCOMA
(CONVENTIONAL/PRIMARY)
• MALIGNANT TUMOUR WITH CHONDROID DIFFERENTIATION
• EPIDEMIOLOGY:
 ACCOUNTS FOR 20% OF MALIGNANT BONE TUMOURS.
 THIRD MOST COMMON PRIMARY MALIGNANCY OF BONE AFTER MYELOMA AND OSTEOSARCOMA
 PEAK INCIDENCE B/W 5TH AND 7TH DECADE
 MALE > FEMALE
• SITE: DIVIDED INTO TWO ACCORDING TO LOCATION
1. CENTRAL (INTRAMEDULLARY) - USUALLY OF FLAT OR LONG BONE; ILEUM M/C SITE
2. PERIPHERAL (ON THE SURFACE OF BONE) – LOW GRADE
• C/F:
1. LOCAL SWELLING AND PAIN, ALONE OR IN COMBINATION, ARE SIGNIFICANT PRESENTING SYMPTOMS.
2. HIGH GRADE CHONDROSARCOMA METASTASIZE EARLY ,PARTICULARLY TO LUNGS.

• DIAPHYSIS OR METAPHYSIS OF LONG BONES ARE
INVOLVED.
• IN ILEUM IT INVOLVES THE PERIACETABULAR
REGION.
• FUSIFORM EXPANSION WITH CORTICAL
THICKENING OF THE BONE BUT PERIOSTEAL
REACTION IS MINIMAL OR ABT.
• CORTICAL EROSION OR DESTRUCTION IS USUALLY
PRESENT.
• MARGINS ARE POORLY DEFINED.
• COMBINATION OF EXPANSION OF BONE WITH
CORTICAL THICKENING ,ALTHOUGH PRESENT IN

MACROSCOOPIC FEATURES
• LOBULAR GROWTH PATTERN IS A CONSISTENT FINDING
• LESION C/S BLUISH-WHITE, HOMOGENOUS AND GLISTENING IN APPEARANCE CONSISTENT
WITH HYALINE CARTILAGE
• ZONES CONTAINING MYXOID OR MUCOID MATERIAL AND CYSTIC AREAS.
• EROSION AND DESTRUCTION OF THE CORTEX WITH EXTENSION INTO SOFT TISSUE MAY BE
PRESENT ESPECIALLY IN CHS OF THE FLAT BONES.
 ILL DEFFINED MARGINS
 FUSIFORM,EXPANSILE REMODELING OF BONE WITH ENDOSTEAL SCALLOPING AND
 CORTICAL DESTRCTION WITH SOFT TISSUE MASS
3 IMP
DIAGNOSTIC
SIGN

CHS GRADE
1
CHS GRADE
2
CHS GRADE
2

• AT LOW POWER , IRREGULAR SHAPED LOBULES OF CARTILAGE VARYING IN SHAPE AND SIZE, SEEN IN
A BLUE GREY CARTILAGINOUS MATRIX, SEPARATED BY FIBROUS BANDS OR PERMEATE BONY
TRABECULAE.
• CELLULARITY IS GREATER THAN THAT OF ENCHONDROMAS.
• THE CHONDROCYTES ARE ATYPICAL, VARYING IN SIZE AND SHAPE & CONTAIN ENLARGED AND
HYPERCHROMATIC NUCLEI.
• THE NUCLEI TEND TO CROWD TOGETHER AND BE DOUBLY NUCLEATED OR HYPERCHROMATIC.
• MYXOID OR MUCOID CHANGE MAY BE SEEN. ( THE PRESENCE OF MUCOID MATRIX DEGENERATION
IN <20%OF THE LESION OR HOST BONE ENTRAPMENT FAVOURS A DIAGNOSIS CHS OVER
ENCHONDROMA.

GRADING OF CHONDROSARCOMA
IT IS BASED ON THE CELLULARITY , NUCLEAR SIZE AND HYPERCHROMASIA.
GRADE 1:-
 MODERATELY CELLULAR
 HYPERCHROMATIC PLUMP NUCLEI OF UNIFORM SIZE
 OCCASIONAL BINUCLEATE CELLS
 SIMILAR TO ENCHONDROMAS. ( SMALL BONE)
GRADE 2:-
 MORE CELLULAR
 GREATER NUCLEAR ATYPIA AND HYPERCHROMASIA AND LARGE NUCLEAR SIZE.
GRADE 3:-
 MORE CELLULAR
 SOME SPINDLING AT THE PERPHERY
 PLEOMORPHIC, AND ATYPICAL THAN GRADE 2
 MITOSIS IS EASILY SEEN.(>2 /10 HOF)
• MALIGNANT TUMORS HAVING LARGE AREAS OF SPINDLING ARE LABELED AS GRADE4 –
CHONDROBLASTIC OSTEOSARCOMA OR DEDIFFERENTIATED CHONDROSARCOMA

1 2 3
CHONDROSARCOMA GRADE 1
4

CHONDROSARCOMA GTRADE III
1 2
3

GENETICS:
 AMPLIFICATION OF C-MYC ONCOGENE & EXPRESSION OF HER2NEU,C-FOS GENES,C-ERBB-2ONCOGENE
HAVE BEEN DETECTED IN CHROMOSOMES.
 IDH1/2 COMMON IN CENTRAL CHS AND HIGH GRADE CHS CANBE DISTINGUISHED FROM
CHONROBLASTOMA ON THE BASIS OF IDH MUTATION ANALYSIS.
 OVEREXPRESSION OF P-53 GENE IS LIMITED TO HIGH GRADE TYPES
 GRADE 1 – DIPLOID, GRADE II – DIPLOID OR ANEUPLOID, GRADE III – ANEUPLOID
IHC:
S-100 +VE IN GRADE I 7GRADE II WHILE –VE IN GRADE III POORLY DIFFERENTIATED AREA
PROGNOSIS:
HISTOLOGICAL GRADE IS THE SINGLE MOST IMPORTANT PROGNOSTIC FACTOR OF LOCAL RECURRENCE AND
METASTASIS.
SURVIVAL IS EXCELLENT FOR GRADE I (83%) BUT STEADILY DECREASES WITH INCREASING GRADE.
HIGH GRADE CHS METASTASIZE EARLY, PARTICULARLY TO LUNG ( L.N. METASTASES ARE PARTICULARLY
NONEXISTENT)
D/D:
ENCHONDROMA, CHONDROBLASTIC OSTEOSARCOMA

VARIANTS OF CHONDROSARCOMA
1. SECONDARY CHS
2. PERIOSTEAL CHS (JUXTA
CORTICAL)
3. MESENCHYMAL CHS
4. CLEAR CELL CHS
5. DEDIFFERATIATED CHS

VARIANT EPIDEMIOL
OGY/SITE
C/F RADIO-
GRAPHIC
MACRO-SCOPIC MICRO-SCOPIC D/D PROGNOSIS
1. SEC CHS
• Arises in
preexist-
ing lesion(
olliers ds
& mufucci
syndrome)
• Younger
than
conv.
• M/c site
is pelvis
&
shoulde
r girdle
Change
in
clinical
sign like
sudden
increase
in pain &
swelling
In pre-existing
Osteochondroma
mineralization,
increase in the
thickness of cartilage
cap, necrosis and
cystic changes are
indicative of
chondrosarcoma.
increased
cellularity and
atypical cells in
preexisting
lesion
Enchond
roma
• Dependi
ng upon
location
& grade
• Shoulde
r,
pelvis-
worse
prognos
is
2.
PERIOSTEAL
CHS
Arising on
the surface of
the bone
• Adults
(2nd-4th
decade)
• Male
• Metaphy
sis of
long
bone,
M/cly
distal
femur &
humeru
s
Pain
with or
without
swelling
• Radiolucent
lesion
arising from
bone
surface with
multilobular
appearance
• Punctate
radio
density
(calcificatio
ns)
• A large lobulated
mass(>5cms)
attached to the
surface of bone.
• C/S :lucent
glistening
appearance often
associated with
gritty areas of
enchondral
ossification or
calcification
• Histopatho-
logical
findings
similar to
that of
conventional
chondrosarc
oma.
•
Tumor
nodule seen
to permeate
soft tissue.
Perioste
al
variant
of OS
Metastasis
very rare

VARIANT Epidemiology
/site
C/F RADIO-
GRAPHIC
MACRO-
SCOPIC
MICRO-SCOPIC D/D PROGNOSI
S
3.CLEAR CELL
CHS
Rare variant
Low grade
IHC:
S-100
Collagen type
II & X
PAS
• Most
patient are
b/w 25
and 50 yrs
• M>f (3:1)
• At the end
of long
bones.
• 2/3th of
occur in
humeral or
femoral
head
Pain is
the
most
common
presenti
ng
sympto
m
• Well
defined
lytic
lesion in
epiphysea
l region.
• May
contain a
sclerotic
rim.
• Cortical
expansion
+ but
cotex is
intact.
• Well
circumscri
bed mass
• Area of
haemorrha
ge and
cystic
changes
+/-
• Elements
of
chondroid
tissue
maybe
difficult to
identify
grossly
• Low power – lobular
architecture
• Composed of tumour cells
with clear or ground glass
cytoplasm and sharply
defined borders
embedded in chondroid
matrix.
• Benign giant cells are
present at the periphery
of lobules.
• Central of the lobules
shows trabeculae of
woven bone.
Chondrobl
astoma
Osteoblast
oma
Metastatic
RCC
• Recurre
nce
rate is
high
• Lung
metast
ases or
other
skeleta
l sites
4. MESEN-
CHYMAL CHS
Rare variant
usually young
adults
Female
Pain &
Swelling
Like
conventional
CHS
• Pink and
fleshy ,
mimicking
sarcoma
• foci of
calcificatio
n usually
present
• Biphasic pattern-Island of
well differentiated
cartilage with surrounding
hypercellular area c/o
small, primitive appearing
round & spindled
mesenchymal cells.
• Transition zone present
between 2.
Dedifferen
tied CHS
Ewing
Sarocma
Embryonal
rhabdomy
osarcoma
Hemangio
pericytom
Aggressiv
e tumour
Any portion of skeleton may be
involved but definitive tendency to
involve jaw bones & ribs.
IHC: S-100 : chondroid
NSE : MESENCHYMAL component
SOX 9 – distinguish it from other
small round blue cell tumours

VARIANT EPIDEMIOLO
GY/SITE
C/F RADIO-
GRAPHIC
MACRO-SCOPIC MICRO-SCOPIC D/D PROG
NOSIS
1. DE-
DIFFER
-
ENTIAT
ED CHS
• Highly
maligna
nt
variant
 Older
patients
age b/w
50-60 yrs
 Most
common
sites
:pelvis,
femur
and
humerus
 Dedif.
Peripheral
CHS m/c-
pelvis,
scapula &
ribs
Pain is the
most
common
presenting
feature
along with
swelling
paresthesia
or
pathological
fracture.
Biomorphic
features
suggesting
dedifferentia
tion.
Dominant ill
defined lytic
lesion
within, or
adjacent to
a
mineralized
tumour-
Xray
Two different
component:
1.Cartilagenous :
centrally located,
blue-grey
lobulated area
2. Sarcomatous:
extraosseous or at
the site of #, pale
yellow to tan
brown high grade
sarcomatous area
1. Low grade
hyaline cartilage
and high grade
sarcomatous
component.
2. Sharply
demarcated with
abrupt transition
3. Cartilaginous
area: enchondroma
like to grade I or II
CHS
4. Sarcomatous
area: features of
MFH, fibrosarcoma,
OS, Andiosarcoma
etc
1.Chondrob
lastic OS
2.MFH
3.Fibro-
sarcoma
4. Mesen-
chymal CHS
5.High
grade intra-
medullary
CHS
6.Meta-
static
sarcoma to
bone
• Very
poor
• Lung
meta
-
stese
s
seen.
IHC:
Positivity for-
1.Actin
2.Desmin
3.Myoglobin
4.Alpha1 anti chymotrypsin
5.S-100
6.Exceptionally even keratin

1: Secondary chondrosarcoma in
Maffucci syndrome

CLEAR CELL CHONDROSARCOMA
1
2
3 4

MESENCHYMAL CHONDROSARCOMA
1
2 3
4

DEDIFFERENTIATED CHONDROSARCOMA
2
1 34
5

GIANT CELL TUMOR (OSTEOCLASTOMA)
• BENIGN LOCALLY AGGRESSIVE NEOPLASM
• COMPOSED OF SHEETS OF NEOPLASTIC OVOID MONONUCLEAR CELLS INTERSPERSED WITH UNIFORMLY
DISTRIBUTED LARGE, OSTEOCLAST LIKE GIANT CELLS.
EPIDEMIOLOGY:-
 4-5% OF ALL BONE TUMORS.
 AFFECTS 20- 45 YS OF PATIENTS
 IT HAS A PREDILECTION TOWARDS SKELETALLY MATURE FEMALE.
SITE:-
 MC FEMUR (LOWER END) , TIBIA(UPPER END), DISTAL RADIUS & PROXIMAL HUMERUS.
 SACRUM IS THE COMMONEST SITE FOR THE AXIAL SKELETON
C/F:-
PAIN, SWELLING AND LIMITATION OF THE JOINT ACTIVITY. OCCASIONALLY PATHOLOGICAL FRACTURE MAY BE
THERE.

• ECCENTRIC EXPANDING AREAS OF LYSIS. (WITHOUT SCLEROSIS)
• NORMALLY INVOLVES THE EPIPHYSIS AND THE ADJACENT METAPHYSIS.
• RADIOLOGICAL GRADING:- BASED ON THE MARGIN
TYPE 1:-
 (QUIESCENT) HAVE A WELL DEFINED MARGIN WITH SURROUNDING SCLEROSIS.
 VERY LITTLE CORTICAL INVOLVEMENT.
TYPE 2:-
 ACTIVE TUMOR, WELL DEFINED MARGIN BUT LACKS SCLEROSIS.
 CORTEX THINNED AND EXPANDED.
TYPE 3 :-
 AGGRESSIVE TUMOR, ILL DEFINED MARGIN
 CORTICAL DESTRUCTION AND SOFT TISSUE EXTENSION.
• OCCASIONALLY GCT HAVE A SOAP BUBBLE APPEARANCE.

• EPIPHYSEAL WELL CIRCUMSCRIBED SOFT
AND REDDISH BROWN AND FOCALLY
YELLOWISH MASS( CORRESPONDING TO
XANTHOMATOUS CHANGE.)
• CORTICAL DESTRUCTION & PRESENT AS
SOFT TISSUE MASS.
• BLOODFILLED CYSTIC SPACES ARE
SOMETIMES SEEN AND MAY MIMICK
ANEURISMAL BONE CYST.

• TUMOR IS COMPOSED OF ROUND TO OVAL POLYGONAL OR ELONGATED MONONUCLEAR
CELLS MIXED WITH NUMEROUS OSTEOCLAST LIKE GIANT CELLS WHICH MAY BE VERY
LARGE AND CONTAIN 50 TO 100 NUCLEI.
• THE NUCLEI OF THE STROMAL CELLS ARE VERY SIMILAR TO THOSE OF THE OSTEOCLASTS,
HAVING AN OPEN CHROMATIN PATTERN AND ONE OR TWO SMALL NUCLEOLI.
• MITOTIC FIGURE MAY INVARIABLY BE PRESENT(2-20) PER 10 HPF) BUT NO ATYPICAL
MITOSIS.
• THE NEOPLASTIC COMPONENT IS THE STROMAL CELLS.
• IN SOME CASES THE STROMAL CELLS MAY BE MORE SPINDLE & ARRANGED IN A
STORIFORM PATTERN

• THE GIANT CELLS OF GCT RESEMBLE OSTEOCLAST AT AT LEVELS;
 ULTRASTRUCTURALLY (RUFFLED BORDERS AND ABUNDANT MITOCHONDRIA)
 ENZYME HISTOCHEMICALLY (ACID PHOSPHATASE AND OTHER HYDROLYTIC ENZYMES)
 IHC -- POSITIVITY FOR LYSOZYME, ALPHA1 ANTITRYPSIN, ALPHA 1
ANTICHYMOTRYPSIN
• GENETICS:-
 TELOMERIC ASSOCIATION IS THE M/C ABNORMALITY, REDUCED LENGTH OF TELOMERE.
• PROGNOSIS:-
 HAVE GOOD PROGNOSIS BUT LOCAL RECURRENCES (25% OF CASES WITHIN 2 YRS) .
 RARELY METASTASIS IS SEEN IN LUNGS AND LN

MALIGNANCY IN GIANT CELL
( MALIGNANT GCT, DEDIFFERENTIATED GCT)
 HIGH GRADE SARCOMA ARISING IN A GCT( 10 MALIGNANCY) OR AT A SITE
PREVIOUSLY DOCUMENTED AS GCT( 20 MALIGNANCY)
 EPIDEMIOLOGY:- OVERALL OCCURS IN <1% OF ALL GCT, WITH A SLIGHT FEMALE
PREDOMINANCE, IN 3RD AND 4TH DECADE, WITH SAME SITE AS THAT OF GCT.
 C/F:- PAIN & SWELLING MANY YRS AFTER THE T/T OF GCT
 RADIOLOGY:-
10 MALIGNANT TUMOR HAS A LYTIC LESION EXTENDING TO THE END OF LONG
BONES.
20 MALIGNANT TUMOR HAS A DESTRUCTIVE LESION WITH POOR MARGINATION
SITUATED AT THE END OF LONG BONE ,MINERALIZATION MAY BE PRESENT.

HISTOPATHOLOGY:-
 10 MALIGNANCY:- THERE IS ABRUPT
TRANSITION TO SPINDLE CELL TUMOR WITH
MARKED CYTOLOGICAL ATYPIA.
 20 MALIGNANCY:- HIGH GRADE SPINDLE
SARCOMA WHICH MAY OR MAY NOT PRODUCE
OSTEOID. NO RESIDUAL GCT SEEN.
PROGNOSIS:-
 10 MALIGNANCY:- BETTER PROGNOSIS
 20 MALIGNANCY:- SAME AS THAT SPINDLE
CELL SARCOMA(POOR)

1. GIANT CELL
REPARATIVE
GRANULOMA
Giant cells present • Lack uniform distribution of giant
cells.
• Contain fewer nuclei and tend to
aggregate around foci of
hemorrhage.
• Stromal cells- spindle shaped
rather than round shaped.
2. GIANT CELL RICH
OSTEOSARCOMA
• Osteoid present
• Atypical mitosis+
• Pleomorphic mononuclear cells
3. ABC • Not typically involve epiphysis.
• Giants cells are arranged around
cystic spaces.
4. METATSTATIC CA
CONTAINING GIANT
CELLS
• Positive for EMA & CK (epithelial
marker)

NOTOCHORDAL TUMOUR- CHORDOMA
• MALIGNANT TUMOUR SHOWING NOTOCHORDAL DIFFERENTIATION.
EPIDEMIOLOGY:-
 1-4% OF ALL BONE TUMORS
 MOST COMMONLY PRESENT AFTER 30 YRS OF AGE, MOST COMMON BEING 6TH DECADE.
 MALE :FEMALE= 1.8:1
SITES:- SACRAL (60%), SPHENO-OCCIPITAL/NASAL (25%), CERVICAL (10%),
THORACOLUMBAR(5%)
RADIOLOGY:
• SOLITARY ,CENTRAL, LYTIC, DESTRUCTIVE LESION.
• ALMOST ALWAYS ASSOCIATED WITH SOFT TISSUE MASS.
• INTRATUMORAL CALCIFICATION MAY BE SEEN ESPECIALLY IN SACRAL TUMORS.

• EXPANSILE, LOBULATED MASS
• C/S –GLISTENING, GRAYISH TAN TO
BLUISH WHITE, MUCOGELATINOUS
TO FRIABLE, DARK RED
HEMORRHAGIC AREA
• TUMOUR EXTENT BEYOND THE
CORETX

• LOBULATED TUMORS WITH INDIVIDUAL LOBULES BEING SEPARATED BY THE FIBROUS
BANDS.
 TUMOR CELLS ARRANGED IN SHEETS, CORDS OR FLOAT SINGLY IN AN ABUNDANT
MYXOID STROMA.
 HAVE AN ABUNDANT PALE VACUOLATED CYTOPLASM (PHYSALIFEROUS CELLS) AND
SHOW MILD TO MODERATE NUCLEAR ATYPIA.
 THE CHONDROID VARIANT HAVE AREAS MIMICKING MYXOID OR HYALINE CARTILAGE.
 CHORDOMA ASSOCIATED WITH HIGH GRADE SARCOMA IS K/A DEDIFFERENTIATED
CHORDOMA.

IMMUNOHISTOCHEMICALLY:-
 BRACHYURY – VERY SENSITIVE AND SPECIFIC
 S-100,
 KERATIN-CK8 AND CK 19
 LMW CYTOKERATINS AND EMA.
 E-CADHERIN
 CATHEPSIN K.
 SHOW STRONG POSITIVITY TO 5-NUCLEOTIDASE
POTENTIAL DIAGNOSTIC IMPORTANCE
D/D:-
 CHONDROSARCOMA ( MAY HAVE A LOBULATED
PATTERN BUT LACKS THE FIBROUS SEPTA)
 MYXOPAPILLARY EPENDYMOMA ( THEY DO NOT
STAIN WITH THE EPITHELIAL MARKERS)
 METASTATIC CARCINOMA.( THEY STAIN WITH
EPITHELIAL MARKER BUT NOT WITH S-100)
PROGNOSIS:-
• HAVE IMPROVED CONSIDERABLY WITH
MODERN SURGICAL TECHNIQUE AND THE
CHONDROID VARIANT HAVE BETTER PROGNOSIS.
• ADVERSE PROGNOSTIC FACTOR INCLUDE:-
 LARGE TUMOUR SIZE,
 POSITIVE SURGICAL MARGIN
 TUMOUR NECROSIS
 HIGH PROLIFIRATIVE INDEX

EWING SARCOMA/PNET
• SMALL ROUND CELL SARCOMA (BELONG TO GROUP OF PEDIATRIC SMALL BLUE CELL TUMORS) ,SHOW VARYING
DEGREES OF NEUROECTODERMAL DIFFERENTIATION.
EPIDEMIOLOGY:-
 RARE- (6-8%) OF 10 MALIGNANT BONE TUMORS,
 COMMONLY SEEN IN 2ND DECADE AND PREDILECTION TOWARDS MALE.
SITE:-
 ANY BONE CAN BE INVOLVED.
 COMMONLY DIAPHYSIS OR METAPHYSIO-DIAPHYSIAL PART OF LONG BONES. PELVIS AND RIBS ARE
ALSO COMMON LOCATIONS.
C/F:-
 PAIN AND MASS –MOST COMMON SYMPTOM
 FEVER ANEMIA , LEUKOCYTOSIS AND RAISED ESR.

• ILL DEFINED OSTEOLYTIC LESION
INVOLVING DIAPHYSIS OF LONG BONE OR
FLAT BONE IS THE MOST COMMON
FEATURE.
• PERMEATIVE OR MOTHEATEN BONE
DESTRUCTION OFTEN ASSOCIATED WITH
"ONION-SKIN" LIKE MULTILAYERED
PERIOSTEAL REACTION IS
CHARACTERISTIC
• A LARGE ILL DEFINED SOFT TISSUE MASS
IS OFTEN ASSOCIATED.

MACROSCOPIC FEATURES:
 HAVE AN APPEARANCE OF WHITE AND FLESHY NEOPLASM.
 NECROTIC AND HEMORRHAGIC.
MICROSCOPIC FEATURES:
 SOLID SHEETS OF SMALL, UNIFORM CELLS DIVIDED INCOMPLETELY INTO CLUSTERS BY FIBROUS
SEPTA.
 SMALL CELLS - ROUND NUCLEI CONTAINING FINE CHROMATIN, SCANT CLEAR OR EOSINOPHILIC
CYTOPLASM& INDISTINCT CYTOPLASMIC MEMBRANE SMALL PUNCTATE NUCLEOLI.
 NECROSIS IS THE COMMON FINDING.(PERIVASCULAR
 IN SOME CASES HOMER-WRIGHT ROSETTES ARE PRESENT
 CLEAR CUT SPINDLING OF NUCLEUS SHOULD RULE OUT EWING SARCOMA .
 LARGE CELL VARIANT- RESEMBLE LYMPHOMA

• IMMUNOHISTOCHEMISTRY:
 CD99 - POSITIVITY IN ALMOST ALL CASES, IN CHARACTERISTIC MEMBRANOUS FASHION.
(SARCOMAS, CARCINOMAS, LYMPHOBLASTIC LYMPHOMAS, ALL
 FLI-1 – SENSITIVE , NON SPECIFIC
 LCS,SMA,MSA AND VASCULAR MARKERS- NEGATIVE
 CYTOPLASM OF THE CELLS FREQUENTLY SHOW PAS POSITIVE GLYCOGEN, BUT 20-25% CASES
ARE PAS NEGATIVE
• GENETICS:
 CHARACTERISTIC CHROMOSOMAL TRANSLOCATION T(11,22) (Q24;Q12) - 85% CASES & ,
T(21;22) (Q22;Q12) 10-15% CASES

 METASTATIC NEUROBLASTOMA– AGE < 2 YRS, CLEAR CUT ROSETTE FORMATION IN A
NEUROFIBRILLARY BACKGROUND.
 MALIGNANT LYMPHOMA– OLDER AGE , POLYMORPHIC POPULATION OF CELLS..
 ALVEOLAR/EMBRYONAL RHABDOMYOSARCOMA,
 DESMOPLATIC ROUND CELL TUMOURS.
 SMALL CELL OSTEOSARCOMA– OSTEOID MATRIX
 IMMUNOHISTOCHEMISTRY –USEFUL FOR DIFFERENTIATING .

PROGNOSIS
 GOOD IN THE MODERN ERA WITH CURRENT SURVIVAL OF 41%.
 IMPORTANT PROGNOSTIC FACTORS – STAGE, ANATOMIC SITE AND SIZE OF THE TUMOR.
 TUMORS THAT ARE LARGE, ARISE IN PELVIS, HAVE ATYPICAL FEATURES, HAVE LARGE
AMOUNT OF NECROSIS OR METASTATIC AT PRESENTATION –HAVE POOR PROGNOSIS
 P-53 OVEREXPRESSION A/W UNFAVORABLE PROGNOSIS.

SIMPLE BONE CYST(UNICAMERAL CYST)
• AN INTRAMEDULLARY, USUALLY UNILOCULAR, BONE CYST ( CAVITY) FILLED WITH
SEROUS OR SEROSAGUINEOUS FLUID.
• AGE/SEX: AFFECT MALES 3 TIMES THAT OF FEMALE IN FIRST TWO DECADES OF LIFE.
• SITE:
 PREDILECTION FOR LONG BONES PROXIMAL HUMERUS, PROX FEMUR AND PROX TIBIA
ACCOUNTING FOR 90% OF THE CASES.
 PELVIS AND CALCANEUM ARE COMMON LOCATIONS IN OLDER PATIENTS.
• ETIOLOGY
 COHEN – CAUSE OF THE CYST IS BLOCKAGE OF THE CIRCULATION (VENOUS OBSTRUCTION )
AND DRAINAGE OF INTERSTITIAL FLUID IN RAPIDLY GROWING BONE.
CLINICAL FEATURES
 INCIDENTAL DIAGNOSIS, PAIN & PATHOLOGICAL FRACTURE

• SYMMETRICALLY EXPANSILE,
RADIOLUCENT, WITH THIN
CORTICAL RIM SURROUNDING IT.
• PATHOLOGICAL FRACTURE.
• BONE FRAGMENT PRESENT IN
DEPENDENT AREA OF CYST-
FALLEN FRAGMENT SIGN.
• CYSTIC CAVITY USUALLY FILLED WITH
SEROUS OR SEROSANGUINEOUS FLUID.
• FLUID MAY BE HEMORRHAGIC IF
FRACTURE HAS OCCURRED .

• CYST WALL – C/O THIN, HYPOCELLULAR
FIBROUS TISSUE
• OCCASIONALLY CONTAINING THE FOCI OF
REACTIVE BONE FORMATION, HEMOSIDERIN
PIGMENT, CHOLESTEROL CLEFTS AND
SCATTERED GIANT CELLS.
D/D:
1. ABC 2. GCT
TREATMENT:
CURRETAGE

ANEURYSMAL BONE CYST
• DESTRUCTIVE, EXPANSILE, BENIGN NEOPLASM OF BONE COMPOSED OF MULTILOCULATED
BLOOD FILLED CYSTIC SPACES.
• AGE/SEX: COMMONLY SEEN IN 2ND AND 3RD DECADE OF LIFE, FEMALES
• SITE:
 METAPHYSIS OF LONG BONES OF UPPER AND LOWER EXTREMITIES
 POSTERIOR ELEMENTS OF VERTEBRA
 SMALL BONES OF HANDS AND FEET
 CRANIOFACIAL SKELETON
• C/F:
 PAIN & SWELLING ARE THE MOST COMMON SYMPTOMS.
 NEUROLOGICAL INVOLVEMENT IF VERTEBRAE IS INVOLVED

• IT MAY BE PRIMARY OR SECONDARY ARISING IN A BENIGN OR MALIGNANT BONE LESIONS.
THESE LESIONS MOST COMMONLY INCLUDE GIANT CELL TUMOR, OSTEOBLASTOMA,
CHONDROBLASTOMA AND FIBROUS DYSPLASIA
• RADIOGRAPHIC FEATURES:
 METAPHYSEAL.
 ECCENTRIC EXPANSION.
 PERIOSTEAL BLOW OUT OR BALLOONED OUT LESION.
 SUBPERIOSTEAL NEW BONE FORMATION.
 CORTICAL DESTRUCTION.
 CT SCAN SHOW FLUID LEVEL AND SEPTA.
 MRI GIVE CHARACTERISTIC HONEYCOMBS APPEARANCE

• WELL DEFINED AND
MULTILOCULATED HONEYCOOMB
MASS OF BLOOD FILLED CYSTIC
SPACES SEPARATED BY TAN
WHITE GRITTY SEPTA.
• MORE SOLID AREAS CAN ALSO BE
SEEN.
SOLID VARIANT OF
ABC

• ABC IS COMPOSED OF NUMEROUS CYSTIC SPACES SEPARATED BY SEPTA.
• THE SPACES FILLED WITH BLOOD OR SERUM AND THE SEPTA IS COMPOSED OF LOOSE
ARRANGEMENT OF FIBROBLASTS (MITOTICALLY ACTIVE) WITH OSTEOCLASTIC GIANT
CELLS AND THIN TRABECULAE OF RECTIVE WOVEN BONE.
• 1/3 OF CASES CONTAIN A CARTILAGE-LIKE MATRIX, CALLED 'BLUE BONE', WHICH IS NOT
COMMON IN OTHER BONE LESIONS
• OCCASIONALLY THE SOLID AREA PREDOMINATE KNOWN AS SOLID ANEURYSMAL BONE
CYST.

• HISTOLOGICAL DIAGNOSIS OF PRIMARY ABC MADE ON EXCLUSION. ANY SOLID AREA THAT IS 1CMS OR GREATER
SHOULD RAISE THE SUSPICION OF OTHER LESIONS.
• DIFFERENTIAL DIAGNOSIS
 GIANT CELL TUMOR.
 GIANT CELL REPARATIVE GRANULOMA.
 LACKS NORMALLY LARGE BLOOD FILLED CHANNELS.
 GIANT CELLS ARE FOUND THROUGHOUT THE LESION.
 SOLITARY BONE CYST
 INTRAOSSEOUS GANGLION CYST
 ADULTS, EPIPHYSIS.
 THICK CLEAR MUCIN.
 TELENGIECTATIC OSTEOSARCOMA
 ATYPICAL , MALIGNANT CELLS PRESENT.
GENETICS
17P11-13 AND/ OR 19Q22.

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