bone forming tumors

CLASSIFICATION OF BONE TRS

CLASSIFICATION OF BONE TUMORS

• 1) HEMATOPOIETIC (40%): Multiple Myeloma Lymphoma• 2) CHONDROGENIC (22%):(cartilage forming trs). Osteochondroma Chondroma Chondroblastoma Chondromyxoid fibroma Chondrosarcoma

• 3) OSTEOGENIC (19%): (bone forming trs) Osteoma Osteoid osteoma Osteoblastoma Osteosarcoma .4) FIBROGENIC TRS Fibrous cortical defect Desmoplastic fibroma Metaphyseal fibrous defect/NOF

• 5) FIBROHISTIOCYTIC TUMOURS Benign fibrous histiocytoma Malignant fibrous histiocytoma

6)NEUROECTODERMAL TRS Ewing sarcoma/PNET

7)UNKNOWN ORIGIN Giant cell tumour (benign) Malignant GCT.

• 8) NOTOCHORDAL TRS Chordoma Parachordoma

9)MISC. GROUP (TRS & TR LIKE LESIONS) Adamantinoma Simple bone cyst Aneurysmal bone cyst (ABC) Vascular tumours Smooth muscle tumours Lipogenic tumours

• 10) METASTATIC TRS TO BONE

Introduction to bone tumours

• Relatively uncommon.• A team approach is necessary to manage

pat. with bone neoplasm.• Cooperation among surgeon, radiologist &

pathologist is required.• Pathologist who attempts to diagnose a

bone tumor without clinical information & radiological findings is at distinct disadvantage.

• Non specific symptoms.

• Age of the patient is important.

• Exact location/site of tumor should be known.

• Solitary/ multiple.

1) Bone forming tumors

• Osteoma

• Osteoid osteoma

• Osteoblastoma

• Osteogenic sarcoma

1) Osteoma

• Seen in middle aged adults.

• Usually solitary.

• Multiple in Gardner syndrome.

• SITE : Arise on or inside skull & facial bones.

• GROSSLY : Bosselated , round to oval sessile tumors that project from subperiosteal or endosteal surfaces

• HISTOLOGICALLY: Composed of dense compact , cortical bone arranged in trabecular pattern with sharp margins. Intervening spaces are filled with hematopoietic marrow.

• D/D: Reactive bone induced by infection, trauma.

• Clinical course: Slow growing tumors of little clinical significance except

* obstruction of sinus,

* impinge on brain or eye,

* interfere with function of oral cavity,

* produce cosmetic problems,

2)Osteoid osteoma & 3)Osteoblastoma

• Histologically identical benign tumors but differ in size, sites & symptoms.

Differences

OSTEOID OSTEOMA• Size: <2cm• Age: teens & twenties• Site: appendicular skeleton• Severely PAINFUL LESIONS,

nocturnal, dramatically relieved by aspirin (prostaglandin E2 production by proliferating osteoblasts).

• Actual tumour called NIDUS.• Surrounded by a broad zone of

(sclerosis) reactive bone formation on X-ray

OSTEOBLASTOMA• Size: >2cm• Age: in adults• Site: involves spine

• Painless or if painful it is dull, achy & not responsive to salicylates

• Absence of reactive bone formation

• Variants:1)Aggressive osteoblastoma.2) Epithelioid osteoblastoma.

• D/D :Osteosarcoma.

• GROSSLY both osteoid osteoma & osteoblastoma are:

* Round /oval masses of hrg gritty tan tissue.* Small sized, well circumscribed lesions.• HISTOLOGICALLY:* Well circumscribed with discrete margins. * Composed of randomly interconnected

trabeculae of woven bone prominently rimmed by osteoblasts.

*Intertrabecular spaces filled by loose vascular C.T. containing many dilated & congested capillaries.

• Benign cytologic features of osteoblasts d/d from Osteosarcoma.

• Actual tumour called “A NIDUS” is surrounded by tremendous amt of reactive bone that encircles the lesion.

• X-RAY: NIDUS appears radiolucent, small, round area, variably mineralized.

a focus of NIDUS

osteoblastoma

Osteoid osteoma involving the fibula

Osteoid osteoma invol the upper end of femur

Osteoid osteoma (whole mount)

Nidus of Osteoid Osteoma

NIDUS of OSTEOID OSTEOMA

Osteoid osteoma

Osteoid

osteoma

OSTEOID OSTEOMA

4) OSTEOSARCOMA

Osteosarcoma

• Malignant mesenchymal tumor in which cancerous cells produce bone matrix called OSTEOID.

• Most common primary malignant tumor of bones (20%)

• Bimodal age distribution; 1) 75% in <20 yr 2) Remaining occur in old pt. with underlying conditions eg Paget disease, bone infarct, prior irradiations• Male to female ratio is 1.6:1

• Site :

* Metaphyseal region of long bones.

* 60% occur about knee.

* any bone can be involved.

* incidence in flat & long bones is equal

after age of 25 yr.

* rarely it arises in extra-skeletal soft

tissue called “extra-skeletal

osteosarcoma.”

Pathogenesis Genetic mutations. • Pt. with retinoblastomas (RB gene mutations)

have upto 1000x greater risk of developing OS.• RB gene defects are also present in 60% of

sporadic tumors.• P53, CDK4, p16, CYCLIN D1.• OS develops at the sites of greatest bone growth

where bone cell mitotic activity is max.• Large dog breeds have high incidence of OS.

• SECONDARY OS develops following pre-existing bone disease eg

• Paget disease,

• multiple osteochondromas,

• ch. osteomyelitis,

• infarct & fractures,

• previous irradiation.

Morphology of Osteosarcoma• Subtypes: 1. 1) Conventional Intramedullary OS (95%) 2) SURFACE OS (5%) a) Parosteal (juxtacortical) OS (4%) b) Periostal OS (1%) c) High grade surface OS. 2. Degree of differentiation3. Multicentricity (Synchronous, Metasynchronous)4. Primary or secondary5. Histological variants : Osteoblastic Chondroblastic Telangiectatic Fibroblastic Small cell Giant cell

Grossly

• Bulky tumors

• Gritty , gray white

• Areas of hemorrhage & cystic degeneration

• Destroy cortices & produce soft tissue masses

• Spread in medullary canal, penetrate epiphyseal plate or enter joint cavity.

Microscopy

• Neoplastic cells are pleomorphic.• Hyperchromatic nuclei.• Bizarre tumor giant cells.• Osteoid production: lace like eosinophilic

primitive bone.• Cartilage or fibrous tissue• Vascular invasion.• Necrosis.

Radiographic appearance

• Biopsy interpretation should be done alongwith radiological findings

• Large, destructive, mixed lytic & blastic mass

• Codman triangle.

• Sunburst appearance.

• The most common subtype of OS is primary, solitary, metaphyseal, intramedullary, poorly differentiated, osteoblastic.

• OS a) INTRAMEDULLARY 95%

b) SURFACE OS 5%

- Parosteal (juxtacortical)OS.= 4%

- Periosteal OS = 1%

SURFACE OS (5%)

• PAROSTEAL ( or JUXTACORTICAL) OS • - 4% of all OS. - Low grade fibroblastic OS (Grade 1 OS). - Posterior aspect of lower end of femur. - Tumour tends to wrap or ENCIRCLE around the

bone. - Hard lobulated mass attached to the underlying

cortex. Xray: heavy mineralized mass attached to the

cortex with a broad base.

Parosteal/Juxtacortical (surface) OS

• L/M of Parosteal OS.

- Well formed bony trabeculae seen in hypocellular fibrous spindle cell stroma.

- Bony trabeculae are arranged in parallel streamers

Parosteal OS

• PERIOSTEAL (SURFACE)=1%

- Is a chondroblastic OS.

- Grade 2 or 3 OS.

- Involves the diaphysis or the diaphyseal-metaphyseal area of the long bones.

X-ray: shows a spiculated pattern arising perpendicular to the cortex.

Periosteal OS

osteosarcoma

Periosteal(Surface) OS

Osteosarcoma (femur)

Osteosarcoma (humerus)

osteosarcoma

OSTEOSARCOMA

OS OF FEMUR LOWER END

Telangiectatic OS of patella

Osteosarcoma showing abundant OSTEOID deposition

OSTEOSARCOMA

Osteoblastic OS

Chondroblastic OS

TELENGIECTATIC OS

Telengiectatic OS

Epithelioid OS

Small cell OS

Giant cells in OS

Clinical course

• Painful enlarging masses

• Pathological fracture

• Mets to lungs, bones , brain

• Chemotherapy & limb salvage therapy