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Introduction to Benign and Malignant B one Tumors

Introduction to Benign and Malignant B one Tumors. By Dr.Abdulaziz Almusallam Moderator: Dr. Abdulsalam Othman. Objective. We will take about: Embryology Histology Classification Management. Introduction .

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Introduction to Benign and Malignant B one Tumors

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  1. Introduction to Benign and Malignant Bone Tumors By Dr.AbdulazizAlmusallam Moderator: Dr. Abdulsalam Othman

  2. Objective We will take about: • Embryology • Histology • Classification • Management

  3. Introduction • The mesoderm forms nearly all the connective tissues of the musculoskeletal system, except • Within the head where neural crest also contributes connective tissues. • Each tissue (cartilage, bone, and muscle) goes through many different mechanisms of differentiation. • The 2 key developmental processes are the initial "patterning" of bone location and then the overt "differentiation" of bone through the process of ossification.

  4. Bone is formed through a lengthy process involving ossification of a cartilage formed from mesenchyme. • Two main forms of ossification occur in different bones, intramembranous (eg skull) and endochondrial (eg limb long bones) ossification. • Ossification continues postnatally, through puberty until mid 20s. Early ossification occurs at the ends of long bones.

  5. Adult Human Skeleton • The two major parts of the human skeleton are the axial (80 bones in skull, vertebra, ribs, sternum) and appendicular (126 bones in limbs, shoulders, pelvis) skeletons.

  6. Adult Human Skeleton

  7. Development Overview Mesoderm Development • Cells migrate through the primitive streak to form mesodermal layer. • Extraembryonic mesoderm lies adjacent to the trilaminar embryo totally enclosing the amnion, yolk sac and forming the connecting stalk.

  8. Paraxial mesoderm accumulates under the neural plate with thinner mesoderm laterally. This forms 2 thickened streaks running the length of the embryonic disc along the rostrocaudal axis. • In humans, during the 3rd week, this mesoderm begins to segment. • The neural plate folds to form a neural groove and folds.

  9. Segmentation of the paraxial mesoderm into somites continues caudally at 1 somite/90minutes and a cavity (intraembryoniccoelom) forms in the lateral plate mesoderm separating somatic and splanchnic mesoderm. • Note intraembryoniccoelomic cavity communicates with extraembryoniccoelom through portals (holes) initially on lateral margin of embryonic disc.

  10. Somites continue to form. • The neural groove fuses dorsally to form a tube at the level of the 4th somite and "zips up cranially and caudally and the neural crest migrates into the mesoderm.

  11. Limb Development

  12. Ossification Centres • Primary Ossification • Secondary Ossification

  13. Bone Structure Terminology : • Diaphysis – shaft • Epiphysis - expanded ends • Metaphysis - connecting region (between diaphysis and epiphysial line). • Medullary Cavity - (marrow) cavity within the bone. Can also be identified as either red or yellow marrow.

  14. Two types of bone: • Compact bone And • Trabecular bone

  15. Compact bone • (Dense) no spaces or hollows in the bone matrix visible to the eye. • Forms the thick-walled tube of the shaft (or diaphysis) of long bones, which surrounds the marrow cavity (or medullary cavity). • A thin layer of compact bone also covers the epiphyses of long bones.

  16. Trabecular bone • (Cancellous or spongy bone) consists of delicate bars (spicules) and sheets of bone, trabeculae. • Branch and intersect to form a sponge-like network. • Ends of long bones (or epiphyses) consist mainly of trabecular bone.

  17. Periosteum • Connective tissue covering the surface of bone (except articular surfaces).

  18. Endosteum • Connective tissue lining inner surface of bone.

  19. Bone Growth • Appositional growth occurs at either the periosteum (outer surface), or the endosteum (inner surface). • Osteoblasts secrete osteoid, a pre-bone material composed mainly of type I collagen that becomes mineralized. • Early bone matrix deposited in development and during repair is woven rather than lamellar in appearance and structure. • In development, there are 2 distinct types of bone formation (intramembranous and endochondral)

  20. Bone Cells:Osteoblasts • Derive from osteogenic stem cells the osteoprogenitor cells that differentiate to form pre-osteoblast then osteoblasts maturing to an osteocyte • osteoprogenitor cells - "resting cell" line the inner and outer surfaces of bone

  21. Osteocytes • Mature bone-forming cells embedded in lacunae within the bone matrix • Osteoblasts and osteocytes - secrete organic matrix of bone (osteoid), converted into osteocytes when become embedded in matrix (which calcifies soon after deposition)

  22. Osteoclasts • Bone-resorbing multinucleated macrophage-like cells • Origin- fusion of monocytes or macrophages, Blood macrophage precursor, Attach to bone matrix • Seal a small segment of extracellular space (between plasma membrane and bone surface), HCl and lysosomes secreted into this space by osteoclasts dissolves calcium phosphate crystals (give bone rigidity and strength) • Resorptive bay - (Howship's lacuna) shallow bay lying directly under an osteoclast. • Do not mistake for megakaryocytes, found in bone marrow not associated with bone matrix. • megakaryocytes are also multi-niucleated and form platelets

  23. Osteoclasts

  24. Bone Marrow • Red marrow - mainly haematopoietic (myeloid) tissue, newborn has all red marrow • Yellow marrow - mainly fat cells, found in diaphysis region of long bones • Stromal cells - all other support cells not involved in haematopoiesis

  25. Hematopoietic and stromal cell differentiation

  26. Bone Matrix The bone matrix has 2 major components: • Organic portion composed of mainly collagen Type 1 (about 95%) and amorphous ground substance. • Inorganic portion (50% dry weight of the matrix) composed of hydroxyapatite crystals, calcium, phosphorus, bicarbonate, nitrate, Mg, K, Na. • storage calcium and phosphate • regulate blood calcium levels

  27. Haversian Systems • Also called osteons • Volkmann's canals - interconnect Haversian systems Lamellae: • concentric - surrounding each Haversian System • interstitial - bony plates that fill in between the haversian systems. • circumferential - layers of bone that underlie the periosteum and endosteum Cells: • osteocytes extending cytoplasmic processes into canaliculi

  28. Bone strucrure

  29. Endochondral Ossification • The replacement of cartilage by bone.

  30. Endochondral Ossification

  31. Endochondral Ossification

  32. Intramembranous Ossification

  33. Human Fetal Head (12 week)

  34. Human Fetal Head (12 week)

  35. BONE TUMOURS

  36. CLASSIFICATION • Primary Secondary (metastases) • Primary tumors: Benign Malignant

  37. GENERAL PRINCIPLES OF RADIOLOGICAL DIAGNOSIS • AGE • SOLITARY OR MULTIPLE • SITE OF INVOLVEMENT • LOCATION WITHIN THE BONE • MARGINS • SOFT TISSUE EXTENSION

  38. BENIGN VS MALIGNANT • Narrow zone of transition • Sclerotic margin • Periosteal reaction • Tumor matrix • Pattern of bone destructionGeographic or moth eaten orpermeative

  39. BENIGN TUMOURS

  40. ENOSTOSIS • Single/ multiple • Uniformly dense • Always medullary in location • Narrow zone of transition • DD- osteoblastic metastases

  41. OSTEOMA • Slow growing • Arises from skull,paranasal sinuses and mandible • Broad base with well defined margins. • Gardners syndrome

  42. OSTEOID OSTEOMA • Male prepondarance • 2nd to 3rd decade • Diaphysis of long bones. • Round or oval area of translucency with sclerotic margin and nidus. • DD-Osteoblastoma Chronic sclerosingosteomyelitis.

  43. OSTEOBLASTOMA • Males, second decade • Similar to osteoidosteoma but >2cms • Spine & flat bones • Well defined radiolucency in cortex or medulla with cortical expansion .

  44. EXOSTOSES • Osseous outgrowth arising from bone cortex • Arises in tubular bones,near the metaphysis • Cartilage cap +, thickness 1-6mms. • Complication-Chondrosarcoma

  45. DIAPHYSEAL ACLASIA

  46. ENCHONDROMA • Originates in the medullary cavity • Commonly in the phalanges • Sharply defined lytic lesion with endosteal scalloping • Few specks of calcifications • Multiple in Ollier’s disease

  47. MAFFUCI’S SYNDROME • Multiple enchondromas +haemangiomas

  48. CHONDROBLASTOMA • 10-20 Years • Epiphysis • Well defined, radiolucent,ovallesion,with thin rim of sclerosis and cortical expansion. • Stippled calcification may present

  49. GIANT CELL TUMOUR • 20-40 YEARS • Predilection for bones adjacent to the knee and distal end of radius. • Eccentrically located zone of translucency,beneath the articular cortex • Soap-Bubble Appearance • DD-Aneurysmal bone cyst Chondroblastoma

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