1. Bone tumors

2. Cartilage forming tumors Chondroma Benign tumors of hyaline cartilage probably develop from slowly proliferating rests of growth plate cartilage Age: 30-50 Site: located in the metaphyseal region of tubular bones ( short tubular bones of the hands and feet) Usually solitary But may multiple in: Ollier disease : multiple chondromas invo lving one side of the body Maffucci syndrome: Multiple chondrmas with soft benign vascular tumors( angiomas) of soft tissue. Enchondromas : arise within the medulla Juxtacortical chondromas: arise on the bone surface

4. Osteochondroma Osteochondromas are also called exostoses It is the most common benign tumor of bone Age: 10-30 Site: metaphysis of long tubular bones, especially about the knee Male-to-female ratio of 3 : 1 Benign cartilage-capped outgrowths attached by a bony stalk to the underlying skeleton.

5. Development over time of an osteochondroma beginning with an outgrowth from the epiphyseal cartilage

6. Solitary osteochondromas are usually first diagnosed in late adolescence and early adulthood Usually follow a benign course. Multiple osteochondromas become apparent during childhood, occurring as multiple hereditary exostosis, an autosomal dominant disorder. Rare sarcomatous change.

7. Chondrosarcoma Malignant bone forming tumor. Age: most patients are age 40 or older Site: Arise in the pelvis, shoulder, and ribs Men to female ratio: 2-1. Classified according to site and histologic variants - intramedullary - juxtacortical Metastasize hematogenously to the lungs and skeleton

8. Miscellaneous Tumors A. Giant cell tumors (osteoclastoma ) Locally malignant tumor of bone Age: occurs between 20 – 40 years of age. Site: arises in the ends of long bones particularly in relation to knee joint, jaw, radius and clavicle. X ray : large, lytic, and eccentric (soap bubble appearance)

9. Causes eccentric expansion of the affected bone and becomes covered by a thin shell of bone that yields under pressure giving (egg shell crackling). Infiltrates the surrounding tissues. The cut section shows areas of hemorrhage, necrosis and cyst formations 4% metastasize to the lungs Complications: 1- Pathological fracture 2-It may change into frankly malignant tumor

10. B. Ewing sarcoma Anaplastic malignant bone tumor Age: 10-20 Site: Diaphysis of femur, tibia, ribs and pelvis are the favored sites. Male predominance Characterized by an 11;22 translocation It follows an extremely aggressive course with early metastases Miscellaneous Tumors

11. Tumor-like lesions Fibrous bone defect 30-50% of all children older than age 2 Developmental defects rather than true neoplasms. Majority are smaller than 0.5 cm and arise in the metaphysis of the distal femur or proximal tibia 50% are bilateral or multiple Larger lesions (5-6 cm) develop into nonossifying fibromas.

12. Fibrous dysplasia Unknown origin and develops at any age in the long bones. Pathology: Fibrous proliferation intermixed with poorly formed, haphazardly arranged trabeculae of woven bone (not line by osteoblasts) progressively replace normal bone. Types: a- Monostotic: Affecting one bone. b- Polystotic: Affecting more than one. The affected part is expanded by grey white fibrous tissue which replaces the medulla and produce thinning of the cortex. Complications: Deformity and pathological fractures. Rarely it transforms into fibrosarcoma.

13. 75% of bone metastasis originate from Cancers of prostate breast kidney lung thyroid Metastatic lesions are multifocal Produce a lytic and or blastic reaction

14. Bone metastasis