<prompt> Codmans triangle is feature of?OsteosarcomaOsteochondromaOsteoid osteomaChondrosarcoma  <response>: Ans. A. Osteosarcoma. Ref. Pathology Robbings 8thTable 21-2.a large, destructive, mixed lytic and blastic mass with indistinct infiltrating margins. The tumor frequently breaks through the cortex and lifts the periosteum, resulting in reactive periosteal bone formation Sun-burst or Sunray periosteal reaction. A triangular shadow on x-ray between the cortex and raised periosteum Codman triangle is characteristic of osteosarcomas. Osteosarcomas typically spread hematogenousiy;Osteosarcoma Outside of myeloma and lymphoma, osteosarcoma is the most common primary malignant tumor of bone, accounting for approximately 20 of primary bone cancers; Osteosarcomas occur in all age groups but some 75 of patients are younger than age 20, with a second peak occuring in the elderly, usually with other conditions, including Paget disease, bone infarcts, and prior irradiation. Men are more commonly affected than women 1.6 : 1. Although any bone can be involved, most tumors arise in the metaphyseal region of the long bones of the extremities, with almost 60 occurring about the knee, 15 around the hip, 10 at the shoulder, and 8 in the jaw. The most common type of osteosarcoma is primary, solitary, intramedullary, and poorly differentiated, producing a predominantly bony matrix. Osteosarcoma typically present as painful enlarging mass, although a pathologic fracture can be the first symptom.Rx: Despite aggressive behavior, standard Rx with chemotherapy and limb-salvage therapy currently yields long-term survivals of 60 to 70.Tumors of Bone: Tumor TypeCommon LocationsAge yr Morphology Bone-Forming BENIGN 1.Osteomaivory, cancellousFacial bones, skull40-50Exophytic growths attached to bone surface; histologically resemble normal bone2.Osteoid osteomamost common benign bone tumorMetaphysis of femur and tibia10-20Cortical tumors, characterized by pain NIDUS; histologically interlacing trabeculae of woven bone3.OsteoblastomaVertebral column10-20Arise in vertebral transverse and spinous processes; histologically similar to osteoid osteoma MALIGNANT 1.Primary osteosarcomaMetaphysis of distal femur, proximal tibia, and humerus10-20Grow outward, lifting periosteum, and inward to the medullary cavity; microscopically malignant ceils form osteoid; cartilage may also be present2.Secondary osteosarcomaFemur, humerus, pelvis40Complications of polyostotic Paget disease; histologically similar to primary osteosarcoma Cartilaginous BENIGN 1.Osteochondroma most common benign bone tumorMetaphysis of long tubular bones10-30Bony excrescences with a cartilaginous cap; may be solitary or multiple and hereditary2.ChondromaSmall bones of hands and feet30-50Well-defined single tumors resembling normal cartilage; arise with medullary cavity of bone; uncommonly multiple and hereditary MALIGNANT 1.ChondrosarcomaBones of shoulder, pelvis, proximal femur, and ribs40-60Arise within medullary cavity and erode cortex; microscopically well differentiated cartilage-like or anaplastic; Miscellaneous 1.Giant-cell tumorusually benignEpiphysis of long bone20-40Lytic lesions that erode cortex; microscopically, contain osteoclast-like giant cells and round to spindle-shaped mononuclear cells; majority are benign2.Ewing tumormalignantDiaphysis and metaphysis10-20Arise in medullary cavity; microscopically, sheets of glycogen-rich small round cells; aggressive neoplasm3.ChordomaLocally malignantAxial skeleton Sacrococcygeal bones, Clivus, cCervical vertebra20-40Expansile lytic tumor.Physalliferous cells 