Bone Pathology 2.pdf

BONE PATHOLOGY II BONE TUMORS: Primary bone tumors are less common than bone metastases. Osteosarcoma is the most common primary bone cancer, Then chondrosarcoma and Ewing sarcoma. Benign tumors greatly outnumber their malignant counterparts, particularly before the age of 40 years; bone tumors in e...

BONE PATHOLOGY II BONE TUMORS: Primary bone tumors are less common than bone metastases. Osteosarcoma is the most common primary bone cancer, Then chondrosarcoma and Ewing sarcoma. Benign tumors greatly outnumber their malignant counterparts, particularly before the age of 40 years; bone tumors in elderly persons are much more likely to be malignant. Bone-Forming Tumors: Osteoma: benign lesions head and neck, including the paranasal sinuses, can occur elsewhere middle age Multiple ( Gardner syndrome,) mixture of woven and lamellar bone. cause local mechanical problems (e.g., obstruction of a sinus cavity) Cosmetic deformities, do not undergo malignant transformation Osteoid Osteoma and Osteoblastoma: benign neoplasms the teenage years and 20s, with a male predilection Distinguished from each other primarily by their size and clinical presentation. Osteoid osteomas arise beneath the periosteum in the proximal femur and tibia or posterior spinal elements (less than 2 cm in diameter,) osteoblastomas are larger. Localized pain, most severe at night, ( osteoid osteomas), relieved by aspirin. Osteoblastomas arise in the vertebral column cause pain, not responsive to aspirin. Local excision is the treatment of choice; Malignant transformation is rare unless the lesion is treated with irradiation. Osteosarcom: Osteosarcoma is a bone-producing malignant mesenchymal tumor. most common primary malignant tumor of bone After myeloma and lymphoma, 20% of primary bone cancers; 75% of patients are younger than 20 years of age, with a second peak occurring in elderly persons, Men are more affected than women most tumors arise in the metaphyseal region of the long bones of the extremities, 60% occurring about the knee, 15% around the hip, 10% at the shoulder, and 8% in the jaw. solitary, intramedullary, and poorly differentiated, producing a bony matrix The production of mineralized or unmineralized bone (osteoid) by malignant cells is essential for diagnosis of osteosarcoma Clinical Features: painful enlarging masses, pathologic fracture Radiographic imaging: a large, destructive, mixed lytic and blastic mass The tumor frequently breaks through the cortex and lifts the periosteum, resulting in reactive periosteal bone formation. A triangular shadow on the x-ray between the cortex and raised periosteum (Codman triangle) spread hematogenously; 10% to 20% pulmonary metastases, chemotherapy and limb salvage therapy Secondary osteosarcomas occur in older adults most commonly in the setting of Paget disease or previous radiation exposure Ewing Sarcoma: primary malignant small round cell tumors of bone and soft tissue 6% to 10% of primary malignant bone tumors. After osteosarcoma, it is the second most common pediatric bone sarcoma. 80% are younger than 20 years. striking racial predilection for whites; blacks and Asians are rarely affected. 95% of tumors have t(11;22)or t(21;22) Clinical Features: Painful enlarging mass in the diaphyses of long tubular bones (especially the femur) and the pelvic flat bones. Imaging studies show a destructive lytic tumor with infitrative margins and extension into surrounding soft tissues. There is a characteristic periosteal reaction with deposition of bone in an onion-skin pattern. chemotherapy and surgical excision Metastatic Disease: most common malignant tumors of bone. Pathways of spread include (1) direct extension, (2) lymphatic or hematogenous dissemination. (3) intraspinal seeding. In adults: 75% of skeletal metastases originate from cancers of the prostate, breast, kidney, and lung. In children, neuroblastoma, Wilms tumor, osteosarcoma, Ewing sarcoma, and rhabdomyosarcoma Most metastases involve the axial skeleton (vertebral column, pelvis, ribs, skull, sternum), proximal femur, and humerus, in descending order. The radiologic appearance of metastases can be purely lytic, purely blastic, or both. In lytic lesions (the metastatic cells secrete substances such as prostaglandins, interleukins, and PTHrelated protein (PTHrP) that stimulate osteoclastic bone resorption; metastatic tumors that elicit an osteoblastic response do so by stimulating osteoblastic bone formation. Most metastases induce a mixed lytic and blastic reaction. Joint pathology 1. 2. 3. 4. 5. 6. Osteoarthritis: degenerative joint disease most cases: primary Most common joint disorder part of aging fundamental feature : degeneration of the articular cartilage Oligoarticular (i.e., affecting only a few joints) joints of the hands, knees, hips, and spine 5% : SECONDARY TO: previous trauma, developmental deformity, ochronosis, hemochromatosis, or marked obesity. YOUTH MORPHOLOGY: breakdown of the cartilage matrix Chondromalacia:soft granular-appearing articular cartilage surface full-thickness portions of the cartilage are lost, subchondral bone plate is exposed and is smoothened and burnished by friction Mushroom-shaped osteophytes (bony outgrowths) develop at the margins of the articular surface PATHOGENESIS: Articular cartilage bears the brunt of the degenerative changes in osteoarthritis. Too much cytokines and growth factors that results in degradation and loss of matrix degenerating cartilage containing more water and less proteoglycan The type II collagen is diminished chondrocyte apoptosis is increased Clinical Course: beginning in 50s and 60s, slowly progressive deep, aching pain exacerbated by use, morning stiffness, crepitus and limitation in range of movement nerve root compression with radicular pain, muscle spasms, muscle atrophy, and neurologic defiits Rheumatoid Arthritis: a systemic, chronic inflammatory autoimmune disease affecting many tissues but principally attacking the joints. It causes a non suppurative proliferative synovitis progresses to destroy articular cartilage and underlying bone with resulting disabling arthritis. three to five times more common in women than in men peak incidence is in the second to fourth decades of life, PATHOGENESIS: RA is an autoimmune disease The pathologic changes are caused mainly by cytokine-mediated inflammation, with CD4 + T cells being the principal source of the cytokines Many patients also produce antibodies against cyclic citrullinated peptides (CCPs), Genetic factors: 50% linked to the HLA-DRB1 locus Environmental factors: smoking and infections 80% of patients have serum immunoglobulin M (IgM) (and, less frequently, IgA) autoantibodies that bind to the Fc portions of their own (self) IgG. These autoantibodies are called rheumatoid factor. They may form immune complexes with self-IgG that deposit in joints and other tissues, leading to inflammation and tissue damage. GOUT: Painful acute inflammatory response to tissue deposition of urate crystals Most commonly affects metatarsophalangeal joint of first toe Much more common in males than in females Serum uric acid levels are raised May be associated with chronic renal damage Pathogenesis: The mechanisms and causes are: 1. idiopathic decrease in uric acid excretion (c. 75% of cases of clinical gout) 2. impaired uric acid excretion secondary to thiazide diuretics, chronic renal failure, etc. 3. increased uric acid production due to increased cell turnover (e.g. tumours), increased purine synthesis (specific enzyme defects) 4. high dietary purine intake Renal disease is the most serious complication of gout: renal calculi chronic urate nephropathy and renal failure Gout is associated with obesity, alcoholism, hypertension, ischaemic heart disease, various forms of hyperlipoproteinaemia and impaired glucose tolerance. However, the majority of patients who have a raised blood uric acid level will never develop gout, or any of its complications.