Section 1 - Part 4.pdf

Page 4 Saturday, September 21, 2024 8:14 PM - Neoplastic diseases of bone ○ **NOTE** ▪ The most common malignant tumor of bone, brain, liver, GI, etc. in pathology is metastases ○ Benign bone-forming tumors ▪ Osteoma...

Page 4 Saturday, September 21, 2024 8:14 PM - Neoplastic diseases of bone ○ **NOTE** ▪ The most common malignant tumor of bone, brain, liver, GI, etc. in pathology is metastases ○ Benign bone-forming tumors ▪ Osteoma □ Most commonly found in flat bones like in the skull ▪ Osteoid osteoma □ An uncommon tumor but is extremely painful □ Contains an osteoid tissue that is surrounded by a "halo" of bone formation □ Most commonly found in the metaphysis of long bones and vertebrae □ This tumor secretes prostaglandins The pain is increased with alcohol use and decreased with aspirin ▪ Osteoblastoma □ Similar to osteoid osteoma, but is NOT as painful ○ Malignant bone-forming tumors ▪ Osteosarcoma □ This is the most common primary malignant bone tumor** □ Most often occurs in the areas around the knee joint □ The 2nd most common site is the proximal humerus ○ Benign cartilage-forming tumors ▪ Osteochondroma □ This is the most common primary benign bone tumor** □ Contains a mushroom-like bulge □ Most common location is the knee joint ▪ Chondroma □ Found mostly in metacarpals and phalanges of the hands and feet ▪ Ollier's disease □ Classified as multiple enchondromas The enchondromas have a tendency to become malignant, leading to enchondromatosis ▪ Maffuci syndrome □ Classified as multiple chondromas with cavernous hemangiomas of the skin Hemangiomas are tumors of capillaries, will present as birthmarks that disappear with age Cavernous hemangiomas have a dark red wine-like 'stain' on the skin ▪ Chondroblastoma □ Commonly present in the upper femur, tibia, and humerus □ It is a slow growing tumor with sharply defined borders ○ Malignant cartilage-forming tumors ▪ Chondrosarcoma □ Classified as the 2nd most common primary tumor overall □ Occurs after the age of 20, never before puberty □ They most often metastasize to the lungs ○ Other tumors of the bone ▪ Giant cell tumor □ Classified as containing 'big bubbles' within the bone structure ▪ Ewing's sarcoma □ Classified as containing onion-skin laying lesions Exam 1 Page 1  □ Classified as containing onion-skin laying lesions ○ Primary malignant tumors found within a bone, but not of bone itself ▪ Multiple myeloma □ This is the most common primary malignant tumor found within the bone marrow that is made up of plasma cells □ This is the most common primary tumor within a bone that is seen on a radiograph □ Commonly found in the spine and ribs □ Fractures and "punched-out" lytic lesions are common ▪ Secondary metastases □ This is the most common tumor found in the bone □ Types Osteolytic ◊ ***Metastasize to the thyroid Osteosclerotic ◊ ***Metastasize to the prostate - Genetic diseases of bone ○ Osteogenesis imperfecta (OI) ▪ Aka brittle bone disease ▪ Defined as abnormal development of type I collagen ▪ 1st form of OI □ This is the most common type with an autosomal dominant inheritance □ Classified as having blue sclera and multiple fractures within bone ○ Achondroplasia ▪ The defect is in the appendicular system, where the axillary system is normal ○ Osteopetrosis ▪ Aka Marble-bone disease ▪ This defect is a failure of normal bone remodeling □ Resorption of bone is decreased which leads to abnormally dense bones ▪ Can see narrowing of the cranial nerve passageways which leads to cranial nerve palsy ○ Cleidocranial dysplasia ▪ Clinical features □ Hypoplasia or absence of clavicles □ Abnormalities of the facial skeleton □ Large number of teeth □ Bird face appearance ○ Marfan syndrome ▪ Aka cystic medial degeneration ▪ Defined as having unstable crosslinks between elastin fibers and type 1 collagen fibers ▪ Clinical features □ Increased long bone length □ Arachnodactyly □ Cystic medial necrosis of the tunica media of the aortic arch This can lead to a dissected aortic aneurysm ▪ Diagnosis □ Steinburg sign The thumb extends past the fingers folded over it □ Walker-Murdoch sign Thumb and 5th digit can connect/ overlap when wrapped around the wrist - Metabolic bone diseases ○ General information ▪ The ratio of inorganic to organic components of bone is 2:1 □ Ca is the inorganic component Exam 1 Page 2  □ Ca is the inorganic component □ Osteoid is the organic component ▪ T-score □ Normal is 1.0 to -1 □ Osteopenia is -1 to -2.5 □ Osteoporosis is < -2.5 ▪ Presents with fractures of the femoral neck and Dowager's hump (vertebral collapse) ○ Generalized Osteoporosis ▪ Type 1 Primary osteoporosis □ Defined as an increased osteoclast activity as seen in postmenopausal women ▪ Type 2 primary osteoporosis □ Defined as an overall loss of osteoblastic activity in both sexes due to age ▪ Secondary osteoporosis □ Seen in people who are Immobilized or astronauts Undergoing chemotherapy Have neoplasia or malabsorption syndromes ○ Rickets and Osteomalacia ▪ This disease is an issue with inorganic bone ▪ Rickets is seen in children due to nutritional deficiency of vitamin D ▪ Osteomalacia is seen in adults ▪ Both are due to a defective mineralization of newly formed bone ○ Scurvy ▪ This disease is an issue with organic bone ▪ Defined as a deficiency of vitamin C that leads to a failure of formation of osteoid that cannot make any matrix in bone □ Vitamin C is necessary to convert tropocollagen to collagen which is a component of an osteoid ○ Hyperparathyroidism ▪ Primary hyperparathyroidism □ Defined as parathyroid glands producing too much PTH due to benign functional tumor of the parathyroid glands □ Causes an increase in blood calcium ▪ Secondary hyperparathyroidism □ Defined as decreased levels of blood calcium due to renal failure Known as renal osteodystrophy Exam 1 Page 3