Pathoma: Skeletal System Flashcards
What is achondroplasia?
impaired proliferation on the growth plate…dwarfism
Genetic mutation cause of achondopliasia?
Activating mutation in fibroblast growth factor receptor 3 (FGFR3)
Process of endochondrial bone formation?
Formation of cartilage matrix which is then replaced by bone
Process of intramembranous bone formation?
Bone formation without preexisting cartilage matrix
What are the clinical features of someone with achondroplasia?
Short extremities with normal sized head and chest
Normal mental function, lifespan and fertility
What is osteogenesis imperfecta?
Congenital defect of bone formation resulting in structurally weak bone
What is the mutation found in osteogenesis imperfecta?
Collagen type I mutation
Is the OI mutation usually AR, AD, or x linked?
AD
Clinical features of OI?
Multiple fractures of bone
Blue sclera
Hearing loss
What is osteopetrosis?
Inherited defect of bone resorption…thick, heavy bone that fractures easily
Which type of cells are poorly functioning in osteopetrosis?
Osteoclasts
Clinical features of osteopetrosis?
Bone fractures, bone marrow under production, extramedullary hematopoiesis, vision and hearing impairment, hydrocephalus, renal tubular acidosis
Why is there renal tubular acidosis in osteopetrosis?
because it is associated with a CA II mutation (which decreases reabsorption of bicarb and results in a metabolic acidosis)
What is the defect in rickets or osteomalacia?
Defective mineralization of osteoid
Which cells produce osteoid?
osteoblasts
What is the main cause of rickets or osteomalacia?
low vit D–> low Ca and PO4
What are the 3 main actions of vitamin D?
Increase intestinal absorption of Ca and PO4
Increase renal reabsorption of Ca and PO4
Increase bone resporption of Ca and PO4
What are the lab findings in osteomalacia?
Ca, PO4, PTH, alkaline phosphate
decreased Ca
decreased PO4
increased PTH
increased AP
When does someone have their peak bone mass?
30 yo
What is osteoporosis?
reduction in trabecular bone mass leading to porous bones with an increased risk of fracture
What is Paget disease of the Bone?
Imbalance between osteoblast and osteoclast function
THICK, SCLEROTIC BONE that fractures easily
What are the 3 clinical stages of paget disease of the bone?
osteoclastic
Mixed osteoblastic- osteclastic
osteoblastic
What is the histology pattern in Paget disease on biopsy?
Mosaic pattern of lamellar bone
What are the clinical features of Paget disease?
Bone pain, increasing hat size, hearing loss, lion-like facies, isolated elevated alkaline phosphatase
What is the treatment for pagets?
Calcitonin and bisphosphonates
What is osteomyelitis?
Infection of marrow and bone
What is the main organism that causes osteomyelitis?
S. aureus
Osteomeylitis in sexually active young adults?
N. gornorrhoea
Osteomyelitis in sickle cell disease?
Salmonella
Osteomyelitis in diabetic or IV drug users?
Pseudomonas
Osteomyelitis in dog/ cat bites?
Pasturella
Name a benign tumor of bone associated with facial bones and Gardener Syndrome?
Osteoma
Name a benign tumor of osteoblasts that are surrounded by reactive bone in the cortex of long bones with paint hat resolves with aspirin
Osteoid osteoma
Benign tumor of osteoblasts, surrounded by reactive bone that arises in vertebrae and is not responsive to aspirin?
Osteoblastoma
What is a tumor of bone with an overlying cartilage cap?
Osteochondroma
What osteosarcoma?
malignant proliferation of osteoblasts
Risk factors of osteosarcoma?
retinoblastoma, paget disease, radiation exposure
Where in the bone does osteosarcoma usually form?
metaphysis of long bones ( in the knee region usually)
Imaging for osteosarcoma reveals…
destructive mas with a sunburst appearance
Codman triangle
What is a tumor comprised of multinucleated giant cells and stroma cells that arise in epiphysis of long bones?
giant cell tumor
Appearance of giant cell tumors on imaging?
soap bubble
What is a malignant prolifeation of porly differentiated cells derved from neuroectoderm that is in the diaphysis of long bones
Ewing Sarcoma
What age is Ewing sarcoma usually seen in?
<15 yo
Which cancer has a t(11;22) translocation?
Ewing sarcoma
Appearance of Ewing sarcoma on xray?
“onion skin”
What is a benign tumor of cartilage that arises in the medullary of small bones of HANDS and FEET?
Chondroma
What is a malignant cartilage forming tumor that arise in the medulla of pelvis or central skeleton?
Chondrosarcoma
What is the most common tumor in bone/ cartilage?
Metastatic tumors….you see osteolytic lesions
What is a benign tumor or adipose tissue?
lipoma
What is a malignant tumor of adipose tissue?
Liposarcoma
Lipoblast is the characteristic cell of…
liposarcoma
What is a benign tumor of skeletal muscle?
Rhabdomyoma
What is a malignant tumor of skeletal muscle?
rhabdomyoscaroma
Rhabdoblast is the characteristic cell of…
rhabdomyosarcoma
Which tumors are desmin (+)?
Rhabdomyosarcoma
