Pathoma Musculoskeletal Pathology Flashcards
What are the clinical features associated with osteogenesis imperfecta? What might it be confused with?
BITE
B = Bones - multiple fractures
I = Eye -> blue sclera from choroidal veins showing (translucent connective tissue)
T = Teeth, - abnormal dentin
E = Ears- hearing loss, due to abnormal ossicles
Confused with child abuse -> look for ITE signs
What does the growth plate look like in osteopetrosis? Why?
Growth plate has lots of residual cartilage which should have been resorbed but has not
-> overgrowth of atypical, malformed bone
This is due to osteoclast dysfunction, most commonly due to an autosomal dominant abnormality in carbonic anhydrase 2.
What are the consequences of bone overformation in osteopetrosis?
- Increased susceptibility to fractures with thick woven bones (Erlenmeyer flash deformity of ulna / radius)
- Narrowing of skull foramina -> cranial nerve deficits and hydrocephalus (foramen magnum narrowing)
- Obliteration of marrow space due to bone overgrowth
- > myelophthisic process
What will occur due to obliteration of marrow space in osteopetrosis? What is the treatment for this condition?
Anemia and pancytopenia, leading to increased susceptibility for infections.
Extramedullary hematopoiesis will cause hepatosplenomegaly.
Treatment is hematopoietic stem cell transplant -> osteoclasts are derived from monocytes.
What are the physical features of achondroplasia? Why?
Short limbs -> lack of endochondral ossification
Large head (macrocephaly) with flat nose -> intramembranous ossification is not affected (does not require a cartilage precursor)
Why is rickets different than osteomalacia? What process is occurring in endochondral ossification?
In children, the epiphyseal cartilage which is forming the physis has not closed up.
Lack of calcification of cartilage -> overgrowth of chondrocytes / wild cartilage formation, contributing to pathology of rickets
What are the findings of rickets typically seen in infancy? define: craniotabes, rachitic rosary, pigeon breast deformity, harrison groove
Typically they are head / rib cage abnormalities since they aren’t walking around (no weightbearing)
Craniotabes - head is soft and compressible
Frontal bossing - head is overgrown and protruding
Rachitic rosary - overgrowth of costal cartilage
Pigeon-breast deformity - sternum protrudes (pectus carinatum)
Harrison groove -> groove can be seen below costal margin because ribs are so weak they get pulled in
How does vitamin D deficiency present in adulthood?
Osteomalacia, which is osteopenia with loss of bone density and cortical thickness, with increased susceptibility to fractures, weakness, and bone pain.
Looser zones - pseudofractures which are linear areas of unmineralized osteoid seen in bone.
How does the third stage of Paget disease appear radiographically?
Sclerotic stage -> osteoblasts only. Bone enlargement with abnormally increased density and course bone thickening
What labs will be elevated in serum and urine in Paget disease?
- Increased collagen breakdown products (i.e. hydroxyproline) in urine / serum -> due to increased osteoclast activity (in osteolytic / first stage)
- Increased serum ALP -> very high osteoblast activity (especially third stage) - isolated finding
What are you at increased risk for due to chronic Paget disease?
- High-output cardiac failure due to increased vascularity and AV malformations in the affected bones - LOL ehab
- Osteosarcoma -> increased osteoblast activity makes this a possibility in adults
With what symptoms does osteoporosis typically present?
Typically presents with acute back pain and loss of height as the osteopenia will lead to increased fracture risk -> formation of microfractures within vertebral bodies.
Also commonly cause kyphosis, loss of height, and fractures of femoral head and distal radius
What is the risk of osteoporosis ultimately based on and when is this achieved? How can this value be increased?
Based on peak bone mass determined by age 30
- > increased by diet and exercise
- > somewhat determined genetically by vitamin D receptor variants
What is the most common way that osteomyelitis occurs / infection spreads to bone? Common spot in bone?
Minor skin or mucosal injury leads to a bacteremia which seeds bone (hematogenously spread)
Commonly seeds metaphysis, especially in children if the growth plate is open (lots of blood flow to growing growth plate, with decreased blood flow rate)
Are children or adults more likely to get septic arthritis from osteomyelitis?
Adults -> bacteria can cross the growth plate after it closes, allowing bacterial access to epiphysis
-> explains why N. gonorrhea osteomyelitis is common in sexually active young adults
What is an important cause of osteomyelitis in diabetics and IV drug abusers?
Pseudomonas aeruginosa
- > enters diabetic wounds
- > IV drug users -> directly seeds bloodstream
What is the involucrum vs sequestrum?
Sequestrum - abscess which needs to be sequestered off
InvOlucrum - new bOne formation.
What is an osteoma and where does it typically occur?
A benign, slowly enlarging tumor of cortical bone, usually arising on flat bones of skull.
Also occurs as part of Gardner syndrome (also with FAP + retroperitoneal fibromatosis).
How does an osteoid osteoma appear radiologically? How does it appear clinically?
Osteoblastic tumor of diaphysis of longbone in adolescent males, prevents with pain at night which is relieved by aspirin.
Small (<2cm), well-circumscribed, intracortical mass
The center is radiolucent -> composed of osteoid and woven bone made by osteoblasts
The outside is radiodense -> margin is formed by reactive lamellar bone
**What condition is most similar to osteoid osteoma and how do you tell them apart?
OsteoBLASToma - almost exactly the same as osteoid osteoma, except:
- Osteoblastoma is larger (>2 cm)
- Arises in vertebrae (rather than diaphysis of long bones)
- Does NOT respond to aspirin
What is an osteochondroma also called? Is it common? When does it arise? What is the feared complication?
Exostosis = “bone growing out”
It is the most common benign tumor of bone
It commonly arises sporadically in males <25. It can be multiple in younger children a hereditary autosomal dominant form
Complication: Cap can become chondrosarcoma
What is a enchondroma and who tends to get them?
Benign tumor of cartilage.
Cartilage tumors are rule-breakers -> tend to occur in young to middle-aged adults (20s-30s)
Where do enchondromas tend to appear and what do they look like on X-ray?
Tend to appear in the medulla of small tubular bones of hands and feet, contiguous with metaphysis.
They appear as well-circumscribed, mostly radioLUCENT masses made of hyaline cartilage, surrounded by a thin bony rim.
What is the most common primary non-hematopoietic bone malignancy? What syndromes is it associated with?
Osteosarcoma
Associated with mutations in Rb and TP53, which are cell cycle regulators:
- Familial Retinoblastoma
- Li Fraumeni syndrome