Bone Pathology Duval Flashcards
What is a major cause of dwarfism?
Achondroplasia
What is the MC congenital disorder of the growth plate?
Achondroplasia
Achondroplasia genetic factor
Only 20% have family history, so 80% of cases are sporadic mutations
Pathophys of achondroplasia
- Impaired maturation of cartilage in the growth plate
- Hypoplastic disorganized chondrocyte aggregations
- Affects all bones that form from cartilage (endochondral formation)
Pathophys of osteogenesis imperfecta
Abnormal development of type I collagen
Describe osteopetrosis (pathology)
- Group of rare genetic disorders (4 variants)
- Reduced osteoclast mediate bone resorption resulting in defective bone remodelling (dense stone-like bone)
Describe osteoporosis (pathology)
- Increase in bone fragility due to a reduction in bone mass
- Localized or generalized
What causes age related bone loss? (pathology)
Decreased osteoblast activity
Morphology of osteoporosis
- Affects vertebral bodies, femoral neck
- Thin, widely separated bony trabeculae
- Normal mineral content though
- Normal osteoclast activity
How does hyperPTH affect bones?
- Increases serum Ca
- Activates osteoclasts
- Excessive osteoclastic activity
Morphology of hyperPTH (pathology)?
- Increased osteoclast activity (bone erosion)
- Reduced cortical bone and increased loose CT
- Hemosiderin deposits from previous fractures
- Brown tumor (hemosiderin, osteoclasts clump)
What factors can disrupt fracture repair? (pathology)
- Delayed healing from needing extensive remodeling (displaced/comminuted fx)
- Delayed union or non-union (from inadequate immobilization)
- Pseudarthrosis (false joint from non-union)
- Infection
- Health status (comorbidities)
Morphology of osteonecrosis (pathology)
- Dead bone w/empty lacunae, fat necrosis, Ca soaps
- Cortical bone and articular cartilage spared
- Necrotic bone acts as scaffold for new bone
MC organisms causing pyogenic osteomyelitis
- S aureus
- E coli, group B strep (neonates)
- Salmonella (sickle cell)
- Mixed flora (trauma)
What is Brodie’s abscess?
- Formed in chronic pyogenic osteomyelitis
- Residual necrotic bone (sequestrum)
- Surrounding reactive bone (involucrum)
Pathology of TB osteomyelitis: what areas affected?
- Synovium/epiphyses of long bones
- Vertebrae (Pott’s disease, psoas abscess)
Paget’s disease of bone (pathology)
- Skeletal deformities d/t intermittent exuberant osteoclast/blast activity
- Uncommon under 40 yo
- Males mainly
Pathogenesis of Paget’s disease
- Paramyxovirus-like particle in osteoclasts
- Cytokine induced osteoclast activation
- Hyper responsive osteoclasts
Morphologic phases of Paget’s disease
- Osteoclastic/lytic phase
- Mixed proliferation
- Osteosclerotic “jigsaw puzzle”
Which cancers MC metastasize to bone?
Prostate, breast, lung
What is the MC type of bone tumor?
Mets from a primary tumor
What are primary tumors of the bone?
- Osteoma
- Osteoblastoma
- Osteosarcoma (malignant)
Osteoma features (pathology)
- Head and neck
- Localized, solitary
- No malignant transformation
Osteoid osteoma/osteoblastoma features (pathology)
- Femur, tibia/vertebrae
- Young adult males
- Circumscribed, cortex
What is the MC malignant primary bone tumor?
Osteosarcoma
Classic features of osteosarcoma (pathology)
- Adolescent males
- Distal femur, proximal tibia
- Sporadic or hereditary mutation
Morphology of classic osteosarcoma
- Large, ill-defined
- Destructive
- Elevates periosteum (Codman’s triangle)
- Islands of primitive bony trabeculae (osteoid) rimmed by malignant osteoblasts
Describe osteochondroma (pathology)
- Cartilagenous tumor
- Mature bone w/cartilagenous cap
- Metaphysis of long bones
Describe chondroma (pathology)
- Benign proliferation of mature hyaline cartilage
- Small bones of hands, feet
- Young to middle aged adults
Describe chondrosarcoma (pathology)
- Older males, axial skeleton
- 2nd MC malignant bone tumor
- Glistening expansile mass in medullary cavity eroding cortex
Describe giant cell tumor of bone (pathology)
- Benign
- Proliferation of reactive osteoclast-like giant cells
- Young to middle aged females
- Epiphysis of long bones
Morphology of giant cell tumor of bone (gross vs. micro)
- Gross: solitary, dark brown (vascular), necrotic, cystic
- Micro: 2 cell types (MNGC, mononuclear)
Describe Ewing sarcoma (pathology)
- Highly aggressive tumor of children/adolescents
- Chromosomal translocation
- Diaphysis of femur, tibia, pelvis
Describe fibrous dysplasia (pathology)
- Uncommon, benign, tumor-like
- MC type is monostotic (70%)
McCune Albright syndrome (pathology)
- Part of syndrome is fibrous dysplasia
- Unilateral bone lesions
- Ipsilateral cafe au lait spots
- Precocious puberty
Morphology of fibrous dysplasia
- Circumscribed, radiolucent, sclerotic rim
- Trabecular bone replaced by fibrous tissue w/disorderly islands of malformed woven bone
What type of benign tumor can transform to malignant?
Giant cell tumor of the bone
