Pathology - Tumours Flashcards
What is an Osteochondroma/Exostosis
Bony Outgrowth capped by a cartilage cap, attached to the underlying skeleton by a bony stalk
Where do Exostoses occur?
Metaphyses near the growth plate of long tubular bones near the knee, pelvis, scapula and ribs
What is the ratio of exostoses cases that are solitary outgrowths
85%
When does exostoses occur most commonly?
First 2 decades
If malignant, what does exostoses lead to?
chondrosarcoma
What is the pathophysiology of exostosis?
EXT1 & EXT2 genes mutated which code for enzymes to make heparan sulfate glycosaminoglycans = decrease diffusion of IHH which regulates cartilage growth
State a factor that increases malignant transformation of exostoses
Multiple Outgrowths: Multiple Hereditary Exostoses Syndrome (bones may be bowed or shortened)
What is the morphology of exostoses cases?
Sessile, Pedunculated, 1-20cm, cap made of hyaline cartilage and covered in perichondrium
What is the histologic appearance of Exostoses?
Disorganised growth plate; undergoes Endochondral ossification (newly made bone forms inner portion of head and stalk
What are morphological features of chondromas?
- Well Defined
- No soft tissue invasion
- Calcification - stippled, flocculent
- Bulbous Expansions
- Complications: Fractures, Malignant Degeneration
What are histological features of chondromas?
- Mature Hyaline Cartilage (Gray-blue/translucent)
- No Cytological Atypia
- No permeation of bone trabeculae or marrow
- No Soft Tissue Invasion
What is the morphology of a simple bone cyst?
Cyst-like structure with fibrous wall
Amorphous pink material with a cementum-like appearance
What is the molecular mutation of a Simple Bone Cyst?
FUS or EWSR-1-NFATC2 fusion
What are the clinical features of a simple bone cyst?
- Benign, Fluid Containing Lesion
- Occurs in metaphyses
- 50% present as pathological fracture
Most common occurence of simple bone cysts?
4-10 years old
What is an osteoid osteoma?
Benign bone-forming tumour characterised by extensive reaction and pain disproportionate to size
Clinical features of osteoid osteoma?
- pain becomes unrelenting when untreated
- nidus in bone
Locations of Osteoid Osteoma?
Cortical Diaphyseal (65%-70%)
Femur > Tibia
Intracapsular (esp femoral neck)
Spine (10%, usually posterior elements)
EpiD of osteoid osteoma?
- 10-25 years old
- M:F = 3:1
- 4% of primary tumours
- Rarely malignant change to osteogenic sarcoma
- 20% recurrence
Treatment of Osteoid Osteoma & Osteoblastoma?
OO: Aspirin, NSAIDS, radiofrequency ablation
OB: Curettage followed by bone grafting
Imaging of Osteoid Osteoma?
- Oval Lytic Lesion (loosened lesion) in cortical bone; rounded; sclerosis
- Sclerosis may obscure underlying lytic nidus on radiograph
- Calcified nidus and cortical sclerosis (thickening) on CT
Distinguish between Osteoid Osteoma and Osteoblastoma?
Thick rim of reactive cortical bone
Features of Osteoblastoma?
Anastomosing woven bone trabaculae rimmed by abundant osteoblasts
Loose and vascular intrabacecular spaces
No malignant features (atypia, invasion, maligant osteoid)
What age does osteosarcomas occur?
10-25
How do osteosarcomas present?
Soft Tissue Swelling & Intermittent Pain
Pathological Fracture (15%)