Simple explaination
Here's a simple breakdown of what's in your notes:
Fibrous Dysplasia (top section)
Normal bone is replaced by fibrous tissue. Key points:
- X-ray looks: Ground glass/hazy, "rind sign" (thin shell of bone), "Shepherd's crook" deformity (bowing of the hip)
- Biopsy: "Chinese letter pattern" - the way the abnormal bone trabeculae look under a microscope
- Treatment: Bisphosphonates (drugs that strengthen bone)
McCune-Albright Syndrome = a special variant with 3 features:
- Polyostotic fibrous dysplasia (multiple bones affected)
- Café au lait spots (flat brown skin patches)
- Precocious puberty (early puberty)
Bone Cysts
Think of these as fluid-filled "bubbles" inside bone.
Simple Bone Cyst (SBC) vs Aneurysmal Bone Cyst (ABC)
| Feature | Simple (SBC) | Aneurysmal (ABC) |
|---|---|---|
| Locules | Single chamber | Multi-loculated (many chambers) |
| Expansion | Symmetrical | Asymmetric/ballooning |
| Position | Central (centric) | Eccentric (off-center) |
| Location | Metaphysis, proximal humerus | Metaphysis, around the knee |
| Age | 10-20 years | Same range |
| Contents | Clear/straw fluid | Blood |
X-ray Signs
- Fallen leaf sign - a chip of cortex breaks off and falls freely into the cyst (SBC)
- Trap door sign - the chip stays hinged at the cortex (SBC)
- Multiloculated lesion with growth plate involvement (ABC)
Treatment
- SBC: Aspiration + steroid injection, OR excision + bone graft
- ABC: Extended curettage with liquid nitrogen, phenol, or bone cement
Simple memory trick: SBC = "Simple, Single, Straw-colored" | ABC = "Always Blood-filled, Ballooning, eccentric"
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