What is your first suspicion when seeing a cancerous lesion in bone?
Metastatic lesion. Primary bone tumors are quite rare; 0.2%.
How do bone lesions present clinically?
Often asymptomatic, but sometimes with pain, palpable mass, or pathologic fracture.
Describe some characteristic bone lesions of the following age groups:
Children: Osteosarcoma & Ewing's sarcoma :(
Young adults: Giant cell tumor
Recall the three different sites of lesions in long bones. See if you can name lesion characteristic to each region.
Epiphysis (eg Giant cell tumor)
Metaphysis (eg Osteosarcoma, many others)
Diaphysis (eg Ewing's sarcoma)
Describe how bone tumors present on X-ray imaging.
Benign or slow-growing tumors feature a sclerotic region (distinct rim), while malignant growths are more ill-defined.
Characteristic matrix formation may be present (eg solid, ivory-like pattern of bone deposition, or rings/arcs of cartilage).
Distinguish between osteoid osteomas and osteoblastomas.
Both are benign. Very similar histologies.
Osteomas are smaller, cause night pains, are responsive to aspirin, and have a clear lesion edge.
Osteoblastomas are larger, do not respond to aspirin, have a more mottled appearance and may affect vertebrae.
How common is it?
Who is at greatest risk?
The most common bone sarcoma, but still exceedingly rare (~2k/yr)
Incidence: M>F, mean age 15.
Describe some possible causes of osteosarcoma.
Why is their prognosis so poor?
Inherited mutations of Rb/p53, or overexpression of MDM2/INK4/p16.
They tend to be clinically silent until after metastasis to lungs.
How does it appear on X-ray?
What is a codman's triangle?
It is poorly delineated with marked bone/cortical destruction. May have local bone or cartilage remodeling.
A codman's triangle is an extension of periosteum being pulled away by the rapidly growing tumor.
How is it treated?
Surgical resection (ideally limb-sparing), and chemotherapy.
What is the most common tumor of cartilage (and bone, for that matter)?
Describe its pathogenesis and characteristics.
Autosomal dominant inheritance of EXT-1 mutation (8q24) results in metaphyseal tumors with bony spurs.
Distinguish between enchondromas and periosteal chondromas.
Both are benign cartilage tumors. Enchondromas are within bones (intramedullary), while periosteal chondromas are juxtacortical.
Where do they typically appear?
How are they usually diagnosed and treated?
In the appendicular skeleton (eg phalanges).
Accidentally! Usually asymptomatic, but feature cortical thinning and replacmeent with cartilage. Treatment only indicated if lesion shows changes or symptoms.
Distinguish between Ollier's disease and Maffucci's syndrome.
These are both conditions that result in multiple chondromas, probably resulting from IDH1/2 mutations. Both may cause skeletal malformation.
Ollier's disease are regionally distributed.
Maffucci's syndrome also features angiomata, and is generally higher risk for malignant transformation.
Who is at highest risk for a chondrosarcoma?
How common are they?
Old fogies; peaks during 6th-7th decades.
Second most common bone tumor (presumably most common cartilaginous tumor)
How do they present in imaging?
Medullary, "popcorn-like" lesions with calcifications. Cortical erosion with soft tissue extension.
Pleomorphism and high cellularity (stage 3 > 2 > 1). Binucleation with myxoid changes.
How is its grading determined?
Describe its 5-year outlook.
Degree of cellularity and atypia. (what about TNM?)
Good prognosis for stages 1, 2. <30% for stage 3 due to pulmonary metastasis.
What is a fibroma?
Describe their characteristics.
What are their symptoms?
A cortical defect resulting in a benign connective tissue tumor.
Metaphyseal, lytic with sclerotic border. 25% are multifocal. "Starry-sky" histology.
Occasionally pathologic fracture due to integrity loss.
What is a fibrous dysplasia?
Distinguish between monostotic and polyostotic dysplasia.
Developmental defect resulting in fibrous bone.
Monoostotic: Seen in adolescents. Common, affects ribs, mandible, & femur.
Polyostotic: Seen in infancy & early childhood. Causes crippling deformity.
Describe its pathogenesis.
What is its gender preference?
Inherited GNAS mutation causes polyendocrinopathy, cafe-au-lait spots, and polyostotic fibrous dysplasia.
F > M
Describe their appearances on X-ray.
Describe their appearances on histology.
Thinned cortex circumscribing an expanse. "Ground glass" appearance.
Trabeculae are haphazard/curvilinear ("chinese characters"). No osteoblastic rimming.
At what region of bone do they occur?
Describe their radiographic appearance.
At the diaphysis of long bones.
"Moth-eatn" destruction with large soft-tissue mass. "Onion-skin" pattern of perosteal response.
How would this sarcoma look on gross analysis & histology?
Hemorrhagic with necrosis. Histology: Sheets of CD99+ small round blue cells. Abundant glycogen?
Describe their pathogenesis. What is the mutation?
How are they treated?
85% feature t(11;22); fusion of EWS with FLI-1 TF.
Like any other malignant bone tumor: Surgery & chemotherapy, radiation if needed. Similar prognosis to osteosarcoma?
Giant Cell Tumor
Who is at highest risk?
Describe their distribution & behavior.
Giant Cell Tumor
Young adults; F > M
Epiphyseal. Benign but locally aggressive.
What are some typical sources of metastatic bone lesions?
80% belong to BLT-KP: Breast, Lung, Thyroid, Kidney & Prostate.