sarcoma Flashcards
age distribution OS
PAEDS (teenagers) and >65 yo
causes of OS in different aged groups
spontaneous in paedswith rapid bone growth and associaed with Pagets disease in adults
causes of OS
previous XRT or alkylating Cx
pagets disease, Rb, werner syndrome, Li-fraumeni, bloom syndrome
most common site of osteosarcoma
the metaphysis near the growth plate
parts of the long bone
ephysis (knob like portions on the end of the bone both sup and inf), metaphysis,both sup and inf) (At the end of the diaphysis diaphysis (main shaft of bone) cartilage cap and periosteum
most common site of OS
the distal femus
most common area for mets OS
lung via hematogenous route
spread for OS
skip lesions are common and can occur in multile parts of the same bone, LN mets is rare unless located inthe trunk and blood mets for distant spread to lung
OS arise from _____ cells
msynchyme
mos common OS presentation
local swelling and pain
when is bone pain most common in OS
More common at night
how common is mets in oS
17% at Dx or 80% at 18 mos
what must be kept in mind regarding the incision after a BX in the Dx of OS
The incision should not be in the area that will be XRT
Bx offered in Dx of OS
open biopsy and core needle Bx
pattern of spread OS
symptoms that progress rapidly over a period of weeks to months is a sign of a malignancy whereas chronic symptoms suggest a benign lesion
What grade is OS typically dx at
3-4 grade in 85% cases
2 main types of OS
Surface and intramedulary OS
What subtype of OS s most common
intramedulary
what age group is intramedulary OS associated with? is it good or poor prognosis
intramedulary is associated with adolesence and is high grade/ dx late
main subtypes of intramedulary OS
Osteoblastic: Increased bone production
Chondroblastic: high degree of hyaline cartilage
Fibroblastic: contributes to the formation of connective tissue
Mixed Chondroblastic:
Subtypes of surfac OS
Parosteal- low grade, with low metastatic potential
Periosteal- intermediate grade, intermediate risk for developing mets (20% risk)
High grade surface
typical tx for OS
Typical treatment is neoadjuvant, multi-agent chemotherapy followed by surgery. (3 course CX, LSS, 6 courses Cx)
reconstruction methods for after Sx in os
Allografts: tissue graft from a donor
Endoprosthesis: artificial prostheses
Rotationplasty: knee, bottom of the femur and the upper tibia are removed, the leg is then rotated 180 degrees and reattached at the femur
in what case can sx be a sole tx in oS
low risk pts such as parosteal tumours (SURFACE OS )