Bone Tumours Flashcards
What is the epidemiology of bone tumours?
Very RARE; can be benign or malignant
o Malignant tumours are 60 x less common than lung cancer
o Primary malignant bone tumours are more common in children and young adults
o Site predilection – around the knee is most common
What is the clinical features of bone tumours?
Pain
Deformity
Swelling
Fracture
What is relevant in the history of bone tumours?
Age
History of trauma
Site
Multiple lesions
Duration
Associated disease
How do you suspect bone tumours?
· Diagnosis = X-Ray
o Evaluate site, size & margin of lesion
o Solitary or multiple lesions
o Extension into the soft tissue
o Associated disease or fracture
· If primary bone tumour suspected, refer the patient urgently to a specialist centre
How do you diagnose bone tumours?
Diagnosis is through an XR and a biopsy
o US-guided Jamshidi needle biopsy
o Open biopsy for inaccessible lesions
o Imprint (cytology) preparations useful
What are the tumours like conditions?
o Fibrous dysplasia
o Metaphyseal fibrous cortical defect/non-ossifying fibroma
o Reparative giant cell granuloma
o Ossifying fibroma
o Simple bone cyst
Describe fibrous dysplasia
· More common in females; age <30yo
· Mono-ostotic is more common than poly-ostotic
· Site: any bone (ribs and proximal femur are most common)
· X-ray appearance: ‘soap bubble’ osteolysis
· <1% will undergo malignant transformation
· Caused by a mutation in a G-protein (GNAS mutation chr20; q13)
· If multiple bones affected it is likely to be benign (unless it is metastatic cancer)
· McCune Albright Syndrome = polyostotic fibrous dysplasia + rough border café au lait spots on the skin
What are the histological features of fibrous dysplasia?
· Histological features = marrow is replaced by fibrous stroma with rounded trabecular bone (used to be called Chinese letters)
· Fibrous dysplasia may be aesthetically unpleasant so patients may want to have it removed -> it can be removed with a very small margin (because it is benign)
· Fibrous Dysplasia in the Femoral Head (Shepherd’s Crook)
o Microfractures leads to a change in shape
What are the benign bone tumours?
Cartilaginous (Osteochondroma, endochondroma, chondroblastoma)
Bone forming (osteoid osteoma, osteoblastoma, osteoma)
Describe giant cell tumours
· Site = epiphysis with metaphyseal extension / ends of long bones (esp. around knee)
· Age = 20-40 years; FEMALES
· X-Ray = lytic appearance
· Histology: Osteoblast = build bone
o Osteoclasts on a background of spindle/ovoid cells Osteoclast = break down bone
· Can be locally aggressive, may recur and can metastasise
· It is called ‘Giant Cell’ because it is composed mostly of osteoclast giant cells, but they are NOT the neoplastic cells (the tumour cells are the stromal cells)
Describe metastatic bone tumours
· MOST COMMON malignant bone tumour (metastases are very rare below the elbow and below the knee)
· Cancers that spread to the bone:
o Adults
§ Breast Prostate Lung
§ Kidney Thyroid (myeloma will also be part of the differential)
o Children
§ Neuroblastoma Wilm’s tumour Osteosarcoma
§ Ewing’s sarcoma Rhabdomyosarcoma
· Stains can be used to identify the primary (e.g. PSA immunohistochemistry)
What are the malignant bone tumours?
Three types of malignant bone tumours:
o Osteosarcoma -> forms bone
o Chondrosarcoma -> forms cartilage
o Ewing’s sarcoma/PNET -> undifferentiated mesenchymal tumour
§ Primitive peripheral neuroectodermal tumour
Describe an osteosarcoma
the most common bone sarcoma
o Age: 10-30 years; MALES
o Mainly occurs at the end of long bones (e.g. knee)
§ Older patients may get it in their jaw
o XR findings:
§ Metaphyseal Permeative
§ Lytic Elevated periosteum (Codman’s triangle)
o Histology:
§ Malignant mesenchymal cells ± bone and cartilage formation
§ You can also use a stain for ALP
o Prognosis: POOR (60% 5-year survival)
o Classification
§ Site within the bone (e.g. intramedullary, intracortical, surface)
§ Degree of differentiation (high, intermediate or low)
§ Multicentricity (synchronous or metasynchronous)
§ Primary or secondary
What is a chondrosarcoma
o Malignant cartilage producing tumour
o Age: >40 years
o Site: axial skeleton, pelvis, proximal femur, proximal tibia
o X-Ray = Lytic with fluffy calcification
o Histology:
§ Malignant chondrocytes with or without chondroid matrix
§ May differentiate to high grade chondrosarcoma
o Prognosis: 70% 5-year survival
o Classification
§ Site: intramedullary, juxtacortical
§ Histology: conventional (myxoid [composed of clear, mucoid substance] or hyaline), clear cell (low grade), dedifferentiated (high grade), mesenchymal
What is an ewings sarcoma?
(PNET) – often missed due to diagnosis of osteomyelitis
o Highly malignant small round cell tumour
o Age: <25 years, ~15yo median
o Site: diaphysis/metaphysis of long bones, pelvis
o X-Ray:
§ Onion skinning of the periosteum
§ Lytic with or without sclerosis
o Histology:
§ Sheets of small round cells à
o Prognosis: 75% 5-year survival
o Associated with a specific chromosomal translocation 11:22 (EWSR1/FLI1) (q24; q12)
o Lots of immunostaining is used to exclude other types of bone tumour
What chromosomal translocations cause bone tumours?
What are the prognostic factors of bone tumours?
What is the staging for bone tumours?
