Martin: Bone Tumors and Tumor-Like Lesions Flashcards
How does osteoid osteoma differ from osteoblastoma in terms of size and bone predilection?
- Osteoid osteoma: <2cm in diameter; predilection for appendicular skeleton (50% involve femur or tibia) arising in cortex
- Osteoblastoma: are >2cm and involve posterior spine (laminae and pedicles)
How does the pain and responsiveness to aspirin/NSAIDs differ between osteoid osteoma and osteoblastoma?
- Both are painful, and the pain is typically worse at night
- Osteoid osteoma DOES respond to aspirin/NSAIDs
- Osteoblastoma DOES NOT respond!
What is a radiographic clue for osteoid osteoma?
- Thick rind of reactive cortical bone; surrounding a nidus
- Osteoid osteomas elicit formaion of a tremendous amount of reactive bone
Describe the characteristic morphology of osteoid osteoma and osteoblastoma?
Haphazardly interconnecting trabeculae of woven bone that are rimmed by prominent osteoblasts
What is the bimodal age of distribution seen with osteosarcoma; which sex is most affected?
- 75% occur in pt’s <20 y/o
- 2nd peak in older adults (>65 y/o), frequently in assoc. w/ Paget disease, bone infarcts, and prior radiation
- Men more commonly affected
Which part of bones do osteosarcomas arise in and which bones are most often affected?
- Arise in metaphyseal region of long bones of extremities
- Almost 50% occur about the knee (i.e., distal femur or prox. tibia)
How do osteosarcomas typically present?
- Painful, progressively enlarging mass
- Sometimes sudden fracture is the 1st sx
What are the characteristic X-ray findings with osteosarcoma?
- Large destructive, mixed lytic and blastic mass w/ infiltrative margins
- Frequently breaks thru periosteum, resulting in reactive periosteal bone formation –> Codman triangle = elevated periosteum
Germline mutation in what gene are associated with a 1000-fold increased risk for osteosarcoma; occurence in sporadic tumors?
- Germline mutation in RB = 1000-fold ↑ risk
- This mutation is present in up to 70% of sporadic tumors
Li-Fraumeni syndrome is associated with what germline mutation; have an increased risk for what MSK pathology?
- Germline TP53 mutations
- Greatly ↑ risk of osteosarcoma
Which morphological feature of osteosarcomas is diagnostic; what is seen?
- Formation of bone by the tumor cells = diagnostic
- Neoplastic bone usually has fine, lace-like architecture but also may be deposited in broad sheets of primitive trabeculae
Osteosarcomas frequently metastasize via which route and to where?
Hematogenously to the lungs, bone, and brain
What is the most common benign bone tumor?
Osteochondroma (aka exostosis)
Majority (85%) of osteochondroma arise how and the remainder are associated with what herediatry disease?
- 85% are solitary; arise in early adulthood w/ men 3x > women
- Remainder assoc. w/ multiple hereditary exostosis syndrome, an autosomal dominant hereditary disease
Where in bone do osteochondromas arise and which bones most often affected?
- Only bones of endochondral origin and arise from the metaphysis near the growth plate
- Long tubular bones, especially near knee
- Occasionally seen in bones of pelvis, scapula,andribs
Hereditary osteochondroma (exostoses) and some sporadic types are assoc. w/ what mutations?
- Hereditary = germline loss-of-function EXT1 or EXT2
- Sporadic = ↓ expression of EXT1 or EXT2
- These genes encode enzymes that synthesize heparin sulfate gylcosaminoglycans
What is the characteristic morphology and growth pattern of osteochondromas?
- Are sessile or pedunculated w/ cap composed of benign hyaline cartilage varying in thickness
- Cortex of newly formed stalk merges w/ cortex of the host bone, so that medullary cavity of the osteochondroma and bone from which it arises are in continuity
What is a complication of osteochondroma that is more often seen in those assoc. w/ multiple hereditary exostosis?
Progression to chondrosarcoma
What are chondromas and what are they known as if they arise in the medullary cavity vs. surface of bone?
- Benign tumors of hyaline cartilage
- In medullary cavity = enchondromas
- Surface of bone = juxtacortical or subperiosteal chondromas
Which age group are enchondromas most often seen in and which bones most often affected?
- 20-50 y/o
- Appear as solitary metaphyseal lesions of tubular bones of the hands and feet
Which 2 non-hereditary disorders are characterized by multiple enchondromas; characteristics of each?
- Ollier syndrome = multiple enchondromas
- Mafucci syndrome = multiple enchondromas + angiomas –> ↑ risk of chondrosarcoma and other malignancies
Which mutations have been identified in the chondrocytes of syndromic and solitary enchondromas?
Heterozygous mutations in the IDH1 and IDH2 genes
What is the size and characteristic morphology of enchondromas; how does this differ in the non-hereditary disorders Ollier and Maffucci syndrome?
- Usually <3cm and are gray-blue and translucent
- Well-circumscribed nodules of hyaline cartilage containing benign chondrocytes
- Periphery may ossify and center can calcify and infarct
- Ollier and Maffucci: ↑ cellularity and atypia
Which age group is Chondrosarcoma most often seen in and it commonly arises in which bones?
- Usually 40 y/o + with Men 2x > female
- Axial skeleton: pelvis, shoulder, and ribs
