pure MSK Flashcards
Osteochondroma demographys
most common benign bone lesion
usually <20 year olds
can present with mass effect, #, malignant Tx
multiple - MHE
osteochondroma features
exophytic pedunculated or sessile bone projection capped by cartilage
- cortical and medullary components
- grow away joint
- thickness of cap
DDX: bone spur (grows towards joint), periosteal lesion, BPOP/NORA (reactive lesion)
osteochondroma complication
cosmetic deformity
#
vascular/neuro compromise
bursal formation
malignant transformation (<1% solitary osteochondromas, 2-5% for HME)
sign of osteochondroma malignant Tx
continued growth after skeletal maturity
pain
intramedullary chondroid lesion DDx
enchondroma vs low grade chondrosarc
enchondroma features
benign hyaline cartilage producing tumor of medullary bone
child->adults, peak 10-30yo.
phalanges and long bones.
well defined, lucent defect
central > eccentic, may be expansile
variable chondroid matrix (not in phlanges)
cartilage lesions on MR?
lobulated, high signal, enhancement accentuates lobules
why should you not Bx an asymptomatic enchondroma?
because histologically it is the same as low grade chondrosarc!
what features favor low grade chondrosarc over enchondroma?
- older age, male, PAIN
- cartilage lesion in FLAT and Epiphysis (clear cell CS)
- > 5-6cm in diameter
- endosteal scalloping >2/3 cortex or >2/3 length
- periosteal rxn, fracture, soft tissue mass
cartilagenous bone lesions DDx
enchondroma
chondroblastoma
chondromyxoid fibroma
osteochondroma
chondrosarcoma
chondromyxoid fibroma
extremely rare
metaphysis (upper tib, femur)
- lobulated, ovoid, eccentric. sclerotic rim 80%, often expansile. no periosteal rxn, uncommon to have calcified matrix
chondroblastoma
young patients (10-20)
epiphysis or apophysis, long bone, eccentric beside physis.
- lytic, narrow TZ, cortex scalloping/thinning, expansile, metadiaphyseal periosteal rxn
- may breach cortex
- may have joint effusion
enchondroma vs bone infarct
enchondroma: internal matrix, non-sclerotic borders, may have endosteal scalloping
BI: well defined sclerotic serpiginous border. no endosteal scalloping
multiple enchondromas
Maffucci - ME + hemangioma
Ollier’s
GCT features
‘benign’, locally aggressive neoplasm of osteoclast-like giant cells - 15-25% recurrence post rx. 1-6% lung ‘mets’
mature bones, 20-30yo MC,
epiphysis of long bones, sacrum, apophyses (MC neoplasm of patella)
- ABUTS ARTICULAR SURFACE, eccentric.
- Non sclerotic border
- expansile, destruction, soft tissue component
ddx GCT
ABC (no soft tissue component)
chondroblastoma (OPEN physis, sclerotic margin, matrix)
myeloma/ mets
chondrosarc
telangiectatic OS
fluid-fluid levels in GCT ?
GCT with secondary ABC !
- ABCs are usually much more expansile than GCT, and older patients
GCT classic description?
eccentric, expansile, lytic lesion in the epiphysis extending to the articular surface without a scerotic rim, in a skeletally mature patient
ABC features
benign expansile lucent lesion <30 yo.
primary or secondary (NOF, GCT, chondroblastoma, osteoblastoma)
- very expansile
- eccentric (SBC is central!)
- metaphysis/epiphysis/apophysis location, spine
- fluid-fluid levels
fluid-fluid levels in a bone lesion
ABC, telangiectatic OS, SBC if #, GCT+ABC
secondary ABCs develop in?
NOF, GCT, chondroblastoma, osteoblastoma
sign of a secondary ABC?
expansile lesion with fluid-fluid levels in a soft tissue lesion
lytic epiphyseal lesion/physis in peds DDx
chondroblastoma
osteomyelitis
GCT (but this is CLOSED growth plate)
chondroblastoma features
epiphysis but if large, can extend into MP. Eccentric.
sharp margins. thin sclerotic im.
matrix in 25-40%
can have surrounding inflammation
osteomyelitis epiphysis features
ill-defined irregular margins, if abscess, peripheral enhancement/central portion does NOT enhance
chondroblastoma DDx
GCT (if closed growth plate, but not a lot of BM and soft tissue edema)
ABC
clear cell chondrosarc on XR (closed physis)
benign bone lesions with lots of soft tissue edema?
osteoid osteoma
osteoblastoma
chondroblastoma
osteoid osteoma definition
b enign bone tumor characterized by central nidus of osteoid, osteoblasts and variable amounts of fibrovascular stroma. nidus surrounded by dense, reactive bone
osteoid osteoma features
10-11% of benign BTs
M>F, 10-25yo.
intensely vascular, ++BM and ST edema
metaphysis/diaphysis, femur neck/posterior elements
often intracortical.
lucent nidus, dense sclerotic surrounding bone –> hard to see on MR - CT better- oval/round areas of low density.
central nidus enhances strongly
which is larger, NOF or FCD?
> 2cm length is FCD, >2cm NOF
