MSK - Bony Lesions Flashcards
Causes of osteoblastic mets
- Prostate
- Breast - often mixed lytic and sclerotic
- Mucinous tumours
- Carcinoid
- Treated lytic mets
What is Ollier’s Disease?
What is Mafucci disease?
- Multiple enchondromatosis, asymmetric distribution, hands, skeletal deformity, predisposed to fracture
- Non-hereditary
- Mean age 13 yo
- Malignant transformation to chondrosarcoma (<5%), by age 40
- Mafucci = enchondromas + vascular calcifications
- Higher rate of malignant transformation (up to 25-50%)
Imaging features and location of juxtacortical chondroma (periosteal chrondromas)
Chondroid tumours arising from periosteum of tubular bones (#1 proximal humerus/distal femur, #2 phalanges)
Soft tissue mass +/- calcification (chondroid matrix), “saucerisation” of bony cortex with periosteal reaction
What percentage of osteochrondromas in HME/diaphyseal aclasia demonstrate malignant transformation to chondrosarcoma? Inheritance pattern? what features are associated with malignant transformation?
Approx. 3-5 % (up to 25%) NB: each lesion has same risk of transformation as solitary osteochondroma AD GLAD-PAST: G: growth after skeletal maturity L: lucency (new) A: additional scintigraphic activity D: destruction (cortical) P: pain after puberty A: and S: soft tissue mass T: thickened cartilage cap >1.5 cm
Features of BPOP? What other entity is in the differential diagnosis?
Bizarre parosteal osteochondromatous proliferations
(AKA Nora lesions)
- Benign, exophytic osteochrondral lesions
- Hands and feet (proximal, middle phalanges)
- Ddx: osteochrondromas - BPOP arises from cortical bone with lack of medullary involvement and does not point away from physis
- Can recur after surgical excision
- On MRI: hypointense on T1-weighted images, hyperintense on T2-weighted images, and uniformly enhancing
Differentiating feature between glomus tumours and intraosseous epidermal inclusion cysts
Location!
- Glomus - subungal hypervascular nodule
- EIC - fingertips (tufts) - usu hx of trauma
Which systemic disease typically manifests as lace-like osteolysis in the hands?
Sarcoidosis
Most common primary malignant bony tumour of the hands?
Chondrosarcoma
Classic epiphyseal lesions (3)
GCT (>20 years), chondroblastoma (<20), infection
Rarely clear cell chondrosarcoma in older patient**
List the polyostotic bone lesions in kids
FEEMHI:
- Fibrous Dysplasia
- Enchondromas (Ollier Disease or Maffucci)
- Eosinophilic Granuloma
- Mets
- HyperPTH (Browns Tumours)
- Infection
Causes of secondary ABCs
Fibrous dysplasia
Chondroblastoma
GCT
Osteosarcoma
Syndrome associated with multiple NOFs
- Jaffe-Campanacci Syndrome (cafe au lait, axillary freckles, and some features of NF 1)
- High risk for pathologic fracture
Conditions associated with polyostotic fibrous dysplasia
McCune-Albright, isolated endocrinopathies, Mazabraud syndrome (fibrous dysplasia + intramuscular myxomas)
Most common primary bone tumours affected the patella
Epiphyseal equivalent
Benign: GCT, Chondroblastoma
Malignant: Mets (#1), lymphoma and hematologic malignancies
Features of Trevor disease
Male**, osteochondroma formation around joints (at epiphysis), or in epiphyseal equivalents including carpal bones, usu ankle and knee, causes pain and malalignment
Most likely causes of aggressive lytic bone lesion in patient over 40
Mets
Myeloma
Lymphoma
Most likely causes of aggressive lytic bone lesion in patient under 20
LCH
Ewings
Infection**
Imaging findings osteopoikilosis
Multiple bone islands + keloid scars
Imaging findings osteopathic striata
Asymptomatic skeletal dysplasia
Linear bands of sclerosis in long bones (fan like in the pelvis)
Osseous findings in Gardner syndrome
- AD Familial polyposis syndrome
- Multiple skull/sinus osteomas, desmoid tumors, fibromatoses
Most common location of osteoid osteoma
Long bones - femur and tibia**
20% occur in the spine (painful scoliosis, will be on CONCAVE side)
DDx. for lytic lesion in posterior elements in young pt
Osteoblastoma or ABC
Could also include GCT (can extend into posterior elements, LCH, and mets)
Least malignant subtype of osteosarcoma
Parosteal sarcoma (90% 5 yr survival)
Differences b/w periosteal and paraosteal osteosarcoma
PARosteal - arises from OUTER periosteum, post distal femur METAPHYSIS most common, cauliflower like exophytic, best prognosis, older (30-40)
PERIosteal - arises from INNER periosteum, DIAPHYSIS of femur or tibia, broad-based soft tissue mass causing erosion/thickening of cortex, aggressive periosteal reaction, may have high T2 signal (predominantly contains chondroid matrix), younger pt (<20 years)
- on MR, may see reactive marrow changes but frank bony invasion is uncommon
- ddx: conventional osteosarcoma (but this usually has medullary invasion, and involves entire circumference)
Most commonly affected joint in synovial osteochondromatosis
Knee (80%) > hip > elbow > shoulder (large joints!)
Differentiating features between primary and secondary synovial osteochondromatosis
Primary: older age, underlying OA, few bodies, variable sizes
Secondary: numerous fragments, similar in size, variable signal intensity on MR
Most common location of enchondromas
Small tubular bones of hands and feet (proximal phalanx most common)
Tubular long bones (femur, tibia, humerus)
Rarely, in pelvis, ribs, scapula - consider chondrosarcoma in these locations!
Features suggestive of chondrosarcoma over enchondroma and risk of transformation
1% risk of transformation in solitary enchondroma
25-30% in multiple enchondromatoses (higher in Maffucci)
- Cortical breech/thickening
- Deep endosteal scalloping
- ST mass
- Pain
- Large size >5 cm
- Permeative/destructive pattern
- Location (much more likely to be a chondrosarcoma outside hands and feet)
- Patient age (older = chondrosarcoma)
Imaging findings chondroblastoma
- Eccentric, epiphyseal, usually around knee or proximal humerus
- Skeletally immature!
- May not see matrix on radiographs, but can on CT
- Unique bc has low to int signal on T2 unlike other chondroid lesions!!
- Lots of surrounding bone and ST edema
Imaging findings chondromyxoid fibroma
- Eccentric, tibial and femoral metaphysis at the knee
- Lobulated lesion, rarely demonstrates chondroid matrix
- Classic sclerotic margin
- Will have high T2 signal on MR
- Usually before age 30
- DDx: ABC, GCT, NOF, chondroblastoma (usually epicentre of this lesion is epiphyseal)
Subtypes of chondrosarcoma and distinguishing features
Conventional (intramedullary, met/diaphysis long bones)
Juxtacortical (surface lesion arises under periosteum, long bones, posterior distal femur most common; ddx: juxtacortical chondroma, periosteal ostesarcoma)
Clear cell (epiphyseal, proximal femur and humerus, well circumscribed sclerotic margination, slow growing, better prognosis; ddx: chondroblastoma)
Myxoid (most common extra-skeletal chondrosarcoma; occur in deep soft tissue most commonly in the thigh)
Mesenchymal (also both intra and extra-skeletal, younger adults than myxoid for soft tissue involvement, has both small round blue cells and cartilaginous component)
Most common adult soft tissue sarcoma
Undifferentiated pleomorphic sarcoma (previously MFH)
Imaging findings in fibrous dysplasia
Lucent lesion, ground glass matrix (sometimes cystic)
Metadiaphyseal, long bones
Also occurs in ribs, pelvis and skull base (ddx: Paget’s - age matters)
Associated with bowing deformity (i.e. Shepherd’s crook)
Risk of fracture
Features of McCune-Albright
Polyostotic fibrous dysplasia, precocious puberty, cafe au lait spots
Features of Mazabraud syndrome
Fibrous dysplasia + intramuscular myxomas
Findings in LCH
Lytic lesion children 5-10 years
Skull: lytic lesion with beveled edge (inner table involved more than outer table)
Mandible/maxilla: bony resorption - floating tooth
Spine: vertebra plana
Long bones: destructive permeative lesion with aggressive periosteal reaction (often lamellated); metadiaphyseal - going to be in ddx with Ewings
Most common paediatric primary bone tumours
1) Osteosarcoma
2) Ewings
Imaging findings in Ewings
Permeative, destructive lesion, large ST component, aggressive periosteal reaction (onion-skin, codmans), sclerosis
Most often in long bones (femur/tib/humerus); 40% flat bones including ribs and scapula
Older age group than LCH - 10-20 years (teenagers)
Almost always metaphyseal or diaphyseal
If outside knee, the consider Ewings over osteosarcoma unless there is clear osteoid matrix
DDx: infection, LCH, mets, osteosarcoma, hematologic malignancy (lymphoma, leukemia)
Most common primary bone tumour in patient over 40
Multiple myeloma
What is POEMS syndrome?
Paraneoplastic syndrome related to plasma cell dyscrasia POLYNEUROPATHY ORGANOMEGALY ENDOCRINOPATHY MONOCLONAL GAMMOPATHY SKIN CHANGES
Associated with SCLEROTIC myeloma
Primary bone lymphoma findings
Long segment of involvement; most often permeative, can be sclerotic
Often has adjacent ST mass
In ddx. for ivory vertebra
Most common location of intraosseous lipoma
Calcaneus, subtrochanteric region of femur, distal tibia/femur, metatarsals
Imaging features of SBC
Usually central, prox diaphysis of humerus or femur (other locations tibia, calcaneus, iliac bone)
Fallen fragment
May have fluid fluid levels
Imaging features ABC
Eccentric, often within the metaphysis of long bones and 20% post elements
Buttressing smooth periosteal reaction
Fluid fluid levels
Causes of lytic metastases
- Lung (most often purely lytic)
- Breast (lytic or blastic)
- Hypervascular tumours (renal, thyroid, etc.)
- Stomach, colon (lytic or blastic)
DDx for fluid fluid levels on MRI
ABC (primary, secondary), GCT, simple bone cyst after fracture, chrondroblastoma, telangiectactic osteosarcoma
Ddx lytic lesion anterior tibial cortex
Adamantinoma - aggressive, intramedullary extension
Osteofibrous dysplasia - less aggressive, may be multiple and have gg matrix
