MSK - Bone Tumours Flashcards
What is McCune Albright syndrome?
TRIAD
- Endocrinopathy: Precocious puberty
- Polyostotic fibrous dysplasia
- Cuteneous pigmentation
Variable presentation:
- leg pain and pathological fracture common due to fibrous dysplasia
- abnormal vaginal bleeding
- cushings
-hyperthyroid
Bone Marrow changes from childhood to adulthood
Normal conversion is in this order:
- Long bone Epiphysis
- Long bone diaphysis
- Long bone metaphysis
- Flat bones
- Spine
In marrow REconversion it is the opposite with the spine reconverting first
Proximal femoral metaphysis and distal femoral sparing in TEENAGERS AND mesntrusting women
Marrow conversion
On an MRI scan where you should find high T1 signal fatty yellow marrow there will be low T1 signal red marrow which remains reasonably bright on STIR or other fat saturated sequences. The pattern of marrow reconversion is the exact reverse of the initial conversion, so beginning at the ends of the long bones and spreading to the diaphysis.
In the spine in particular, it can be difficult to differentiate between marrow reconversion and metastases. Even red marrow does contain some fat cells and thus should exhibit some signal drop-out on STIR or out of phase images whereas metastatic disease will not lose any signal at all.
What is a Pitts pit?
Oval lucent lesion seen in femoral neck with sclerotic rim
a DONT TOUCH lesion
Represent herniation of synovium or soft tissues through a cortical defect
What is Osteopoikilosis?
Otherwise known as multiple bone islands
Osteopoikilosis (OPK) is a rare inherited condition of the bones, transmitted as an autosomal dominant trait characterized by numerous hyperostotic areas that tend to localize in periarticular osseous regions.
Once the epiphysis has fused the number remains static
What is Shepherds crook deformity?
Varus deformity of the proximal femur due to fibrous dysplasa (chronic microfractures and remodelling)
Can also appear in: Osteogenesis imperfecta and Pagets disease
What is an Enchondroma?
Wherea are they normally found?
MM (metaphysis, metacarpals)
Cartilage forming tumours
Usually found in the hands (UNUSUAL in terminal phalanges but can be)
Patients typically 10 - 30 years old
-Benign (can transform to chondrosarcoma - think of it if <4cm)
-Should be painless and incidental however can fracture
-Can present within medulla of long bones also
Will be LYTIC in hands and feet
- Will appear as ‘arc and rings’ in femur or humerus*
- Most common are in metaphysis in* skeletally imature
What is a Brodie abscess?
Brodie abscess is osteomyelitis within bone - usually seen in children
-involved metaphysis (if growth plate not fused)
-can involve metaphysis and epiphysis if growth plate fused (vessel traversing across)
On x-ray a lucent lesion with a sclerotic margin should raise the possibility of a Brodie abscess and the presence of a lucent channel extending towards the growth plate is considered pathognomonic.
The diagnosis is usually confirmed with MRI where the sclerotic bone returns little signal on T2 weighted sequences but the adjacent inner granulation tissue returns high signal.
The rim of granulation tissue can enhance with gadolinium but the absence of enhancement does not rule the condition out. Adjacent bone marrow is often oedematous (high on T2, low on T1).
What is an Osteoid osteoma?
What is classic history?
Where do they occur?
What size?
Benign tumors that occur in diaphysis of long bones + posterior elements of the spine
**Adolescent 10 - 25 years old**
-Can cause pain which is classically relieved by Aspirin
Classic history is night pain in a young patient
–differential is Osteoid osteoma OR Osteoblastoma
-if <1.5cm - it is osteoma
-if >2cm it is definitely osteoblastoma (usually seen in older patient still under 30 years though) ***Osteoblastomas can have assc soft tissue component !!!!
Features:
-On CT it will show focally lucent nidus surrounded by sclerotic reactive bone (central sclerotic dot can also be seen)
On MRI there will be ALOT of surrounding oedema
Can be seen in femoral neck
On Bone Scan - double density sign (high signal centrally with low surrounding signal)
What are appearances in Haemophilic arthropathy?
What is a hemophilic pseudotumour?
Knee classically involved
- erosions and subchondral cysts
- widening of intercondylar notch
- epiphyseal overgrowth due to hyperaemia
Haemophilic Pseudotumours
These arise either in soft tissues (usually muscle) or intraosseous
Can cause adjacent scalloping. Blood degradation products present
Will have peripheral rim of low signal haemosiderin
What is Lipoma aborescens?
Affects children and adults
Most commonly in over 50’s with recurrent effusions
Affects synovium with fatty deposition within it
- gives ‘frond like’ fatty deposition in synovium
- can have effusion
Plain film will only show an effusion
Tx: Synovectomy
What is Mortons Neuroma?
Due to fibrosis surrounding a plantar digital nerve
Usually in 3rd web space slightly proximal to metacarpal heads
US: hypoechoic
MRI: low on T1, T2 and STIR
DOES enhance however
Differential is intermetatarsal bursitis which extends above the plantar ligament (mortons doesn’t)
Intermetatarsal bursitis appears dumbell shaped
Features of an intraosseous lipoma?
Well defined lucent lesion on plain film
Calcification at the centre of it pathonomonic
Faint sclerotic rim
Fat denisty on MRI or CT
What is a geode?
A subchondral cyst communication with the joint
Seen in older patients with OA
What is unicameral bone cyst?
How to differentaite from IO lipoma?
Simple bone cyst
- Proximal Humerus*
- Proximal femur*
Has well defined sclerotic border
***Metaphyseal
***Can have fallen fragment sign
Seen in children
Can be multiloculated
WONT have central calcification (differentiator from lipoma)
What is Tumoural calcinosis?
Typically seen in Black patients in their teens or 20’s
Inherited condition where there is accumulation of hydroxyapatite fluid in joints
UNDERLYING BONES ARE NORMAL
-Appears as calcified soft tissue mass on imaging
-Overlying skin can ulcerate giving chalky milk fluid
What is Erdheim chester disease?
What does it cause?
50 year old presenting with Bone pain
Due to overproduction of Histiocytes (similar but different to LCH. this is a non-langerhan cell disorder)
Peaks around 55 years of age
Present with Triad:
1. Bone pain
2. Exopthalmos
3. Diabetes insipidus
***Plain film: Bilateral symmetric sclerosis in metaphyseal and diaphyseal regions***
- Cortical thickening*
- Increased uptake on bone scan*
Can also have cystic lung disease and retroperitoneal fibrosis
Histocytes are immune cells comprised of macrophages, monocytes and dendritic cells
Giant Cell tumours
Where do they most commonly occur?
Most common at age 20-30 years
Physis must be closed
Can cause pain and can cause mass effect
**Lucent lesion that occurs in the epiphysis
**Cause cortical expansion
**Eccentric in location (edge)
**Well defined margin (NO sclerosis)
Most common in the knee (distal femur) or Proximal Tibia
Can also occur in spine (mostly thoracic) and cause compression of nerves
T1: Low
T2: heterogenous high with areas of low T1 due to haemosiderin
Differential is ABC (theyre usually in children but can occur at any age)
What is an Osteochondroma?
Where is typical location?
Benign or malignant
Benign lesion with small risk of malignant transformation
- Develop during childhood but once present are there for rest of patients life*
- Most cases are in lower limb*
Can form as a result of radiation
Bony exostoses pointing away from joint
Cartilaginous cap
Can have differing appearances and can be multiple (Trevors disease)
Note supracondylar avian spur in the humerus is a normal variant (will point TOWARDS the joint. Can compress the median nerve)
Finger (phalanx) lesion in a child with chondroid matrix
What is it?
Juxtacortical (Periosteal) chondroma
Rare tumour
Ring and arc calcifications
DO NOT TOUCH LESION
Small lucent lesion at distal femoral metaphysis
‘Irregular but intact cortex’
‘Scoop like defect’
Cortical Desmoid
Completely benign
Don’t need MRI either
Common areas for calcific tendonitis - calcium hydroxyapatite
Shoulder
Longus coli muscle - anterior to C1, C2, C3 vertebral bodies (prevertebral region)
Patients can present with acute neck pain, fever, dysphagia
Thalassaemia and bony issues
What are they?
3
- Extramedullary haematopoeisis
- Hair on end appearance of skull
- Expansion of ribs and facial bones
- Hypertelorism and reduced pneumatisation of sinuses
Milwaukee shoulder
What is it?
Who does it occur in?
Occurs in old ladies
Massive destruction of the humeral head due to deposition of hydroxyapatite crystals
- -joint effusion*
- -superior subluxation of the humeral head*
- -subchondral sclerosis*
- -intra-articular loose bodies*
Approach to decided type of arthropathy
