MSK DDx Flashcards
Long Bone cortically Based Metaphyseal Lesion:
Osteochondroma Non ossifying fibroma / fibroxanthoma Aneurysmal Bone Cyst Insufficiency Fracture Fatigue Fracture Osteoid osteoma Metastasis Fibrous dysplasia Adamantinoma Benign Fibrous Histiocytoma Langerhans Cell Histiocytosis Cortical FIbrous Dysplasia Cortical Chondroma.
Erlenmeyer Flask Deformity:
“Lead HOG”
- Lead poisoning
- Heamoglobinopathy: sickle cell, thalaessaemia
- osteopetrosis.
- Gaucher
“Lead CHONG”
Lead poisoning C: craniometaphyseal dysplasia H: Haemoglobinopathy - Thalaessamia - Sickle Cell Disease O: osteopetrosis N: Niemann pick disease G: Gaucher Disease.
Bone dysplasias
- Osteopetrosis
- Fibrous dysplasia
- Ollier disease
- Multiple hereditary exostoses.
Beak like osteophytes of MC heads with spade like enlargement of terminal tufts:
Acromegaly
MCP Beak like osteophytes:
CPPD (typically 2nd and 3rd)
Haemochromotosis (more joints involved)
Acromegaly (with spade like overgrowths of distal phalanges).
Paediatric cervical spine ankylosis:
Juvenile idiopathic arthritis
Klippel Feil syndrome.
Eitiologies of neuropathic / Charcot Joint:
Diabetes Syringomyelia (upper extremity) Chronic alcohol abuse Amyloid Spinal Tumours Syphilis or Leprosy
Features of Neuropathic Joint: “5 D’s”
Destruction Dislocation Debri Disorganisation no Demineralisation.
Bone features of Sarcoid:
Hands = lace like lytic lesions in middle or distal phalanges.
hands and feet:
- acro-osteolysis
- cyst-like lesions of the phalanges
- hands more commonly affected than the feet
- lace-like osteopenia
Acute or Chronic polyarthritis.
Ankle involvement especially bilateral with erythema nodosum.
Plan: CXR
Bony Sequestrum: “E-FILM”
E: eosinophilic granuloma F: fibrosarcoma I: infection (Brodie abscess) L: lymphoma (skeletal) M: malignant fibrous histiocytoma or metastasis (especially from breast carcinoma)
4 diagnostic features of Giant Cell tumour:
1) Only occur with closed epiphyses
2) Lesion must be epiphyseal / flush with the articular surface.
3) Eccentrically located
4) Sharply defined zone of transition.
GCTs dont have a sclerotic border.
Expansile lytic lesion in posterior elements of spine:
Osteoblastoma
ABC
TB
Epiphyseal Lesion: “Evil AIG Company”
E: epiphyseal: Epiphyseal equivalent bones: - Carpals, - Patella, - Greater trochanter, - Calcaneus.
E: Eosinophilic Granuloma (<30)
A: ABC (expansile) (ABC starts in metaphysis, and can extend into epiphysis once growth plates closed)
I: Infection (closed epiphysis)
G: Giant cell tumour (adult, with closed physeal plates, abutting articular surface)
C: Chondroblastoma (child, eccentric, oedema)
Clear cell chondrosarcoma
Eosinophilic Granuloma (<30yrs).
If over 40: remove ABC / Chondroblastoma / EG, and include Mets and Myeloma.
Automatics for lytic lesion regardless of other features:
Under 30yrs: - Eosinophilic granuloma - Infection Over 40yrs: - Mets - Infection.
Sclerotic lesions:
> 40yrs: Mets.
Lesions that have regressed and become sclerotic: NOF EG Solitary bone cyst ABC Chondroblastoma.
Others: Fibrous dysplasia Osteoid osteom Infection Brown tumour Giant bone island
Malignant bone tumours based on age:
1 - 30yrs: - Ewing - Osteosarcoma 30-40yrs: - Fibrosarcoma - Malignant Fibrous Histiocytoma - Malignant giant cell tumour - Primary lymphoma of bone - parosteal sarcoma > 40yrs: - Mets - Myeloma - Chondrosarcoma.
Diffuse Bony Sclerosis: “3M’S PROOF”
M:Malignancy
- Mets
- Lymphoma
- Leukaemia
M: Myelofibrosis (>50yrs, spleenomegaly, extramedullary haematopoiesis).
M: Mastocytosis (thickened small bowel folds with nodules)
S: Sickle Cell Disease (Bone infarcts, H-vertebrae, splenic autoinfarction)
P: Paget disease
R: Renal osteodystrophy (sub periosteal resorption, Rugger jersey spine)
O: Osteopetrosis (diffusely dense, bone in bone, Sandwhich spine)
O: Other:
- Sclerotic dysplasias: osteopoikilosis, melorheostaosis
- Hyperthyroididm
- Hyperparathyroidism
- Pynknodysostosis (short, hypoplastic mandible, pointed and dense chalk pencil like distal phalanges)
F: Fluorosis (ligamentous calcification).
Shortened 4th or 5th metacarpal:
Pseudo hypoparathyroidism / Pseudo-pseudo hypoparathyroidism.
Turner syndrome
Post traumatic
Post infective
Sickle cell disease with secondary infarction.
Basal cell nevus syndrome.
Paediatric Ivory Vertebrae:
Lymphoma Osteosarcoma Osteoblastoma Blastic Mets: - Neuroblastoma - Medulloblastoma - Ewing Sarcoma
Adult Ivory Vertebrae:
Osteoblastic Mets - Prostate - breast Lymphoma (Paraspinal soft tissue mass) TB Hamangioma Chordoma Paget Disease of spine (expansion of vertebral body)
H shaped vertebrae:
Sickle cell disease
- Associated splenic autoinfarction
Gaucher disease:
- Spleenomegaly.
“THIS” Hair on end appearance skull radiograph:
T: Thalaessaemia
H: Hereditary Spherocytosis
I: Iron deficiency anaemia
S: Sickle Cell disease.
Diffusely Dense Bones algorithm:
Radiographic signs of secondary Hyper-PTH:
- Renal osteodystrophy
Small calcified spleen:
- Sickle Cell disease
Spleenomegaly:
- Myelofibrosis
Predominantly axial skeleton:
- Diffuse osteoblastic Mets
Pathological fractures:
- Osteopetrosis
Others:
- Pyknodysostosis
- Mastocytosis
- Fluorosis
- Athlete.
Expansile or lytic Rib Lesion: “FAMEB:
F: fibrous dysplasia (ground glass)
A: ABC (expansile)
M: Mets / myeloma (soft tissue component)
E: Enchondroma (chondroid matrix) (EG in child)
B: Brown tumour (radiographic signs of secondary hyperPTH).
Causes of AVN:
Trauma Steroids Aspirin Sickle cell disease Collagen vascular disease Alcohol idiopathic
ON MRI assess for background Marrow signal to assess for diffuse symmetrical abnormality as in sickle cell, or just localised to area of AVN.
Bone specific AVN:
Lunate = Kienbock Navicular = Kohler disease Metatarsal head = Freiberg infraction Femoral head child = Perthes Ring apophyses spine = Scheuermann's disease Tibial tubercle = OsGood SLater Disease
Hand arthopathy distribution:
Distal: - Psoriasis - Reactive Arthritis - OA Proximal: - RA - CPPD
High Riding shoulder DDx
CPPD
RA
Torn rotator cuff
SI Joint involvement patterns:
Symmetrical = Symmetrical Letters:
- A: Ankylosing spondylitis
- I: Inflammatory bowel disease
Asymmetric = Asymmmetrical Letters:
- P: Psoriatic
- R: Reactive.
Unilateral: consider infection.
Bilteral SI joint erosions can be seen in hyper parathyroidism as subchondral resorption.
OA / degenerative disease can also cause SI joint erosions.
Vertebral Body Plana DDx: “MELT”
M: Mets / Myeloma
E: Eosinophilic Granuloma (Child)
L: Lymphoma / Leukaemia
T: Trauma / Tb.
Periostitis long bone with / without underlying bone lesion:
Trauma HPOA Venous stasis THyroid acropachy Pachydermoperiostosis
Joints that show erosions in OA:
TMJ
AC-J
SI-J
Symphysis Pubis
Syndesmophytes:
Symmetrical Marginal:
- Ankylosing spondylitis
- Inflammatory Bowel Disease
Asymmetrical Non marginal: (Arising from vertebral body)
- Psoriatic
- Reactive
Vertebral Body Focal T1 Hypointensity:
Basivertebral vein Schmorl node Bone Island Atypical haemangioma Osteomyelitis Mets
Vertebral Body Diffuse T1 hypointensity:
Hyperplastic Marrow (isointense to muscle and discs) Multiple Mets (hypointense to disc) Multiple myeloma (hypointense to disc) Lymphoma (Hypointense to disc) Sick Cell Disease (H shaped vertebrae) Renal Osteodystrophy
Pencil in Cup deformity:
Psoriasis
Scleroderma
RA
Reactive arthritis
Multiple Lytic foci in adult:
FEEMHI
F: fibrous dysplasia E: eosinophilic granuloma (<30) E: enchondroma M: metastatic disease and myeloma/Lymphoma H: hyperparathyroidism (brown tumours) I: infection
Madelung deformity:
Idiopathic Turners syndrome Ollier disease Multiple hereditary exostoses (osteochondromas) Mucopolysaccharidoses Nail-patella syndrome`
"HIT DOC" H: Hurler syndrome I: infection T: trauma D: dyschondrosteosis O: osteochondroma (multiple hereditary exostoses) C: congenital, e.g. Turner syndrome
Lucent metaphyseal bands (child)
Leukaemia Rickets Osteomyelitis Neuroblastoma Mets Scurvy / Vitamin C deficiency Syphillis
Peri articular soft tissue Ca++:
Haemangioma
Scleroderma
Polymyositis / dermatositis (proximal thighs, sheet like)
Myositis Ossificans (intra muscular) Tumoural Calcinosis (idiopathic, cloud like) metastatic Calcification (dialysis / hyper PTH)
Synovial Sarcoma
Chondrosarcoma
Chondrocalcinosis:
CPPD (patello femoral joint)
Hyper PTH
Haemochromotosis (Beaked osteophytes 2 -4)
Wilsons disease
Wormian Bones:
Osteogenesis Imperfecta Cleidocranial dysostosis Trisomy 21 Rickets Hypophosphatasia Hypothyroidism
Multiple Loose Bodies:
Synovial Chondromatosis
PVNS
RA
Posterior element lytic Lesion:
ABC Osteoblastoma Infection / Tb Mets / Myeloma LCH
Vertebral Body Focal T1 Hyperintensity:
Haemangioma
Focal fatty marrow: suppresses on FS or STIR
Pagets
Melanoma Met
Vertebral body Diffuse T1 hyperintensity:
Post radiation
Heterogenous fatty marrow
Chronic Steroid therapy
Paget Disease.
Hip Coxa Terms:
Coxa Profunda: acetabular wall medial to ilioischial line
Acetabular protrusio: femoral head medial to ilioischial line.
Coxa Vara: Flexed femoral neck
Coxa Valga: Straightened femoral neck
Coxa Magna: Asymmetrical circumfrential enlargement and deformation of femoral head and neck.
Acro-Osteolysis DDx (PINCH FO):
P: psoriasis/pyknodysostosis
I: injury, e.g. thermal burn, frost bite
N: neuropathy, e.g. diabetes mellitus, leprosy
C: collagen vascular disease, e.g. scleroderma, Raynaud disease
H: hyperparathyroidism
F: familial, e.g. Hajdu-Cheney syndrome
O: other, e.g. polyvinyl chloride exposure, progeria, sarcoidosis
Band Like Acro Osteolysis:
- polyvinyl chloride (PVC) exposure
- Hajdu-Cheney syndrome
- Hyperparathyroidism (also causes terminal tuft resorption)
- scleroderma (also causes terminal tuft resorption)
- idiopathic non-familial acro-osteolysis
- pyknodysostosis (also causes terminal tuft hypoplasia)
Causes of Sub chondral Cysts:
RA
OA
CPPD
Avascular necrosis.
Epiphyseal overgrowth, gracile diaphyses +/- joint destruction.
Classically associated with widened intercondylar notch:
Juvenile Idiopathic arthritis
Haemophilia
Disuse secondary to paralysis.
Rickets signs: “RICKETS”
R: reaction of the periosteum I: indistinct cortex C: coarse trabeculation K: knees, wrists and ankles mainly E: epiphyseal plates widened and irregular T: tremendous metaphysis S: spur (metaphyseal)
Finger tip lesions: “GEMS”
G: glomus tumor
E: epidermoid/enchondroma/subungual exostosis
M: metastasis (almost exclusively from lung)
S: sarcoidosis
Diaphyseal lesions: “CEMENT”
C: bone cysts E: enchondroma/Ewing sarcoma M: bone metastasis E: eosinophilic granuloma N: non-ossifying fibroma (NOF) T: tuberculosis/osteomyelitis
Wormian Bones: “PORCK CHOPS”
P - pyknodysostosis O - osteogenesis imperfecta R - rickets K - kinky hair syndrome C - cleidocranial dysostosis H - hypothyroidism/hypophosphatasia O - otopalatodigital syndrome P - primary acroosteolysis (Hajdu-Cheney)/pachydermoperiostosis/progeria S - syndrome of Downs
Calcaneal Lesions: “BIG G”
B: bone cyst (unicameral)
I: intraosseous lipoma
G: ganglion (intraosseous)
G: giant cell tumor
Atraumatic pubis symphysis widening: “EPOCH”
E: bladder exstrophy P: prune belly syndrome O: osteogenesis imperfecta C: cleidocranial dysostosis H: hypothyroidism
Gracile Bones: “NIMROD”
N: neurofibromatosis
I: immobilization/paralysis
M: muscular dystrophy, e.g. Duchenne muscular dystrophy
R: rheumatoid arthritis (juvenile RA)
O: osteogenesis imperfecta
D: dysplasia, e.g. Marfan syndrome, homocystinuria
Bone Cortical Lesions: “Fear Of Missing Shit Out”
F: fibrosarcoma O: osteoid osteoma M: metastasis S: stress fracture O: osteomyelitis
Dense Metaphyseal Lines: “PRINCES”
P: poisoning (lead, mercury, antimony, etc.)
R: rickets
I: infection (TORCH); idiopathic hypercalcemia
N: normal variant; neoplastic (leukemia, lymphoma)
C: congenital syphilis
E: endocrine (congenital hypothyroidism)
S: sickle cell disease; scurvy
Growth resumption lines post systemic illness.
Soft tissue calcification: “My GHOSTS”
My: myositis ossificans G: gout H: hyperparathyroidism O: ochronosis S: scleroderma/connective tissue diseases T: tumoral calcinosis S: sarcoma (synovial cell)
Posterior vertebral element lesions: “GO TAPE”
G: giant cell tumor O: osteoblastoma T: tuberculosis A: aneurysmal bone cyst P: Paget disease E: eosinophilic granuloma
Osteolysis distal clavicle: “SHIRT Pocket”
S: scleroderma H: hyperparathyroidism I: infection (osteomyelitis) R: rheumatoid arthritis T: trauma P: progeria
Lucent skull lesions: “MELT ROME”
M: metastasis
E: eosinophilic granuloma
L: lymphoma
T: tuberculosis
R: radiation
O: osteomyelitis
M: multiple myeloma
E: epidermoid
Elbow ossification: CRITOE
C: capitellum (2yrs) R: radial head (4yrs) I: internal epicondyle (6yrs) T: trochlea (8yrs) O: olecranon (10yrs) E: external epicondyle (12yrs)
Permeative Bone process: “FIRE MD”
F: fibrosarcoma I: infection R: round cell tumors (Ewing sarcoma) E: eosinophilic granuloma M: metastases/myeloma/malignant fibrous histiocytoma D: desmoid tumor
Lucent tranverse metaphyseal lines: “LINING”
L: leukemia, lymphoma I: infection (e.g. TORCHS) N: normal variation I: illness (systemic, such as rickets and scurvy) N: neuroblastoma (metastatic) G: growth arrest lines
Multiple Lucent bone lesions: “FEEMHI”
F: fibrous dysplasia E: eosinophilic granuloma E: enchondroma M: metastatic disease and myeloma H: hyperparathyroidism (brown tumors) I: infection
Low signal masses in synovium: “PACS”
P: pigmented villonodular synovitis (PVNS)
A: amyloid
C: chronic bleeding disorders, e.g. hemophilia
S: synovial osteochondromatosis
Focal Sclerotic Bony lesion: “HOME LIFE”
H: healed non-ossifying fibroma (NOF) O: osteoma M: metastasis E: Ewing sarcoma L: lymphoma I: infection or infarct F: fibrous dysplasia E: enchondroma
Cone shaped Epiphysis Causes: ABCDE MOST:
A: achondroplasia, acrodysostosis
B: Beckwith-Wiedemann syndrome
C: chondroplasia punctata, Cockayne syndrome, conorenal syndrome, cleidocranial dysplasia, cartilage-hair hypoplasia
D: dactylitis, Dyggve-Melchior-Clausen syndrome
E: Ellis van Creveld syndrome
M: multiple epiphyseal dysplasia, metabolic (hyperthyroidism)
O: osteomyelitis
S: sickle cell disease
T: thermal injury (burns, frostbite), trichorhinophalangeal syndrome
Fluid fluid level bone lesion: GOATS CSF
G: giant cell tumor
O: osteoblastoma
A: aneurysmal bone cyst
T: telangiectatic osteosarcoma
S: sarcomas
C: chondroblastoma
S: solitary bone cyst
F: fibroxanthoma
Bone lesions without periostitis or pain: E FUN
E: enchondroma
F: fibrous dysplasia
U: unicameral bone cyst
N: non-ossifying fibroma
Lytic bone lesion surrounded by marked sclerosis: BOOST
B: brodie abscess O: osteoblastoma O: osteoid osteoma S: stress fracture T: tuberculosis
Factors favouring Chondrosarcoma over enchondroma:
Pain Cortical destruction Scalloping of > 2/3 cortex > 5cm in size Changing matrix
Arthritis with normal Bone density:
OA Erosive OA Gout Psoriatic arthritis Pyrophosphate arthopathy DISH Haemochromatosis Chronic reactive arthritis PVNS Synovial chondromatosis Robust rheumatoid arthritis.
Arthritis with osteopenia:
Rheumatoid arthritis Bacterial septic arthritis Diabetic charcot arthopathy Ankylosing spondylitis SLE Juvenile idiopathic arthritis Scleroderma Chronic reactive arthritis Haemophillic arthopathy
Arthritis with Productive Changes:
OA Gout CPPD Haemochromatosis Impaction syndromes Ankylosing spondylitis Psoriatic arthritis Osteonecrosis
Erosive Arthritis:
RA Erosive OA Gout Ankylosing spondylitis Psoriatic arthritis Pyrophosphate arthopathy Juvenile idiopathic arthritis Septic arthritis Inflammatory bowel disease arthopathy Reactive arthritis PVNS Synovial chondromatosis
Mixed erosive productive arthopathy:
CPPD Erosive OA Gout Ankylosing spondylitis Psoriatic Arthritis Inflammatory bowel disease arthritis Haemochromotosis
Arthritis with large subchondral cysts:
OA CPPD RA Gout Chronic repetitive traumatic cysts Particle disease PVNS Juvenile idiopathic arthritis Robust RA
Arthritis Mutilans:
RA Psoriatic arthritis Charcot arthopathy Juvenile idiopathic arthritis Gout
MCP joint predominant arthritis:
RA CPPD Haemochromatosis Robust RA Juvenile idiopathic arthritis
Interphalangeal joint predominant arthritis:
OA Psoriatic arthritis erosive OA Chronic reactive arthritis amyloid
Monoarthritis:
Bacterial septic arthritis Post traumatic OA Gout Viral synovitis Neuropathic joint PVNS Synovial chondromatosis Haemophillic arthopathy
Intra articular mass:
Synovial chondromatosis PVNS Joint bodies Cyclops lesion Ganglion, cruciate ligament Displaced meniscal fragments Nodular synovitis RA Lipoma aborescens Intra articular chondroma
Patella Lytic lesion DDx:
subchondral cysts - OA / CPPD
Gout
Chondroblastoma Giant cell tumour Brown tumour PVNS Dorsal defect (mimic) Osteomyelitis
Meniscal Tear Morphology:
Horizontal / Horizontal Oblique:
- Horizontal is parallel to tibial plateau, and in same plane on coronal and Sag
Vertical:
- superior to inferior surface extension
- Curved tear following meniscal contour, remains fixed distance from meniscal edge on Sag.
Bucket Handle:
- Extensive vertical tear
- Absent bow tie sign
- Flipped fragment may be intercondylar notch, anterior displacement causing double delta sign, posterior displacement causing double PCL (medial meniscus).
Radial:
- Vertically orientated tear perpendiclar to meniscal arc.
- Tear changes position relative to meniscal edge on Sag = Marching cleft sign.
- May show Ghost meniscus sign.
Presence / absence of extrusion
Presence / absence of parameniscal cysts.
Osteochondroses Eponymous Names:
- Kohlers:
- Freiberg Infraction:
- Sever’s:
- Panner’s:
- Perthes:
- Kienbock:
- Scheuermann:
- Osgood-Schlatter:
- sinding-Larsen-Johansson:
Osteochondroses Eponymous Names:
- Kohlers: Navicular, boys 4-6
- Freiberg Infraction: 2nd MT head,
- Sever’s: Calcaneal apophysis
- Panner’s: Capitellum, 5-10yrs
- Perthes: femoral head, 4-8yrs
- Kienbock: lunate, -ve ulna variance
- Scheuermann: thoracic spine, 3 levels wedging with kyphosis
- Osgood-Schlatter: tibial tubercle, fragmentation with soft tissue swelling.
- sinding-Larsen-Johansson: inferior patella, adolescents.
Factors favoring chondrosarcoma over enchondroma:
Pain Cortical destruction Scalloping >2/3 cortex >5cm in size Changing matrix
Calcaneal Lesions:
Chondroblastoma:
- epiphysis, usually superior
- Lucent lesion, may have internal Ca++
GCT:
- Metaphysis growing into epiphysis (closed physis)
- Posterior metaphysis / epiphysis usually.
Osteoid osteoma:
- Superior epiphysis
- Sclerotic bone surrounding lucent nidus
Osteomyelitis / Mets:
- favours posterior meta-epiphyseal region.
Solitary Bone Cyst:
- Diaphysis, anterior 1/3 laterally
- Sharp, thick sclerotic edge, multiloculated.
- Fallen fragment sign, T1 dark, T2 bright.
Intra osseous lipoma:
- Diaphysis, anterior 1/3 laterally.
- Fat density CT/MRI
- Central fragment.
Candy stick appearance DDx:
The licked candy stick appearance refers to tapering of the tips of the metacarpal bones, metatarsal bones, phalanges or clavicles and is typically associated with chronic rheumatological conditions:
psoriatic arthropathy
rheumatoid arthritis
leprosy
neuropathic joint
The appearances result from bone resorption/destruction resembling the appearance of a candy stick that has been slowly deformed from licking.
Super Scan Bone scan DDx:
Absent renal bladder uptake
Diffuse Mets: (spares or patchy skull)
- Prostate
- breast
- TCC
Metabolic: (involves diffuse skull/maxilla/mandible)
- Hyper PTH
- osteomalacia
- Myelofibrosis
Poly ostotic periosteal reaction in child:
< 6 months:
- Physiological: symmetrical
- Caffey disease: mandible and clavicles, spares epiphyses.
- Prostaglandin use
- osteomyleitis.
- NAI
> 6 months:
- Juvenile idiopathic arthritis
- Hypervitaminosis A
- Scurvey
- osteomyelitis.
- NAI
Tibial Bowing:
Rickets
Osteogenesis Imperfecta
NF1
achondroplasia