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Radiology Facts


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Congenital Heart Disease
1. Acyanotic & inc Pulm flow: ASD, VSD, PDA, ECD (Down's)
2. Acyanotic & nl/dec pulm flow: AS, Ao coarctation, Pulm Stenosis
3. Cyanotic & inc Pulm flow: TGA (common), Truncus, TAPVC, Tri atresia, Tingle ventricle
4. Cyanotic & nl/dec Pulm flow: Tetrallogy, Ebstein, Tri atresia, Pulm atresia
DDx of "Honeycombing" on HRCT
Scleroderma/ RA
Chronic hypersensitivity pneumonitis
Drug/Toxin (e.g., Bleomycin)
DDx of " Tree in Bud" appearance on HRCT
Asian panbronchiolitis
Viral PNA
Lymphangitis carcinomatosis
DDx of endobronchial mass
Tumors: SCC, Adenoid cystic, Mucoepidermoid, Oat cell, Carcinoid, Mets (RCC, melanoma, breast, colon thyroid)
Mucous plug
DDx of Bronchiectasis
1. Post infectious: TB, aspiration, ABPA (central), pertusis, radiation

2. Bronchial obstr: Neoplasm, F.B.

3. Congenital: CF, Bronchial cartilage def., Kartagener's
DDx of "Pleural based mass"
Fibrous tumor of the pleura
Malignant Thymoma
Mets (Breast, lung, prost, thyr, RCC)
Extrapleural tumors
DDx of "Calcified pleural plaques"
Fluid (empyema/hemotx --> fibrothorax)
Anterior mediastinal mass
1. Thymus: cyst, thymolipoma, thymoma (common), CA, thymic carcinoid, lymphoma
2. Teratoma / germ cell tumors (Embyonal cell, seminoma, choriocarcinoma)
3. T-cell lymphoma
4. Thyroid lesions
DDx of superior mediastinal mass
Thyroid CA
Adenopathy (Head & neck CA)
Lyhpatic cyst / cystic hygroma
Oat cell CA
DDx of middle mediastinal mass
1. Adenopathy: sarcoid, TB, fungal, beryllium, neoplasm, lymphoma
2. Congenital: Bronchogenic cyst (subcarinal/pretracheal), pericardial cyst
3. Aneurysm
4. Esophageal: Hiatal hernia, esoph divertic or CA, achalasia, hematoma, vx
DDx of hilar adenopathy
1. Low attenuation: TB, fungal, AIDs, mets, lymphoma
2. Enhancing: Castleman's (giant benign nodal hyperplasia, vasculat mets (RCC, thyroid, oat cell, melanoma)
3. Calcified: TB, Histo, fungus, sarcoid, silicosis, post XRT
DDx of posterior mediastinal mass
1. Neurogenic (90%): schwanoma, neurofibroma (45%), ganglioneuroma, neuroblastoma, pheo, paraganglionoma, lateral meningomyeolocele
2. T-spine: EMH, hematoma, neoplasm
3. Aneurysm
DDx of densely enhancing mediastinal mass
1. Vascular: aneurysm, AVM, esoph vx
2. Tumor: paraganglioma, vascular met (RCC, thyroid)
3. Goiter
4. Castleman's dz
DDx of Hilar LN eggshell calcification
Treated lymphoma
Histoplasmosis (more commonly diffuse ca+)
Sarcoid (rare and late)
DDx of pulmonary artery ectasia
Pirmary pulm HTN (rare, young, female)
Secondary pulm HTN (COPD)
PA stenosis
AVM (Osler Webber Rendu)
Conditions Associated with Right Aortic Arch
Truncus arteriosus (35%)
Tetralogy (30%)
Tricuspid atresia
DDx of rib notching
1. Superior: HyperPTH (common), idiopathic, polio, RA, SLE, local pressure, osteogenesis imperfecta, Marfans
2. Inferior: Coarctation, Blalock Taussig shunt, Takayasu's (unilat), SVC obstruction, AVM, Intercostal neuroma
Associated findings in Down's syndrome
Hypersegmented manubrium
11 pairs of ribs
Findings in acute cholecystitis
Sonographic murphy's (most specific)
Visualized gallstones
GB wall thickening > 3mm
Pericholecystic fluid
DDx of scoliosis
1. Idiopathic 70%
2. Congenital: hemivert, butterfly vert
4. other: NF, CP, muscular dystrophy, myelomenigocele, polio, spinomuscular atrophy, paralytic scoliosis 2/2 cord injury

All have increased COBB ANGLE.
Adrenal myelolipoma
Adrenal hamartoma with erythroid, myeloid, and fatty elements. Fat content (<0 HU) is virtually diagnostic and often distiguishes this entity from adrenal adenomas.
A nonfunctioning adrenal adenoma discovered serendipitously. These occur in 8% of the population and are more common in older, fat diabetic, hypertensive patients (sydrome X). Must be d/dx from met in pts with h/o malignancy --> look for presence of fat to avoid Bx if possible (<10 HU).
DDx of Cushings Syndrome
Cushing's Dz (#1 cause): pituitary adenoma --> smooth bilateral nodular thickening
Adrenal adenoma: focal low density round mass with normal or atrophic contralateral gland
Adrenal carcinoma: large with central necrosis and irregular margins. 30% calcify
Ectopic ACTH: oat cell CA of lung
Malignant tumor of adrenal gland or sympathetic ganglion. Aggressive cousin of pheo. Occure in children. Large lobular with stippled calcification. T2 bright. Presence of bone mets indicated poor Px.
Malignant neoplasm of adrenal medulla. Present w/ paroxsymal HA, diaphoresism pals, and HTN. Ruel of 10's: 10% bilat, extraadrenal, malig, familial (MEN II)
Extraadrenal locations: sympathetic chain, Zuckerkandl).
Well circumscribed > 3cm
Very bright on T2 (light bulb lesion)
Renal Cell CA
Malignant tumor of distal tubules. Highly vascular with tendancy towards bleeding. May have cystic components that resemble simple renal cyst. Often metastasizes to lungs and bone (lytic). Stage III (renal vein/IVC), stage IV (distal mets or local invasion). Most are sporadic, but risk factors are VHL and chronic HD. Major DDx is w/ Oncocytoma - benign renal tumor with same imaging characteristics except that most are hypovascular and hve spoke wheel appearance.
Middle eastern patient
Hematuria and bladder mass --> SCC
Bladder wall calcification
Benign solitary renal mass.
Middle aged female.
Mixture of smooth muscle, fat, and vessels.
Presence of fat (<0 HU) is diagnostic.
Usually asymptomatic, but can enlarge.
May be multiple and bilateral in patients with tuberous sclerosis (skin lesion, low IQ, and multiple hamartomas).
Adult Polycystic Kidney Dz.
Autosomal dominant.
Large polycystic nonfunctioning kidneys
Pancreatic and hepatic cysts
15% have intracranial aneurysms (check MRA).
DDX of Medullary nephrocalcinosis
1. HyperPTH
2. Medullary sponge kidney: asymp dilation of collecting tubules in renal medulla. can have stones/infxn (bouquet of flowers on IVP), ass'd with Caroli's dz and hepatic fibrosis.
3. RTA
Intracerebral Hematoma
Traumatic brain injury (i.e. cortical contusion)
HTN (BG and pons)
AVM (supratentorial)
Amyloidosis (GW jxn of occip and parietal)
Mets from RCC or Melanoma
GBM or other primary CNS tumor
Subdural hematoma
Elderly after head trauma
Shearing of bridging veins
Crescentic extraaxial blood collection
crosses suture lines, but respects dural reflections (falx, tentorium)
Acute --> high attenuation
Chronic --> low attenuation
Eosinophilic Granuloma/ Langerhans Histiocytosis
Multiple cysts and nodule with upper lobe predominance and peribronchovascular distribution.
Occurs in young smokers.
Nodules-->cavitary nodule --> interstitial fibrosis with cysts (late)
Pts may present with recurrent spontaneous PTX
CXR show normal lung volumes with sparing of CPA
Tx is to stop smoking
Px is variable with 1/3 progressing to ESLD
Pulmonary Alveolar Proteinosis
Accumulation of PAS+ material in distal airspaces with little underlying inflamation.
30-50 yr, M>F
Progressive SOB, nonproductive cough
Opportunistic infxn with nocardia/TB/fungi 2/2 macrophage dysfunction.
CXR shows large bilateral symmetric central/lower lung zone opacity (i.e. Batwing)
HRCT shows GG opacity with thickening of interlobular septa ("crazy paving")
Tx with pulm levage if symptomatic. Steroids no helpfull.
Excessive prolif of granulation tissue in small airways.
50-60 yrs, M>F
S/Sx suggestive of CAP
CXR with bilateral diffuse / pathcy alveolar infiltrate with normal lung volumes. Recurrent / migratory opacity.
HRCT with patch ASD, GG opacity, bronchial wall thickening
Tx with steroids
Px is usually good.
Benign polyclonal prolif of B cells in lungs
mono/polyclonal gamopathy on SPEP
50's, F>M
Progressive cough x several month
--> honeycombing (late)
Variable Px (1/3,...)
50-60's M>F
Progressive SOB and cough
CXR with diff interstitial opacity and decr lung volumes
HRCT with subpleural and basilar opacity (reticulonodular)--> honeycombing with traction bronchiectasis (late).
Px is poor with progression to ESLD and death in 5-10 yrs.
Etiology likely 2/2 abnormally increased fibrogenesis rather than inflamation.
Exclusively in smokers
Alveolar spaces filled with macropages (smokers histiocytes) rather than desquamated pneumocytes)
HRCT with patchy peripheral GG opacity and some cystic changes.
Tx steroids.
Px is good. > 10 years mean survival.
Respiratory bronchiloitis
Like DIP
BUT smokers histicytes fill respiratory bronchioles instead of alveoli.
Good Px.
AIP / Hammon Rich Syndrome
Explosive onset and progressive course.
Poor Px - like ARDS
Extensive interstitial fibroblast proliferation
No clear insiting event.
Uniform cellular infiltrate with varriable degrees of fibrosis
Subacute onset
HRCT with GG opacity and consolidation
Better Px than UIP.
Thin walled cysts with normal intervening lung.
Females of childbearing age.
Presents with SOB and spontaneous PTX
Chylous pleural effusions offten seen.
Parotid gland tumors
1. Benign (80%): Pleomorphic adenoma, Warthin's tumor
2. Malignant (20%): Adenocarcinoma, Adenocystic, Squamous cell, Mucoepidermoid
Thyroid Tumors
1. Benign: Thyroid adenoma

2. Malignant: Follicilar, Papillary, Anaplastic Carcinomas

Risk factor is h/o prior radiation exposure.
Epidural hematoma
Extraaxial blood collection
Lenticular shaped
Crosses dural reflections, but respects suture lines
95% are associated with overlying skull fx.
Often 2/2 laceration of middle meningeal artery.
DDx of middle ear soft tissue mass
Chronic OM
Granulation tissue
Cholesterol granuloma
Glomus tympanicum tumor
DDx of Jugular fossa mass
Glomus jugular tumor (#1, highly vascular)
Neurofibroma (#2)
DDx of tram track enhancement of ooptic nerve
Optic nerve meningioma
Optic neuritis
Normal varriant
DDx of orbital mass
1. Adult: Hemangioma, schwannoma, melanoma, menigioma, lymphoma, peudotumor (painful proptosis, occular muscle enlargement, steroid responsive), carotid-cavernous fistula, mucocele
2. Kids: Retinoblastoma, Rhabdomyosacr, optic nerve glioma, lymphoma, hemangioma, dermoid cyst, neuroblastoma
DDx of cystic neck mass
Thyroid: colloid cyst, cystic degeneration, papillary CA, cystic mets

Extrathyroid: Branchial cleft cyst (lateral to carotid), thyroglossal duct cyst (midline mass), Ranula (retention cyst of sublingual gland), Cystic hygroma (kids)
DDx of Solid Neck mass
Parotid tumors
TB (scrofula)
Ectopic thyoid
DDx of extraxial mass
1. Hemispheric: Menignioma, mets, lymphoma, arachnoid cyst, dermoid/epidermoid, ICH
2. CPA: acoustic neuroman, facial neuroma, meningioma, epidermoid, paraganglioma, petrous apex cholest. cyst, aneurysm, mets
3. Clivus/prepontine cystern: mets, menignioma, chordoma, chondroma, chondrosarcoma
DDx of Inraaxial mass
1. Hemespheric: Astrocytoma, GBM, oligodendroglioma, lymphoma, met, PNET, ganglioma, gangliocytoma
2. Sella: Adenoma, craniopharyngeoma, rathke's cleft cyst, met, abcess, sarcoid, EG stalk
3. Pineal: Germ cell tumor, pineal parenchymal cell
4. Cerebellum: Astrocytoma, meduloblastoma, hemangioblastoma, met, ependymoma, chorid plexus papilloma/CA
5. Brainstem: astrocytoma, GBM
DDx of suprasellar mass
Pituitary microadenoma (#1 for adults)
Craniopharyngeoma (#1 for kids)
Sarcoid - sellar lesion with SS extension
Arachnoid cyst
Germ cell tumors
Hypothalamic glioma
Optic glioma
DDx of ring enhancing lesion
Brain abcess
Brain met
CNS lymphoma
Cysticercosis (look for scolex)
primary CNS tumor (glioma)
DDx of Basal Ganglion Ca++
Physiologic (#1)
Post inflammatory (TB, Toxo)
Danny Walker MAlformation
1. Vermian hypoplasia/aplasia
2. Large psterior fossa

Must be d/dx from mega cisterna magna and Chiari IV (complete abcess of cerebellum)
Cystic space within spinal cord secondary to dilation of central canal.
Must r/o Chiari malformation, spinal dysraphism, DW malformation, diastematomyelia, astrocytoma, ependymoma and trauma..
80% of gliomas
Hemispheric in adults
Brainstem (pilocytic) in kids
Low grade I->II->Anaplastic (III)-_ GBM (IV)
Multicentric glioma must be DDx from mets
Tectal gliomas have good Px - no need for Bx, just follow.
Uncommon primary CNS tumor of adults.
Slow growing
Present as large hemispheric mass (usually frontal lobes).
Hypodense with cysts
805 have calcification
Can cause pressure erosion on skull.
Ependymal tumors
Ependymoma: slow growing into 4th ventricle. Children, NF2, extrudes through Luschka into CPA and CM which helpos ddx from mebulloblastoma. 50% have fine calcification and or cystic regions.
Subependymoma: Asymptomatic 4th ventricle tumor seen in elderly males. often multiple.
Choroid plexus papilloma/ carcinoma
Rare tumor or lateral ventricles.
Age < 5yr.
90% benign papilloma
Can occur in 4th ventricle or CPA in adults
Often with drop mets to spinal canal
Strongly enhancing.
25% calcify
Cell of origin is the arachnoid cap cell.
F>M, age 40-60 yr.
20% of all CNS tumors
90% supratentorial
Extraaxial, strongly enhanging (key feature)
20% calcify
Dural tail, slow growth, round shape
Spoke wheel appearance on angio with persistent tumor blush
Similar MR signal as falx (T2 dark, with strong enhancement).
Benign neoplasm of endotherlial cell origin.
Most common primary cerebellar tumor in adults with VHL.
Characteristically is cystic lesion with enhancing mural (pial) nodule (80%)
Benign tumor of kids and adolescents
Contains glial and neural elements
Slow growing
Pt presents with seizures.
Cortical lesion of temporal lobes
Suspect if in young patients with long h/o sz s/o and temporal lobe cortical mass.
Aggressive infratentorial PNET of children
Roof of 4th ventricle (midline cerebellar)
Associated with Turcot's syndrome
Intense homogenoues enhancement (key feature)
Dense cell packing (hyperintese on noncontrast CT).
Nerve sheath tumor (benign)
Associated with NF2
90% are in CPA from VIII
CPA mass, > 2 mm diff b/w R and L IAC, IAC > 8mm
Icecream cone appearance
T2 bright, enhancing
Pineal Tumors
Kids and adolescents
Parinauds syndrome (no upward gaze)/hydrocephalus
Germ cell tumors (>50%): Germinoma (#1 like seminoma), teratoma, embryonal cell (+HCG+AFP), choricoCA (+HCG-AFP), yolk sac tumor (-HCG,+AFP)
Pineal cell tumors (25%): Pineocytoma (beign), Pinealoblastoma (malignant PNET in pts with Rb, exploded calcification).
CNS lymphoma
B cell NHL
Located deep (BG and periventricular WM)
2 lymphoma --> leptomeningeal eeding
Diffusely infiltrative with little mass effect
Dense cell packing
Ring or homogenous enhancement
Elevated Choline peak on MRSI
May resolve with short course of steroids.
DDx from Toxo (multiple cortical lesions with increased lipid/lactate on MRSI).
Arachnoid cyst
Arises from splitting of arachnoid membrane.
75% are in kids
Middel cranial fossa, SS and quadrageminal cistern, CPA and CM
Extraaxial mass with CSF signal. Can cause mass effec and pressure erosion of skull by slow enlargment.
Colloid cyst of 3rd ventricle
Interventricular foramen of Monro
Intermittent HA, ataxia from obstructive hydrocephalus
T2 hypointense (incr paramagnetic content)
CT hyperintense
Arthritis 2/2 urici acid crystals
Risk factors are uric acid
1. overproduction: EtOH, ChemoTx, lymphoma, Liesch Nihan Synd, or
2. underexcretion: HCTZ, renal failure, EtOH, hyper or hypoPTH
LE>UE, small>large joints
Marginal erosions
Overhanging edges
Preserved joint space
Juxtaarticular ST deposits (tophi)
olecranon bursitis
Carcinoid tumor
Most common benign 1 lung tumor
Central mass (often with endobronchial component) or peripheral nodule.
Occasionally with benign appearing calcifications
Rarely have carcinoid syndrome (flushing, tachy, hypotesion, wheezing, secretory diarrhea, tricuspid valve abnl).
Bilateral symmetric perihilar opacities
Bilateral upper lobe cysts 2/2 prior prophylaxis with aerosolized pentamidine.
DDx of consolidation
Neoplasm (bronchioalveolar)
Pulmonary contusion/hemorrage
Alveolar proteinosis
Lipoid Pneumonia
Pulmonary edema
DDx of posterio mediastinal mass
1. Neurogenic: schwanoma, NF, ganglioneuroma (fusiform with vertically oriented long axis)
2. T-spine fx with paraspinal hematoma
3. EMH in pts with hemolytic anemias
IV contrast premedication
Prednisone 50mg PO 13h, 7h,1h prior
Benadryl 50 mg PO 1h prior

Incidence of contrast rxn 5-12% HOCM, 1-3% LOCM

Acute Tx: Epi 1:1,000 0.1-0.3 ml SC q15min x3 --> 1:10,000 1-3 ml IV
T1 wieghted image
Low TE = 20 ms
Low TR = 600 ms
Fat is high signal
Water is low signal
Subacute blood (methemaglobin), pus, melanin, gadolinium are all high signal.
T2 weighted image
High TE = 80 ms
High TR = 3000 ms
Water/ fluid is high signal
Calcium, gas, old blood (hemosiderin), fibrous tissue are all low signal
Proton density
Low TE = 20 ms
High TR = 3000 ms
Combined T1 and T2 properties
Pleural effusion
PA view detects > 200 cc fluid
Decubitus films can detect less fluid
Trasudate: Pleural/Serum protein <0.5, Pleural/Serum LDH<0.6, Pleural LDH < 200
Subpulmonic effusion: hard to Dx as there is no blunting of CPA. Look for lack of visible bronchovascular structure behind hemidiaphram
Pulmonary Hamartoma
Well circumscribed
Pulmonary nodule
Popcorn calcification often present
+ fat on CT
Acute appendicitis
U/S findings: Diameter>6mm, noncompressible
CT findings: >6mm, enhancing wall, appendicolith, fat stranding cecal effacement, periapendiceal fluid, lack of filling, abcess
10-20% risk if diverticulosis is present.
CT findings: colonic wall thickening, diverticulae, abcess, fat stranding, localized extraluminal or free intraperitoneal air.
Must be DDx from colonic CA that has perforated.
Arthropathy similar to OA
Knee (petelofemoral)
Associated with hyperPTH, Gout, Hemachromatosis
Pigmented Villonodular Synovitis
Adults with synovial hypertrophy and hemosiderin deposits
Diffuse or focal
Errosive (large cystic cavities)
Joint space narrowing late
Bone tumor matrix
Osteoid: OO, osteoblastoma, osteochondroma, bone island, osteosarcoma
Chondroid: Enchondroma, osteochondroma, chrondroblastoma, chondromyxoid fibroma, chondrocsarcoma
Intermed: Fibrous dysplasia, osteoblastoma, osteosarc
Cellular: Fibrous tumors, round cell tumors
Osteoid osteoma
Clinical hallmark is noctural pain relieved by ASA
Young males
Tx percutaneous RF ablation
intracortical lesion with lucent nidus < 2cm
Limb overgrowth in kids
Sclerotic rim surround nidus
Hot on bone scan
Histologically like osteoid osteoma
Less common
Rapid expansile lytic growth well circumscribed (like ABC)
Varriable sclerosis (>2cm with sclerosis is giant osteoid osteoma)
Spine and long bones
If malignant, can have ST component like osteocarcoma
2nd most common primary bone tumor (after MM)
Long bones (femur, tib, humerus)
ill-defined, intramedullary, with s.t. mass
Marked periosteal reaction (codman, sunburst)
Telangiectatic varriant has no matric or periosteal rxn but is more malignant (lytic) and can mimic and ABC.
Benign centrally located (medullary) cartilagenous tumor
Predilection for phalanges
Usually asymptomatic but can have path fx
Lytic with rings and arcs calcification
Endosteal scalloping and cortical expasion
No ST mass of periosteal rxn
Can rarely undergo malignant transformation
Oillers dz (enchondromatosis) = multiple unilateral enchondromas of hands and feet that stabilized at puberty, inc risk of chondrosarc.
Maffucci's synd = Oiller's dz & multiple S.T. hemagiomas.
Cartilage cpped benign bony projection from metaphysis.
Has growth plate which fuses at puberty
Always grows away from joint
Painless. M>F
MOCE = auto dominant, sessile lesions, severe growth abnl, and rarely malignant transformation.
Chondromyxoid fibroma
Rare benign tumor
Geographic, lytic appearance, eccentric location about knee
Cartilagenous matrix rarely seen
Tx req curettage
Malignant cartillagenous tumor
Usually low grade, asymptomatic, incidentally found
Usually metaphyseal
Lytic +/- chondroid matirx
Medullary or exostotic
Can degenerate into fibosarcoma, MFH, or OSA in 10%
Rare benign tumor
Exclusively found in epiphysis of immature skeleton
Knee or proximal humerus
Tx is currettage
Fibrous Cortical Defect
Cortically based lesion of whorled conective tissue bundles
Histologically identical to NOF
No medullary involvement (unlike NOF)
1-4 cm (smaller than NOF)
Asymptomatic (no risk for Fx)
Lucent cortical lesion with nl or sclerotic border.
90% are in tib/Fib metaphyseal location
Nonossifying fibroma
Histologically same as FCD
Larger tha FCD (1-7cm)
May cause pain if path Fx (Tx with currettage if symptomatic)
Involves medulla
Metaphyseal location (90%) Tib/Fib
Unicameral Bone Cyst
Benign centrally located, commmon
Fluid filled lesion
Kids 10-20 yr
Usually present with path Fx and pain
Long bones (prox humerus or femur)
Does not cross physis
Expansile (fluid/fluid levels)
Fallen fragment sign 2/2 path fx is pathognomonic!
No periosteal reaction
Resolves with puberty
Aneurysmal Bone Cyst
Expansile thin walled blood filled cystic cavity
Rapid progression (2-6 mo) with increasing pain
Eccentric location
Posterio spine, long bone metaphyses, Pelvis
No periosteal reaction
Fluid/fluid levels
DDx of peripheral artery aneurysm
Inectious/Mycotic - staph, syphilis, salmonella
Inflamatory - Takayasu (pulseless dz), GCA, PAN
Congenital - Marfan, honocysteinuria, Ehlers-Danlos
Fibromuscular dysplasia
Pseudoxanthoma elasticum
Contrast induced nephrotoxicity
Persistent nephrogram >24-48h
Vicarious ecretion of contrast wia liver/biliary (e.g. galbladder opacification)
Dermatomyositis arthropathy
Widespread S.T. Calcification is hallmark finding.
SLE arthropathy
Distribution like RA (symmetric)
Prominent subluxation of MCP joints (reducible)
S.T. swelling
Rheumatoid Arthiis
Clinical Dx (7/11 classic, 5/11 definite, 3/11 probable).
Am stiff, pain, swelling>1 joint, symetric swelling, SQ nodules, Xray changes, +RF>1:64, poor mucin clot of synovial fluid, hystology.
Hands & feet most effected
Symmetric ST swelling and joint space narrowing, marginal errosions, periarticular osteopenia, subchondral cysts, errosion of ulnar styloid, triquetrum, and dense with AA dislocation.
Felty's = RA, splenomegally, neutropenia and thrombocytopenia
Caplan's= RA, peumoconiosis, Rheumatoid lung nodules
Scleroderma Arthropathy
S.T. calcification
Acroostolysis (2 resorption)
Erosive changes of DIP and PIP
Inflamatory arthropathies
Autoimmune: RA, SLE, Scleroderma, Dermatomyositis
Seronegative: AS, Reiter's, Psoriatic, Enteropathic (UC, chrons, whipples, SSY)
Erosive OA
Arthritis: General Approach to Dx
Alignment - sublux, ulnar dev, disloc (RA, SLE)
Bone - osteoporosis (RA), Erosions (RA, psoriasis), New bone (ostephytes, ankylosis, periosteal)
Cartilage - joint space narrowing
Distribution - prox (RA, CPPD, AS)v. distal (Peiters, psoriatic), Mono v. Polyarticular
S.T. swelling
Metabolic arthopathies
Crystals: Gout, CPPD, Basic calcium phos
Endocrine: Acromegally
Other deposits: Hemochromatosis, Willsons, Alkaptonuria, Amyloidosis, Xanthomatosis, Multicentric reticulohistiocytosis
Gradient Echo
Low TE = 20 ms
Low TR = 600 ms
Blood vessels appear bright
Fluid is bright
Reiter's syndrome
LE distribution: MTP>calcaneous>ankle>knee
M>F, HLA B27
Follows nongonoccocal urethritis or dysentery (SSYCE)
MET errosion
Enthesopathy (achiles tendon and plantar aponeurosis)
Bilateral sacroiliitis (asymetric initially)
Bulky asymmetric thoracolumbar bridging osteophytes.
Psoriatic arthritis
Seronegative spondyloarthropathy
Upper ext polyarticular asym oligoarth)
90% have skin changes, the severity of which correlates with joint dz.
50% have HLA B27
SI joint and spine similar to Reiter's
Erosions: pencil in cup, terminal tuft resorption
ST swelling: Sausage digits
New bone: Mouse ears, ivory phalanx
Ankylosing Spndylitis
Affects axial skeleton and large prox joints
onset in 20s
HLA B27 related
Associated with IBD, iritis, aortitis, and upper lobe pulm fibrosis
Bilateral symetic SI joint erosion->sclerosi->ankylosis
Enthesopathy od tuberosities
Bamboo spine
Ligamentous ossification and Syndesmophytes = calcified outter anulus fibrosus
Clay Shoveler's Fracture
Avulsion of lower c-spine spinous process (usually C7).
Mechanism of injury is powerful hyperflexion (e.g., shoveling).
Obtain swimer's view if needed to see C6-7.
Chance Fracture
Lap-type seat belt fracture L2-L3 secondary to hyperflexion and distraction injury.
Horizontal split vertebral body with rupture of posterior ligamnets.
>50% association with small bowel / colon injury (seat belt syndrome).
Galeazzi Fracture
1. Distal radial shaft fracture &
2. Distal radioulnar dislocation.
Essex-Lopresti Fracture
1. Comminuted radial head fracture &
2. Distal radioulnar subluxation/ dislocation.
Colles' Fracture
Extraarticular fracture of distal radius.
Dorsal displacement and angulation.
2/2 FOOSH injury
May be impacted with limb foreshortening.
Ulnar styloid fracture found in 50%.
Pts often have median or ulnar nerve injury.
Smith's Fracture
Distal radius fracture
Volar displacement and angulation of distal fragment.
Type 1: Hoizontal fx line
Type 2: Oblique fx line
Type 3: Intraarticular fx (A.K.A. Reverse Barton's)
Barton's Fracture
Unstable intraarticular fracture of dorsal margin of distal radius.
Carpus follows distal fragment.
Requires ORIF.
Monteggia Fracture
Ulnar shaft fracture with radial head dislocation.
Chauffeur's fracture
Intraarticular fracture of the radial styloid.
Rolando Fracture
Comminuted intraarticular fracture of 1st MCP joint at the base of the thumb.
Three patterns: Y-, V-, T-shaped fxs.
Radial & dorsal dislocation 2/2 pull of APL.
Bennett's Fracture
Intraarticular fracture at the base of the 1st metacarpal involving the 1st MCP joint.
Dorsal and radial dislocation 2/2 APL
Small fragment articulates with trapezium.
Gamekeeper's Thumb
Rupture of UCL
Often associated with fx at base of proximal phalanx.
Angulation >30 degrees with stress is diagnostic
Boxer's Fracture
Fracture of the 5th metacarpal neck.
Volar angulation and displacement of distal fragment.
External rotation of distal fragment.
Bucket-handle Fracture
Unstable pelvic fracture involving one SI joint and contralateral ischiopubc ramus.
Malgaigne's Fracture
Unstable pelvic fracture involving one SI joint and the ipsilateral ischiopubic ramus.
Often with forshortening of LE and superior displacement of iliac crest.
Duverney's Fracture
Stable pelvic fracture through one iliac wing.
Does not interrupt pelvic ring.
Straddle fracture
Unstable pelvic fracture involving both obturator rings.
Pilon Fracture
Supramalleolar fracture of the distal tibia extending into the tibial plafond.
Often associated with fracture of dsital tib/fib syndesmosis.
MEchanism of injury is axial load (e.g. jumper)
Always intraarticular and comminuted.
Tillaux Fracture
Avulsion of lateral tibial margin.
Juvenile Tillaux is a Salter Harris III becasue the medial growth plate fuses initially.
Triplane fracture
Childhood fracture of distal tibia with three planes:
1. vertical intraarticular fx through epiphyseal
2. horizontal fx through physis
3. oblique metaphyseal fracture
Segond fracture
Small avulsion fx of superolateral proximal tibia.
Often associated with tears of lateral capsular ligaments, ACL and menisci.
Lover's Fracture
Calcaneal fx 2/2 axial loading
Boeler's angle < 20 degrees is diagnostic.
Often occur bilaterally
Usually intraarticular fracture (subtalar joint)
Associated with thoracolumbar burst and pilon fractures.
Not to be confused with calcaneal stress fractures which are seen as vertical linear sclerotic regions.
AC Separation
AC widening > 8mm 2/2 ruptured AC ligament.
CC widening > 13mm 2/2 ruptured CC ligament.
Downward displacement of scapula.
Rockwood Classification:
Grade I: Normal X-Ray
Grade II: Wide AC, normal CC
Grade III: Wide AC and CC
Humeral Head Fractures
4 part Neer classification
4 segments: anatomic neck, surgical neck, grreater tuberosity, lesser tuberosity.
Displacement = > 1 cm separation, or > 45 degrees of angulation.
1 part (no displacement) -> sling.
2 part (disp of one segment) -> closed reduction.
3 part (2 disp segs) -> closed reduction.
4 part (4 disp segs) -> ORIF
Distal Humerus Fractures
Supracondylar, extraarticular
Transcondylar, intraarticular
Intercondylar, intraarticular (T, Y, V shaped)
Radial head fracture
Commonly 2/2 FOOSH (e.g. Essex-Lopresti Fx)
Look for anterior or posterior fat pad (sail) sign.
>3 mm displacement -> ORIF
If comminuted -> excision
Wrist dislocation
Scapholunate dislocation > 60 degrees
Capitolunate dislocation > 20 degrees
VISI (volar tilt of lunate) > DISI (dorsal tilt of lunate)
Acetabular fracture
Letournel classification
Anterior column fx
Posterior column fx
Transverse fx
Comlex (T-shaped) fx
Hip Fractures
Intracapsular: Capital, Subcapital (common), Transcervical

Extracapsular: Intertrochanteric (70%), Subtrochanteric (30%)

AVN occurs in 10-30% of subcapital fractures 2/2 disruption of femoral circumflex artery.
Bumper Fractures
Intraarticular fracture of tibial condyle.
Mechanism is usually a valgus force (e.g. clipped laterally from car bumper) resulting in lateral tibial plateau fx (80%).
Muller classification:
Type I: split (25%)
Type II: depression (25%)
Type III: split-depression (25%)
Type IV: comminuted fx of both tibial condyles.
Ankle Fractures
Weber classification:
A: stable fx through distal fib, below syndesmosis.
B: fx through syndesmosis with partial disruption of tib-fib ligamentous complex.
C: unstable fx through proximal fib with vertical tear of interosseous membrane and complete disruption of tib-fib lig complex.
Often associated with fractures or avulsions of medial maleolus.
Ankle mortis is stable iff 3-4mm space is even.
Tibial Stress Fracture
Zone of sclerosis with periosteal reaction.
Classically occurs in runners.
Thickening of posteromedial aspect of proximal tibia.
Discoid meniscus
Usually lateral meniscus
Normal variant, though more prone to tears.
Bridging of ant + post horns on MRI seen in >=3 consecutive sagital images is diagnostic.
Calcification of the menisci
Associated with various metabolic disorders such as:
CPPD, hyperPTH, hemachromatosis, Wilson's, gout, and collagen vascular dz.
Jefferson's fracture
Ring fractuer of C1 resulting from axial compression injury (e.g. diving.).
Uni of bilateral fx of both anterior and posterior arches of C1.
Open mouth view shows > 2mm overhang of lateral masses of C1.
CT is best at diagnosing this injury.
Treat with halo x 3 months.
Hangman's fracture
Bilateral fractures through C2 pedicle or pars interarticularis.
Anterior dislocation of C2 vertebral body.
Ruptured ALL with avulsion of ant-inf C2.
Prevertebral soft-tissue swelling.
Mechanism is hyperextention and traction injury (e.g. from hanging).
Flexion tear drop fracture
Acute cord syndrome 2/2 severe flexion injury.
Highly unstable.
Tear drop fragment from anterior vertebral body
All five ligaments disrupted
Posterior subluxation of vertebral body and bilateral subluxed or dislocated facets lead to severe narrowind of spinal canal.
May have associated pinous process fracture.
Le Forte Facial fractures
I: floating face - nasal septum, max sinus, pterygoid plates
II: floating maxilla: sygomatic arches not broken
II: floating face: craniofacial dislocation
Zygoma (tripod) fracture
1. Inferior orbital rim and lateral max wall
2. posterior zygomatic arch
3. diastasis of zygomaticofrontal suture
Orbital blow-out fracture
Fracture of floor of orbit 2/2 sudden increase in intraorbital pressure.
Can occasionally have medial wall blowout fx.
Usually inferior rectus muscle entrapment with diplopia on upward gaze.
Best seen on Caldwell and waters views.
X-ray findings: Trap door sign, Opacified maxillary sinus, Orbital emphysema, Opacified ethmoid sinus
Atlanto-occipital dislocation
Complete A-O dislocation is fatal
Prevertebral s.t. swelling
Basion-axial interval > 12 mm is diagnostic.
March fracture
Stress fracture of metatarsal neck
Lisfranc's fracture-dislocation
Dorsal dislocation of tarsometatarsal joints
Most common dislocation of foot
Often 2/2 diabetic neuropathic (Charcot's ) joints.
2 types: Homolateral and divergent.
Associated with fx of base of metatarsals and cuneiform bones.
Dupuytren's fracture
Fracture of fibula above tibiofibular ligament.
Maisonneuves fracture
Spiral proximal fibular fracture Associated with ankle injury.
Implies ligamentous ankle injury with disruption of interosseous membrane and syndesmosis (usually Weber C).
Often missed as it is remote from the site of injury.
May also have medial maleolar fracture.
Jone's fracture
Fx of proximal shaft of 5th metatarsal.
Not due to peroneous brevis avulsion.
High rate of nonunion.
Glomus tumor
Benign vascular tumor of distal phalanx.
Well circumscribed, lytic, and painful.
Alkaptonuria (Ochranosis)
Metabolic bone dz caused by absence of homogentistic acid oxidase.
Increased tissue homogentistic acid.
Black discoloration of cartilage.
Dystrophic calcification of intervertebral disks > cartilage, tendons, ligaments
Generalized osteoporosis.
Hemophilia related arthropathy
Multiple acute hemarthrosis -> chronic synovitis and changes.
Monoarticular (Knee> elbow)
Hemarthrosis / joint effusions
periarticular osteoporosis
subchondral cysts
secondary OA
Square patella, wide interchonylar notch, enlarged radial head, wide trochlear notch.
Asymptomatic unless pathologic fx occurs.
Vertbral body > skull > face
Corduroy appearance 2/2 vertical trabecular pattern is diagnostic.
Ewing's sarcoma
Common childhood malignancy of undifferentiated neuroectodermal origin.
40% 5 year survival
Usually LE diaphysis or flat bones
Aggressive permeative / moth-eaten cortical erosions
May have extraosseous soft tissue mass
Medullary location (but only cortical changes seen on radiograph).
Malignant Fibrous Histiocytoma
Osseous MFH rare despite that MFH is most common S.T. sarcoma in adults.
High local recurrance rate and mets (poor prognosis).
Either priamry or secondary (pagets, post XRT, chondrosarc).
Permeative / moth-eaten often with large s.t. mass.
Clinically and radiographically identical to fibrosarcoma.
Ossifying fibroma
Histologically similar to fibrous dysplasia, osteofibrous dysplasia nad adamatinoma.
Expansile cortical lesion of anterior tibial diaphysis.
Sharp sclerotic border
Radiographically identical to adamatinoma
Younger age group < 20 yr.
Fibrous dysplasia (Lichtenstein-Jafee Dz)
Benign developmental anomaly (5-0 yr old).
Medullary cavity obliterated by woven bone/ fibrous material.
Does not spread.
No malignant transformation.
Associated with hyperthyroid, hyperPTH, percocious puberty (McCune-Albright).
Lucent expansile medullary lesion with ground glass.
Well-defined sclertic margins.
Endosteal scalloping. Weak bone -> pathologic fx -> shepard's crook deformities.
Monostotic (femur) > polyostotic (unilateral).
Multiple Myeloma / Plasmacytoma
Most common primary bone tumor.
Age > 40 yr.
IgG M protein spike on SPEP.
Bence-jone's (light chains) protein on UPEP.
Increased number of plasma cells in marrow of axial skeleton on BM Bx.
Bone pain and anemia.
Multiple lytic puched out lesions.
Bone scan unreliable. Use MRI or skeletal survey for staging instead.
POEMS syndrome in Japan.
Polyneuropathy, Organomegally, Endocrinopathy, M protein, Skin hyperpigmentation.
Double Bubble
= gas in stomach and duodenal bulb with little or no gas distally.
Implies duodenal obstruction
Duodenal atresia (most common) -> Down's.
Anular pancreas (#2).
Eosinophilic granuloma
Centrallt located, usually epiphseal
Skull with well defined lytic bone lesions -> hole within a hole.
May coalesce (geographic skull).
Vertebra plana (+- scoliosis)
Permeative, aggressive cortical destruction in the appendicular skeleton.
Involves other RES organs +/- interstitial or alveolar infiltrates.
Letterer-Siwe = acute disseminated form (10%)
Hand-Schuller-Christian = chronic disseminated form (20%)
LAngerhan's histiocytosis (EG) = isolateed bony involvment (70%)
DDx of pediatric presacral mass
Rectal duplication
Anterior meningocele
DDx of solid renal mass in kids
Wilm's - #1 in kids but rare in newborns.
Mesoblastic nephroma - ONLY solid renal mass seen in newborns < 1 month.
Nephroblastomatosis - subcortical masses associaed with will's

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