Articles
Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.
782 results found
Article
Splenic cyst
Splenic epithelial cysts, also referred as splenic epidermoid cysts or primary splenic cysts, are unilocular fluid lesions with thin and smooth walls and no enhancement. They represent ~20% of cysts found in the spleen, and are usually an innocuous incidental imaging finding.
Note that most (~8...
Article
Splenic haemangiomatosis
Splenic haemangiomatosis involves multiple, diffuse splenic hemangiomas replacing its entire parenchyma. It is a very rare entity.
Pathology
It can occur as a manifestation of systemic angiomatosis or, less commonly, confined to the spleen (diffuse isolated splenic haemangiomatosis). There is ...
Article
Splenic lesions and anomalies
There are a number of splenic lesions and anomalies:
Congenital anomalies
accessory spleen
wandering spleen
asplenia
polysplenia
splenogonadal fusion
retrorenal spleen
Mass lesions
Benign mass lesions
splenic cyst (mnemonic)
splenic pseudocyst
splenic hemangioma: commonest benign spl...
Article
Splenic pseudocyst
Splenic pseudocysts, also referred as secondary splenic cysts, are acquired cystic lesions not delineated by a true epithelial wall. They represent the majority of the splenic cystic lesions, corresponding to approximately 80% of them (c.f. splenic epithelial cysts). The main causes are:
splen...
Article
Splenomegaly
Splenomegaly refers to enlargement of the spleen. The upper limit of normal adult splenic length is traditionally cited at 12 cm, but lengths upwards of 14 cm can be seen in normal, taller males 7.
Massive splenomegaly is variably defined, including when the spleen is 5 standard deviations abov...
Article
Spontaneous nipple discharge
Spontaneous nipple discharge in a non lactating breast can result from many causes which include:
papillary lesions of breast: present in ~35-50% of cases with spontaneous nipple discharge
intraductal papilloma
fibrocystic change
mammary duct ectasia
ductal carcinoma in situ: 5-21%
Article
Spontaneous splenic rupture
Spontaneous splenic rupture (SSR) (or atraumatic splenic rupture) is rare, especially when compared to traumatic splenic rupture.
Pathology
The pathogenesis of atraumatic splenic rupture is not well understood. Splenomegaly is present in almost all patients (~95%), although rupture of normal ...
Article
Sports injuries - cricket
Cricket is a popular game in Commonwealth countries. Sports injuries in this game can be associated with three positional aspects of the game: bowling, batting or fielding. Radiologists should know the different kind of injuries related to this game for a better clinical association. Injuries ca...
Article
Sports injuries: overhead elbow
Overhead elbow sports injuries are a group of pathologies seen in sports activities with overhead throwing or strokes, e.g. tennis, volleyball, baseball, javelin throwing. There has been a tremendous increase in the number of participants in these sports activities worldwide.
Pathology
During ...
Article
Sports injuries: snowsports
Snowsport injuries cover a broad range of activities from alpine or Nordic skiing, snowboarding, and recreational play (e.g. tobogganing, tubing).
Epidemiology
Snowsports are popular with over 70 million people globally participating each year 1. While the injury rate varies depending on loca...
Article
Sprue
Sprue is the collective term for the malabsorptive gastrointestinal enteropathies although it may be used to refer directly to tropical sprue. It is composed of two entities:
tropical sprue
non-tropical sprue / celiac disease
In each, the radiologic features are not sensitive enough to confir...
Article
Storage disorders
Storage disorders comprise a bewildering collection of inherited metabolic conditions which share the accumulation of a metabolite within various cells in the body due to dysfunction of specific enzymes or transport proteins. Accumulation of metabolites eventually results in cellular and/or orga...
Article
Stroke in children and young adults
Brain ischemia/infarction in children and young adults can result from several causes.
Pathology
Etiology
embolic phenomena
cyanotic heart disease
cardiomyopathies
mitral valve prolapse
Osler-Weber-Rendu syndrome
arterial dissection
trauma
spontaneous
fibromuscular dysplasia
Marfan s...
Article
Subacromial impingement
Subacromial impingement is by far the most common form of shoulder impingement and occurs secondary to attrition between the coracoacromial arch and the underlying supraspinatus tendon or subacromial bursa, leading to tendinopathy and bursitis respectively.
Pathology
Etiology
acromial shape
...
Article
Subarachnoid FLAIR hyperintensity
There are a wide range of causes for subarachnoid FLAIR hyperintensity, both pathological and artifactual.
Differential diagnosis
Pathological causes
subarachnoid hemorrhage
meningitis
leptomeningeal carcinomatosis
FLAIR vascular hyperintensities in acute stroke 1,4,8
moyamoya disease
m...
Article
Subcutaneous abscess
A subcutaneous abscess is a manifestation of a spectrum of soft tissue skin infection which includes cellulitis and necrotizing fasciitis. It is a form of abscess which lies within the dermis and subdermal cutaneous layers. Along with dental abscesses, subcutaneous abscesses are the most common ...
Article
Subcutaneous calcification (differential)
Subcutaneous calcification can be associated with a number of disorders. The list includes:
dermatomyositis
Ehlers-Danlos syndrome
pseudoxanthoma elasticum
basal cell nevus syndrome
subcutaneous lipodystrophy
venous thrombosis
as a manifestation of systemic lupus erythematosus
varicose v...
Article
Subdiaphragmatic free gas
Subdiaphragmatic free gas is one of the ways of detecting presence of free intraperitoneal gas (i.e. pneumoperitoneum). It is the presence of free, extraluminal gas in the anterior subhepatic space.
Radiographic features
Plain radiograph
Subdiaphragmatic free gas is well appreciated as the g...
Article
Subluxed facet joint
Subluxed facet joint is the mildest form of facet dislocation in which the ligamentous injury leads to partial uncovering of facet joint (c.f. complete uncovering in perched facet). This results in mild anterior displacement of one vertebral body on another (anterolisthesis).
Article
Subperiosteal bone resorption
Subperiosteal bone resorption is the most consistent and specific finding of hyperparathyroidism and is virtually pathognomonic of the condition.
Radiographic features
While the terminal tufts of the phalanges are the most commonly involved bones, many others are involved:
tufts of the distal...
Article
Subpulmonic effusion
Subpulmonic effusions (also known as subpulmonary effusions) are pleural effusions that can be seen only on an erect projection. Rather than layering laterally and blunting the costophrenic angle, the pleural fluid lies almost exclusively between the lung base and the diaphragm.
Radiographic fe...
Article
Sunburst appearance (bone)
Sunburst or sunray appearance describes two separate findings in the bone: a periosteal reaction and a trabeculation pattern. It should not be confused with the sunburst sign of meningioma vascularity.
Sunburst periosteal reaction reflects aggressive periostitis. The sunburst appearance occurs...
Article
Superficial siderosis
Superficial siderosis is a rare condition which results from the deposition of hemosiderin along the leptomeninges, with eventual neurological dysfunction.
On imaging, it is classically characterized on MRI as a rim of low signal coating the surface of the brain or spinal cord, particularly not...
Article
Superficial thrombophlebitis
Superficial thrombophlebitis, also called superficial venous thrombosis (SVT), is a pathological condition characterized by the presence of a thrombus in the lumen of a superficial vein, accompanied by inflammatory reaction of adjacent tissues.
Terminology
Some authors, however, reserve the te...
Article
Supernumerary ribs
Supernumerary ribs occur most commonly as a cervical rib arising from C7 or a lumbar rib arising from L1. In extremely rare situations, there can be sacral, coccygeal, intrathoracic, or aberrant lumbar ribs 3. Rarely supernumerary ribs (cervical and lumbar ribs aside) have been found as 'normal'...
Article
Superscan
Superscan is intense symmetric activity in the bones with diminished renal and soft tissue activity on a Tc99m diphosphonate bone scan.
Pathology
This appearance can result from a range of etiological factors:
diffuse metastatic disease
prostatic carcinoma
breast cancer
transitional cell c...
Article
Suprasellar cystic lesions
The differential for suprasellar cystic lesions is large and predominantly includes developmental and neoplastic conditions.
Differential diagnosis
Developmental
arachnoid cyst
craniopharyngioma
Rathke's cleft cyst
dermoid cyst
epidermoid cyst
ependymal cyst
enlarged perivascular spaces...
Article
Surgical sieve (mnemonic)
A surgical sieve is an approach to differential diagnosis that prompts the user to consider various types of pathologies systematically. A surgical sieve does not need to be a mnemonic 2, although many find it easier to remember it when a mnemonic is used. Various versions of this mnemonic exist...
Article
Suspected physical abuse
Suspected physical abuse (SPA), also known as non-accidental injury (NAI) or inflicted injury, in infants and young children represents both ethical and legal challenges to treating physicians.
Radiologists may be the first clinical staff to suspect non-accidental injuries when confronted with ...
Article
Suspicious breast calcifications
Suspicious breast calcifications are calcifications within the breast that have a morphology and/or distribution on mammography indicating a significant probability of malignancy. These merit further workup and biopsy 1.
Radiographic features
Technique
Some calcifications may be more conspicu...
Article
Swan neck deformity (fingers)
Swan neck deformity is a musculoskeletal manifestation of rheumatoid arthritis presenting in a digit, with the combination of:
hyperextension of a proximal interphalangeal (PIP) joint
flexion of a distal interphalangeal (DIP) joint
Pathology
The swan neck deformity characterized by hyperexte...
Article
Symmetrical periosteal reaction
There are a large number of causes for a symmetrical periosteal reaction 1,2:
chronic venous insufficiency
hypertrophic osteoarthropathy
physiologic periostitis, most common cause before 6 months old
Caffey disease
juvenile idiopathic arthritis
pachydermoperiostosis
congenital syphilis
...
Article
Syndactyly
Syndactyly (plural: syndactylies) refers to a congenital fusion of two or more digits. It may be confined to soft tissue (soft tissue syndactyly/simple syndactyly) or may involve bone (bony syndactyly/complex syndactyly).
Epidemiology
The overall estimated incidence is at ~1 per 2,500 to 5,000...
Article
Syndesmophyte
Syndesmophytes are calcifications or heterotopic ossifications inside a spinal ligament or of the annulus fibrosus. They are seen in only a limited number of conditions including:
ankylosing spondylitis
ochronosis
fluorosis
reactive arthritis
psoriatic arthritis
They can be classified as...
Article
Syringobulbia
Syringobulbia is a rare entity and refers to a syrinx that extends into the medulla oblongata 1.
Terminology
Some authors use syringobulbia to refer to a syrinx present in any portion of the brainstem rather than specifically involving the medulla oblongata, and therefore encompassing syringop...
Article
Syrinx
Syrinx (pl. syringes) is the collective name given to hydromyelia, syringomyelia, syringobulbia, syringopontia, syringomesencephaly, and syringocephalus.
Terminology
The use of the general term 'syrinx' has grown out of the difficulty in distinguishing between hydromyelia and syringomyelia usi...
Article
Talar body fractures
Talar body fractures are a subtype of talar fracture, subdivided into:
talar dome osteochondral fracture
posterior talar process fracture
lateral talar process fracture
Article
Talar dislocation
There are many types of talar dislocation given its multiple articulations:
tibiotalar dislocation
subtalar dislocation
total talar dislocation
talonavicular dislocation
Chopart fracture-dislocation
Article
Talar fractures
Talar fractures are an uncommon injury, accounting for <5% of all foot fractures. Recognition of the unique talar anatomy is important for correct diagnosis.
Pathology
Location
talar head fractures
talar neck fractures
talar body fractures
talar dome osteochondral fracture
posterior talar...
Article
Telecanthus
Telecanthus (rare plural: telecanthi) represents an increased intercanthal distance. It is often used interchangeably with hypertelorism, referring to increased distance between the eyes.
Causes and associations
trauma: naso-orbito-ethmoidal (NOE) fractures
ethnic variation
acquired
sinus a...
Article
Temporal bone destructive lesions (differential)
Destructive lesions of the temporal bone (petrous pyramid, middle ear and antrum) have a relatively broad differential including 1:
lesions affecting petrous pyramid
vestibular schwannoma (acoustic neuroma)
meningioma
glioma
neuroma of trigeminal and facial nerve
chordoma
glomus jugulare ...
Article
Temporomandibular joint effusion
Temporomandibular joint (TMJ) effusions are unusual in asymptomatic patients, and thus should trigger a careful search for underlying pathology. It usually precedes osteoarthritis of the TMJ. Effusions are seen in:
TMJ dysfunction
septic arthritis
rheumatoid arthritis (RA)
Radiographic featu...
Article
Tension pneumothorax
Tension pneumothoraces occur when intrapleural air accumulates progressively in such a way as to exert positive pressure on mediastinal and intrathoracic structures. It is a life-threatening occurrence requiring both rapid recognition and prompt treatment to avoid a cardiorespiratory arrest.
A ...
Article
Terminal ileitis (differential)
The differential diagnosis for a terminal ileitis is quite extensive, and includes:
inflammatory bowel disease
Crohn disease (most common)
backwash ileitis due to ulcerative colitis
infectious colitis
Yersinia spp.
Yersinia enterocolitica
Yersinia pseudotuberculosis
Salmonella spp.
Sa...
Article
Terminal tuft mass
There is only a short list of terminal tuft masses, which can arise from the adjacent soft tissues and erode the terminal tuft as well as arising from the terminal tuft itself:
epidermal inclusion cyst: history of penetrating trauma
tenosynovial giant cell tumor: occur laterally
subungual glo...
Article
Terminal zones of myelination
The terminal zones of myelination are located at the posterior aspect of the lateral ventricles (the peritrigonal regions) and are the only part of the cerebral white matter that may exhibit high T2 signal in a normal brain at 2 years of age, when myelination of cerebral white matter normally be...
Article
Testicular cancer
Testicular cancers are the most common neoplasm in men between the ages of 20 and 34 years.
Epidemiology
Testicular cancer is uncommon, accounting for less than 1% of all internal organ malignancies 2.
The demographics of affected individuals depends on the age of the histology of the tumor. ...
Article
Testicular microlithiasis
Testicular microlithiasis is a relatively uncommon condition that represents the deposition of multiple tiny calcifications throughout both testes.
The most common criterion for diagnosis is that of five microcalcifications in one testicle, although definitions have varied in the past. In the ...
Article
Testicular trauma
Testicular trauma is the third most-common cause of acute scrotal pain and may result in various degrees of damage to the testes.
Pathology
Testicular rupture and testicular ischemia/infarct are two severe complications which need to be ruled out. Other injuries that can occur include 1:
test...
Article
The four "Ds" of radiology reporting
The four "Ds" of radiology reporting are the basic sequential tasks that a radiologist performs when reporting/reading a case, whether it be in training, the exam environment or in day-to-day clinical practice.
The 4 "Ds"
Detect
Describe
Diagnosis or differential diagnoses
Decision
By sti...
Article
Third inflow
Third inflow refers to anatomical variants leading to an additional venous inflow to the liver apart from the usual dual blood supply (portal vein and hepatic artery). They tend to be associated with parenchymal pseudolesions (focal hyperenhancement on post-contrast imaging, focal fat infiltrati...
Article
Thoracic aortic dilatation (differential)
There are a number of causes and mimics of thoracic aortic dilatation.
Differential diagnosis
senile ectasia
hypertension
post-stenotic dilatation, e.g. bicuspid aortic valve
thoracic aortic aneurysm
atherosclerosis (usually descending thoracic aorta)
collagen disorders
Marfan syndrome
...
Article
Thoracic aortic stenosis (differential)
The differential for thoracic aortic stenosis includes:
atherosclerosis
aortitis (especially Takayasu arteritis)
radiation
coarctation
pseudocoarctation
Williams syndrome: supravalvular aortic stenosis
congenital rubella syndrome: supravalvular aortic stenosis
Article
Threatened miscarriage
Threatened miscarriage (or threatened abortion) is mainly a clinical term, used when a pregnant woman in first 20 weeks of gestation presents with spotting, mild abdominal pain and contractions, with a closed cervical os 3.
Epidemiology
It occurs in 20-25% of pregnancies and is associated with...
Article
Thyroid inflammatory conditions
A number of inflammatory conditions can affect the thyroid gland, each commonly described as thyroiditis (plural: thyroiditides):
acute thyroiditis
acute suppurative thyroiditis (AST)
autoimmune thyroiditis
subacute lymphocytic thyroiditis (a.k.a. silent thyroiditis or painless subacute th...
Article
Thyroid malignancies
Thyroid malignancies are most commonly primary thyroid cancers but can rarely be metastatic deposits.
Pathology
Classification
Thyroid malignancies can be categorized into the following key subtypes:
primary thyroid cancers
papillary thyroid carcinoma: 60-80% of carcinomas
follicular thyr...
Article
Tibiotalar slant
Tibiotalar slant is the superolateral inclination of the tibial plafond, and results in an ankle valgus deformity. There are a number of causes 1:
trauma, i.e. distal tibial fractures
osteomyelitis and/or septic arthritis
juvenile idiopathic arthritis
haemophilic arthropathy
sickle cell dis...
Article
Tonsillar herniation
Tonsillar herniation is a type of brain herniation characterized by the inferior descent of the cerebellar tonsils below the foramen magnum >3mm 5. Clinically, the presence of tonsillar herniation is often called coning.
The terminology of caudally displaced tonsils is discussed in the article ...
Article
Tonsillitis
Tonsillitis refers to inflammation of any of the tonsils and is one of the most common head and neck infections in adolescents and young adults.
Clinical presentation
Patients may present with a variety of symptoms including painful throat (may be unilateral), dysphagia, fevers, tender cervica...
Article
Torsion (bone)
Torsion in bone refers to as the rotation or contortion along the longitudinal axis of the bone.
The long bones, particularly the femur, humerus and tibia are most commonly affected and torsional abnormalities can be developmental or posttraumatic in nature or can arise from overuse 1.
Torsion...
Article
Torticollis
Torticollis (wryneck) is a clinical finding of head tilt with or without rotational spinal malalignment. It is not a diagnosis in itself and there are a wide range of underlying conditions. It is most common in the pediatric age group.
Pathology
Torticollis can be acute (<1 week) or chronic (...
Article
Total hip arthroplasty
Total hip arthroplasty (THA) or total hip replacement (THR) is an orthopedic procedure that involves the surgical excision of the femoral head and cartilage of the acetabulum and replacement of the joint with articulating femoral and acetabular components. It is a commonly performed procedure us...
Article
Toxoplasmosis vs lymphoma
Toxoplasmosis and lymphoma are frequently differential diagnoses in patients with HIV/AIDS, as these represent the most common brain lesions with mass effect in this population. As treatment is substantially different, distinguishing the two on imaging is important, particularly when the lesion ...
Article
Tracheal and endobronchial lesions
Primary tracheal and endobronchial lesions are generally rare and can be either malignant or benign. The majority of these lesions are malignant.
Pathology
Malignant
primary malignant endobronchial lesions
bronchogenic adenocarcinoma
squamous cell carcinoma: commonest malignant lesion in th...
Article
Tracheal buckling
Tracheal buckling is a normal finding in young infants when it is more flexible. There is typically deviation of the trachea anteriorly and to the right (up to 90°) and any other configuration (i.e. to the left or posteriorly) should raise the possibility of underlying pathology.
Practical poi...
Article
Tracheal masses
The differential for tracheal masses can be rather wide.
For a single mass consider:
metastasis
direct invasion from adjacent organ (lung, thyroid, esophagus and larynx)
distant metastasis (e.g. melanoma, breast, renal, and colon cancer)
primary neoplasms
squamous cell carcinoma: commone...
Article
Tracheal wall thickening
Tracheal wall thickening may have several causes. For diagnostic purposes, tracheal thickening may be categorized by length of airway involvement in order to narrow the differential diagnoses. Note that some etiologies may be associated with either focal or diffuse pattern of involvement.
Diffe...
Article
Traction bronchiectasis
Traction bronchiectasis refers to an etiological subtype of bronchiectasis where there is irreversible dilatation of bronchi and bronchioles within areas of pulmonary fibrosis or distorted lung parenchymal architecture.
Pathology
It can arise from a number of underlying causes which result in ...
Article
Transalar herniation
Transalar (transsphenoidal) herniation describes herniation of brain matter in and around the middle cranial fossa across the greater sphenoid wing and can be ascending or descending. Compression of structures against the sphenoid bone results in symptoms.
Pathology
Transalar herniation is not...
Article
Transient arterial phase respiratory motion-related artifact
Transient arterial phase respiratory motion-related artifact refers to common self-limited dyspnea observed immediately after the administration of gadoxetate disodium during liver MRI studies. The physiopathology behind this phenomenon is poorly understood and its incidence varies among differe...
Article
Transient hepatic attenuation differences
Transient hepatic attenuation differences (THAD) lesions refer to areas of parenchymal enhancement visible during the hepatic artery phase on helical CT. They are thought to be a physiological phenomenon caused by the dual hepatic blood supply. Occasionally, they may be associated with hepatic t...
Article
Transitional aneurysm
Transitional aneurysms, also referred to as transitional paraclinoid aneurysms, are saccular cerebral aneurysms arising from the clinoid-ophthalmic segment of the internal carotid artery (ICA) and near the distal dural ring with potential risk for subarachnoid hemorrhage.
After an anterior turn...
Article
Transtentorial herniation
Transtentorial herniation is a type of cerebral herniation broadly divided into two major types based on the direction of herniation: downwards due to supratentorial mass effect and upward due to infratentorial mass effect.
Downward transtentorial herniation
Downward herniation occurs when the...
Article
Trapped lung
Trapped lung, also known as unexpandable/unexpanded lung, is a term used where there is non-expandable lung after fluid removal, often thoracentesis. It is similar to but not entirely synonymous with the term lung entrapment, which is a similar condition caused by active pleural disease rather t...
Article
Trauma in pregnancy
Trauma is a leading cause of mortality in pregnancy. Pregnancy increases the incidence and severity of abdominal trauma in females.
Epidemiology
Trauma affects up to 7% of pregnancies, and the incidence of pregnancy in level 1 trauma patients is estimated to be ~2% 1.
Pathology
Etiology
9...
Article
Traumatic spinal cord injury
Traumatic spinal cord injury can manifest as a wide variety of clinical syndromes resulting from damage to the spinal cord or its surrounding structures. It can result from minor injury if the spine is weakened from disease such as ankylosing spondylitis or if there is pre-existing spinal stenos...
Article
Triphalangeal thumb
Triphalangeal thumb is considered a form of pre-axial polydactyly.
Epidemiology
Triphalangeal thumbs have an incidence of 1 in 25,000 7.
Pathology
A triphalangeal thumb, as the name implies, has three phalanges instead of the usual two. There is an autosomal dominant genetic transmission 8,...
Article
Troponin
Troponin is a protein of key importance in the functioning of skeletal and cardiac muscle. It forms part of the contractile mechanism, and comprises three main subunits: troponin C, troponin I, and troponin T.
Troponin elevation
Elevation of serum troponin can occur from a number of causes an...
Article
Tuberculosis (intracranial manifestations)
Tuberculosis of the central nervous system can result from either hematogenous spread from distant systemic infection (e.g. pulmonary tuberculosis) or direct extension from local infection (e.g. tuberculous otomastoiditis).
Intracranial manifestations of tuberculosis are protean and can affect ...
Article
Tubulinopathy
Tubulinopathies refer to a wide spectrum of cortical malformations that result from defects in genes encoding the tubulin protein that regulates neuronal migration during brain development.
Clinical presentation
Some series report a high prevalence of seizures during infancy which may the init...
Article
Tumor ablation
Tumor ablation, or image-guided tumor ablation, is the direct application of chemical or energy-based (i.e. thermal and nonthermal) treatments to cause local tumor destruction. Techniques include:
energy-based techniques
thermal ablation
radiofrequency ablation (RFA)
microwave ablation (MWA)...
Article
Tumors of muscular origin
There are a number of tumors of muscular origin, which overall are relatively uncommon, representing ~2% of benign soft tissue tumors and ~10% of malignant soft tissue tumors 1.
Pathology
The tumors can be divided according to the type of muscle fiber:
Skeletal muscle origin
benign
rhabdom...
Article
Tumors of the chest wall (differentials)
Tumors of the chest wall are varied, some of which are found most often in this region. They can be divided into benign and malignant tumors and into those which arise in the ribcage and those of soft tissue density.
Benign
Benign tumors include 1,3,4:
soft tissue
hemangioma: common
lymphan...
Article
Tumors of the male urethra
Tumors of the male urethra are uncommon. They can be categorized both on the grounds of histology and location.
Histology
squamous cell carcinoma of the urethra: 80%
urothelial/transitional cell carcinoma of the urethra: 15% (predominantly posterior urethra)
adenocarcinoma of the urethra: 5%...
Article
Tumors of the small intestine
The small intestine is rarely the site of malignant tumors, although it accounts for ~75% of the entire length of the GI tract and more than 90% of the mucosal surface. Approximately 40 different histologic tumor types have been described.
In this article, an overview will be given of the most...
Article
Tumors that metastasize to bone (mnemonic)
Tumors that metastasize to bone may be remembered using the mnemonic "lead kettle" spelled PBKTL (lead is Pb on the Periodic Table).
PB-KTL
Mnemonic
P: prostate
B: breast
K: kidney
T: thyroid
L: lung
For females, breast and lung are the most common primary sites; nearly 80% of cancers th...
Article
Twin pregnancy
Twin pregnancies are the most common multifetal pregnancies.
Epidemiology
Multifetal pregnancies account for ~1% of all pregnancies but are seen in much higher numbers in populations where in vitro fertilisation (IVF) is a common practice.
Classification
A twin pregnancy can be broadly cate...
Article
Ulnar variance
Ulnar variance (also known as Hulten variance) refers to the relative lengths of the distal articular surfaces of the radius and ulna.
Ulnar variance may be:
neutral (both the ulnar and radial articular surfaces at the same level)
positive (ulna projects more distally)
negative (ulna projec...
Article
Ultrasound appearances of liver metastases
Ultrasound appearance of liver metastases can have bewildering variation, and the presence of hepatic steatosis can affect the sonographic appearance of liver lesions.
Radiographic features
Ultrasound
Patterns do exist between ultrasound appearance of the liver metastases and the likely prima...
Article
Umbilical cord cyst
Umbilical cord cysts can refer to any cystic lesion associated with the umbilical cord. They can be single (commoner) or multiple.
Epidemiology
They may be seen in ~3% of pregnancies in the first trimester 8.
Pathology
Umbilical cord cysts can represent either true or false cysts:
true cyst...
Article
Unilateral axillary lymphadenopathy (differential)
Unilateral axillary lymphadenopathy while being more concerning than bilateral axillary lymphadenopathy can still arise from a variety of benign, as well as malignant, causes.
Benign
mastitis
other regional infective causes
tuberculosis
ipsilateral arm infection, e.g. cellulitis
silicone i...
Article
Unilateral facet dislocation
Unilateral facet dislocation is a relatively stable type of facet dislocation.
Pathology
Mechanism
Flexion/distraction associated with rotation. The inferior articular facet of vertebral above moves over the superior facet of the vertebral below and becomes locked. It usually affects C4-C5 or...
Article
Unilateral pulmonary edema
Unilateral pulmonary edema represents only 2% of cardiogenic pulmonary edema with predilection for the right upper lobe and is strongly associated with severe mitral regurgitation 1, 2. It is hypothesized that the regurgitation jet is directed towards the right superior pulmonary vein thus prefe...