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.
1,148 results found
Article
≤11 ribs (differential)
≤11 ribs is associated with a number of congenital abnormalities and skeletal dysplasias, including:
Down syndrome (trisomy 21)
campomelic dysplasia
kyphomelic dysplasias
asphyxiating thoracic dysplasia (Jeune syndrome)
short rib polydactyly syndromes
trisomy 18
chromosome 1q21.1 deletion...
Article
Abdominal hernia
Abdominal hernias (herniae also used) may be congenital or acquired and come with varying eponyms. They are distinguished primarily based on location and content. 75-80% of all hernias are inguinal.
Content of the hernia is variable, and may include:
small bowel loops
mobile colon segments (s...
Article
Abdominal opacities
An opacity projecting over the abdomen has a broad differential. Possibilities to consider include:
foreign bodies
ingested, e.g. coins, batteries, bones, etc
artifacts, e.g. object attached to the cloth of the patient like a safety pin or button
iatrogenic, e.g. hemostatic clips, gastric ba...
Article
Abdominal trauma
Abdominal trauma is usually divided into blunt and penetrating trauma.
Findings of abdominal trauma
haemoperitoneum
splenic trauma: most common
hepatic trauma
renal trauma
pancreatic trauma
gastrointestinal tract (bowel) trauma:
proximal jejunum is most commonly affected by blunt trauma,...
Article
Abdominoschisis
Abdominoschisis refers to a split or defect in the abdominal wall. Some authors use the term synonymously with a gastroschisis. When the defect continues into the thoracic region it is termed a thoraco-abdominoschisis. A large abdominoschisis is considered part of the limb body wall complex 2.
...
Article
Abnormal bowel wall attenuation patterns
Abnormal bowel wall attenuation patterns on CT scan can be grouped under five categories:
white enhancement
gray enhancement
water halo sign
fat halo sign
black attenuation
The first three patterns are seen on contrast studies.
White enhancement
It is defined as uniform enhancement of th...
Article
Abnormally thickened endometrium (differential)
Abnormally thickened endometrium on imaging may occur for a number of reasons which may be categorized based on whether or not they are related to pregnancy. Etiologies may also be classified based on whether the patient is premenopausal or postmenopausal.
Differential diagnosis
Pregnancy-rela...
Article
Abscess
Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1:
a central core consisting of necrotic inflammatory cells and local tissue
peripheral halo of viable neutrophils
surrounded by a 'capsule' with dilated blood vessel...
Article
Absent fetal stomach on ultrasound (differential)
Non-visualization of the fetal stomach on ultrasound can occur with various physiological as well as pathological processes. It becomes a significant sonographic observation >14 weeks of gestation (about the time the fetus begins to swallow).
Causes include:
physiological emptying: transient
...
Article
Absent septum pellucidum
An absent septum pellucidum may rarely be an isolated finding, or more commonly be seen in association with a variety of conditions.
Epidemiology
The septum pellucidum is partly or entirely absent in 2 or 3 individuals per 100,000 in the general population.
Pathology
An absent septum pelluc...
Article
Achilles tendon thickening
Achilles tendon thickening can occur for a number of reasons.
The Achilles tendon has an average AP diameter of 6 mm 1. Thickening of the tendon is when it exceeds 8 mm in AP diameter and can result from:
Achilles tendinosis/tear
post-surgical thickening
retrocalcaneal bursitis
degeneration...
Article
Acute abdominal pain
Acute abdominal pain is a common acute presentation in clinical practice. It encompasses a very broad range of possible etiologies and diagnoses, and imaging is routinely employed as the primary investigative tool in its modern management.
Terminology
A subgroup of patients with acute abdomina...
Article
Acute airspace opacification with lymphadenopathy (differential)
Acute airspace opacification with lymphadenopathy is a subset of the differential diagnosis for generalized airspace opacification and includes:
post-obstructive causes (usually chronic, but 'new' changes can occur)
primary lung cancer
pulmonary metastases
lymphoma/leukemia
infection
prim...
Article
Acute aortic syndrome
Acute aortic syndrome (AAS) describes the presentation of patients with one of a number of life threatening aortic pathologies that give rise to aortic symptoms.
The spectrum of these aortic emergencies include:
aortic dissection
aortic intramural hematoma
penetrating atherosclerotic ulcer
...
Article
Acute basilar artery occlusion
Acute occlusion of the basilar artery may cause brainstem or thalamic ischemia or infarction. It is a true neuro-interventional emergency and, if not treated early, brainstem infarction results in rapid deterioration in the level of consciousness and ultimately death. It is one of the posterior ...
Article
Acute bilateral airspace opacification (differential)
Acute bilateral airspace opacification is a subset of the larger differential diagnosis for airspace opacification. An exhaustive list of all possible causes of acute bilateral airspace opacities is long, but a useful way to consider the huge list is via the material within the airways:
infecti...
Article
Acute gastritis
Acute gastritis is a broad term that encompasses a myriad of causes of gastric mucosal inflammation.
Epidemiology
Depends on the etiology (see below).
Clinical presentation
asymptomatic
epigastric pain/tenderness
nausea and vomiting
loss of appetite
Pathology
Etiology
infection: H. py...
Article
Acute hepatitis
Acute hepatitis occurs when the liver suffers an injury with a resulting inflammatory reaction. The cause of the injury can happen in multiple different ways, and imaging findings are often non-specific. Acute hepatitis is a clinical diagnosis and normal imaging appearance of the liver does not ...
Article
Acute myeloid leukemia
Acute myeloid leukemia (AML), also referred to as acute myelogenous leukemia, is a hematological malignancy characterized by the abnormal clonal proliferation of immature myeloid precursors (myeloblasts) or poorly differentiated cells of the hematopoietic system. It primary infiltrates the bone ...
Article
Acute unilateral airspace opacification (differential)
Acute unilateral airspace opacification is a subset of the differential diagnosis for airspace opacification.
Differential diagnosis
The exhaustive list of all possible causes would be huge, but a useful framework includes:
pus, i.e. infection
bacterial pneumonia
fungal pneumonia
viral p...
Article
Acute vs chronic ischemic stroke
Differentiating between acute and chronic infarction on a CT brain is an important skill for many health professionals particularly in the emergency setting:
pathology
acute: cytotoxic edema
chronic: encephalomalacia; Wallerian degeneration
hypoattenuation
acute: more dense than CSF
chroni...
Article
Adenosis of the breast
Adenosis of the breast is a benign lobulocentric proliferative process in which lobules are enlarged and increased in number in addition to an increased number of glands within each lobule.
Pathologically subclassified into three main subtypes which include:
sclerosing adenosis of the breast
...
Article
Adhesive atelectasis
Adhesive atelectasis refers to the specific form of lung atelectasis that occurs due to the decrease or absence of pulmonary surfactant produced by type II pneumocytes. Without sufficient surfactant the alveoli collapse due to increased surface tension. It is most commonly seen in the neonate wi...
Article
Adrenal calcification
Adrenal calcification is not a rare finding in healthy asymptomatic people and is usually the result of previous hemorrhage or tuberculosis. Addison disease patients only occasionally develop calcification.
Pathology
Etiology
Hemorrhage
sepsis: Waterhouse-Friderichsen syndrome
blunt abdomi...
Article
Adrenal cyst
Adrenal cysts are rare lesions and are commonly incidental findings.
Epidemiology
Adrenal cysts are reported to be rare with an incidence of <1% 1.
Clinical presentation
Patients can present with pain or swelling, although a significant portion (~40%) are incidental findings 1,3.
Patholo...
Article
Adrenal gland tumors
Despite its small size, the adrenal gland is affected by a relatively large number of neoplastic entities:
adrenal adenoma
adrenal myelolipoma
adrenal cortical carcinoma
adrenal pheochromocytoma
adrenal neuroblastoma
adrenal metastases
See also
adrenal lesions: for a more general list of...
Article
Adrenal hemorrhage
Adrenal hemorrhage can result from a variety of traumatic and non-traumatic causes. When unilateral, it is often clinically silent. In contrast, bilateral adrenal hemorrhage can lead to catastrophic adrenal insufficiency.
Clinical presentation
The large majority of patients with unilateral adr...
Article
Adrenal lesions (differential)
Adrenal lesions cover a broad spectrum from benign to neoplastic entities. Due to increased use of cross-sectional imaging they are frequently detected as incidental lesions (incidentalomas). If found incidentally, please refer to the Management of Incidental Adrenal Masses: American College of ...
Article
Adrenal tuberculosis
Tuberculous adrenalitis is the result of adrenal mycobacterium tuberculosis (TB) infection. Its incidence has decreased in the western world with the declining incidence of tuberculosis.
Pathology
As the tuberculous infection causes destruction of the adrenal cortex, primary adrenal insufficie...
Article
Adult cervical lymphadenopathy (differential)
Cervical lymphadenopathy in an adult can result from a vast number of conditions. They include:
malignancy
metastases
from head and neck tumors
lymphoma
other neoplastic lesions
Castleman disease
Kaposi sarcoma
infection
bacterial infection
viral infection
Epstein-Barr virus
herpes ...
Article
AIDS-defining illness
AIDS-defining illnesses are conditions that in the setting of a HIV infection confirm the diagnosis of AIDS, and do not commonly occur in immunocompetent individuals 2. According to the CDC surveillance case definition 1, they are:
Infectious
bacterial infections: multiple or recurrent
candid...
Article
Air crescent sign (lung)
An air crescent sign describes the crescent of air that can be seen in invasive aspergillosis, semi-invasive aspergillosis or other processes that cause pulmonary necrosis. It usually heralds recovery and is the result of increased granulocyte activity.
Terminology
It should not be confused wi...
Article
Air space opacification
Air space opacification is a descriptive term that refers to filling of the pulmonary tree with material that attenuates x-rays more than the surrounding lung parenchyma. It is one of the many patterns of lung opacification and is equivalent to the pathological diagnosis of pulmonary consolidati...
Article
Air space opacities
The differential for air space opacities is extensive, and needs to be interpreted in context of chronicity (previous imaging) and clinical context. It is therefore useful to divide airspace opacities as follows:
acute airspace opacities with lymph node enlargement
acute airspace opacities: un...
Article
Airway foreign bodies in children
Airway foreign bodies in children are potentially fatal, which is why immediate recognition is important. Unfortunately, delayed diagnosis is common.
Epidemiology
Children under the age of four years are at increased risk of foreign body (FB) aspiration, with a slight male predominance 1.
Cl...
Article
Alpha fetoprotein
Alpha fetoprotein (AFP) is an important plasma protein synthesized by the yolk sac and fetal liver. In adults its main utility is as a tumor marker, primarily for hepatocellular carcinoma or teratoma. Functionally it is the fetal homologue of albumin, i.e. it acts as a major carrier protein in t...
Article
Altered breast density between two mammograms
Mammographic screening detects early breast cancers and thereby reduces potential mortality. However, its sensitivity is inversely related to breast density 1.
Altered density between two mammograms can arise in a number of situations:
Affecting both breasts:
interval commencement/cessation ...
Article
Alternating radiolucent and radiodense metaphyseal lines
Alternating radiolucent and radiodense metaphyseal lines can be seen with a number of conditions and the differential diagnosis is wide:
growth arrest lines
bisphosphonate therapy
rickets: especially those on prolonged treatment, e.g. vitamin D dependent rickets
osteopetrosis
chemotherapy
...
Article
Amorphous calcification within breast
Amorphous or indistinct calcifications are a morphological descriptive term for breast calcification and are defined as having small, hazy, faint calcifications with no clearly defined shape or form.
Radiographic features
80-200 micrometer in diameter
small, hazy calcification
often magnifi...
Article
Ampullary tumor
The term ampullary tumor generally refers to either benign or malignant neoplasms that arise from the glandular epithelium of the ampulla of Vater, including 1:
ampullary adenoma (adenoma of ampulla of Vater)
ampullary carcinoma (carcinoma of ampulla of Vater)
According to some authors, ampul...
Article
Angiosarcoma - bone
Angiosarcoma of bone is a malignant vascular tumor of bone. These are rare and account for less than 1% of malignant bone tumors. The majority of these tumors arising in bone are primary; however, a tiny percentage are either radiation-induced or associated with bone infarction
Epidemiology
Mo...
Article
Ankle impingement syndromes
There are several ankle impingement syndromes. They are characterized by limited range of motion and pain on attempting specific movements about the joint and often in a load-bearing position. They have variable etiology and pathogenesis. They are best classified according to location.
The key ...
Article
Anoxic brain injury
Anoxic brain injury, also known as global hypoxic-ischemic injury, is seen in all age groups (from antenatal to the elderly) as a result of numerous etiologies. The pattern of injury depends on a number of factors including:
age of the patient (brain maturity)
neonatal hypoxic-ischemic encepha...
Article
Anterior inferior cerebellar artery (AICA) infarct
Anterior inferior cerebellar artery (AICA) territory infarcts are much less common than posterior inferior cerebellar artery (PICA) infarcts. AICA generally arises from the caudal third of the basilar artery and supplies the lateral pons, inner ear, middle cerebellar peduncle and the anterior in...
Article
Anterior knee pain
Anterior knee pain is common with a variety of causes which can be divided anatomically using a layered approach1 from superficial to deep:
Superficial soft tissues
prepatellar bursitis
Morel-Lavallée lesion
infrapatellar bursitis
Extensor mechanism
quadriceps tendinosis / partial tear
q...
Article
Anterior vertebral body beaking
Anterior vertebral body beaking occurs in a number of conditions and may emanate from the central portion or the lower third of the vertebral body.
Middle third
Morquio syndrome 1 (middle for Morquio)
Lower third
Hurler syndrome 2
achondroplasia 3
pseudoachondroplasia 4
cretinism 5
Down ...
Article
Aortic nipple
An aortic nipple is seen in about 10% of PA chest x-rays on the lateral surface of the aortic arch/aortic knob. It represents the left superior intercostal vein.
When prominent, superior vena cava obstruction should be considered as the left superior intercostal vein serves as a collateral path...
Article
Aortopulmonary window (radiograph)
The aortopulmonary (aortic-pulmonary or AP) window (also known as APW, but see 'Terminology' below) is a radiological mediastinal space seen on frontal chest radiographs.
Terminology
The term "aortopulmonary window" (also called an aortopulmonary septal defect) can also refer to a rare form of...
Article
Aphthoid ulceration
Aphthoid ulcers are shallow ulcers of the gastrointestinal mucosa.
Pathology
Etiology
infective inflammatory conditions
Yersinia enterocolitis
amoebic enterocolitis
cytomegalovirus enterocolitis
noninfective inflammatory conditions
Crohn disease
idiopathic granulomatous gastritis
vascu...
Article
Apical pleural cap
Apical pleural cap refers to a curved density at the lung apex seen on chest radiograph.
Epidemiology
The frequency of apical pleural thickening increases with age 3.
Pathology
It arises from a number of causes:
pleural thickening/scarring
idiopathic: chronic ischemic etiology is favored f...
Article
Apple core sign (colon)
The apple core sign, also known as the napkin ring sign (bowel), is most frequently associated with constriction of the lumen of the colon by a stenosing annular colorectal carcinoma.
Differential diagnosis
The appearance of the apple-core lesion of the colon also can be caused by other diseas...
Article
Areae gastricae
Areae gastricae are a normal finding on double contrast images of the stomach.
Radiographic features
fine reticular network of barium-coated grooves between 1-5 mm islands/areas of gastric mucosa
may be seen in ~70-80% of patients if there is adequate high-density barium coating of the stomac...
Article
Artery of Percheron territory infarct
Artery of Percheron territory infarct is rare, on account of the relative rarity of the artery of Percheron, and presents with a variety of signs and symptoms collectively termed the paramedian thalamic syndrome. It is a type of posterior circulation infarction.
On imaging, it is classically ch...
Article
Asbestos related diseases
Asbestos related disease, in particular affecting the lung, comprise of a broad spectrum of entities related to the inhalational exposure to asbestos fibers. They can be divided into benign and malignant changes 1-3.
Benign pleural and parenchymal lung disease
asbestos related benign pleural d...
Article
Ascending aorta dilatation
Dilatation of the ascending aorta is a common finding in the elderly but unusual in younger patients.
Pathology
In adults, an ascending aortic diameter greater than 4 cm is considered to indicate dilatation 4. Aneurysmal dilatation is considered when the ascending aortic diameter reaches or ex...
Article
Aseptic loosening of hip joint replacements
Aseptic loosening is considered relatively common complication of hip joint replacements. It is usually considered a long-term complication and is often considered as the most common complication 3.
Pathology
Aseptic loosening can occur as a result of inadequate initial fixation, mechanical lo...
Article
Aspiration pneumonia
Aspiration pneumonia is caused by a direct chemical insult due to the entry of a foreign substance, solid or liquid, into the respiratory tract.
Clinical presentation
Aspiration may be clinically silent, or it may present with dyspnea, cough, or fever. The clinical and radiographic features de...
Article
Asplenia syndrome
Asplenia syndrome, also known as right isomerism or Ivemark syndrome, is a type of heterotaxy syndrome.
Epidemiology
There is an increased male predilection. Asplenia syndrome is usually diagnosed in neonates 4.
Clinical presentation
In contrast to polysplenia syndrome, most patients die bef...
Article
Asymmetrical density in mammography
Asymmetrical mammographic density, or more simply asymmetries, is a spectrum of morphological descriptors for a unilateral fibroglandular-density finding seen on one or more mammographic projections that does not meet criteria for a mass.
The criteria for an asymmetry includes that it is seen o...
Article
Asymmetry in breast size
Asymmetry in breast size can arise from a number of factors.
Pathology
Breasts are rarely absolutely the same size or volume. Normal variation is common. Most females have slight discrepancies in breast size. Asymmetric progressive breast enlargement is unusual but known. The role of the breas...
Article
Athletic pubalgia
Athletic pubalgia refers to pain around the pubic symphysis and can have different causes, including what has become known as sports hernia or sportman's hernia and osteitis pubis.
Athletic pubalgia is a clinical syndrome of chronic lower pelvic and groin pain, usually encountered in athletes. ...
Article
Atlantodental interval
The atlantodental interval (ADI), as the name suggests, is the horizontal distance between the anterior arch of the atlas and the dens of the axis, used in the diagnosis of atlanto-occipital dissociation injuries and injuries of the atlas and axis.
It is the distance (in mm) between the posteri...
Article
Atraumatic fracture
Atraumatic fractures, as the name suggests, occur with no trauma or minimal trauma that would not normally be expected to result in a fracture 1. They can be:
stress fractures
fatigue fracture
insufficiency fracture
atypical fractures, e.g. bisphosphonate-related proximal femoral fractures
...
Article
Autoimmune thyroiditis
Autoimmune thyroiditis (plural: thyroiditides) (AIT) refers to a group of conditions in which there is inflammation of the thyroid gland secondary to thyroid autoantibodies.
Epidemiology
They are the most common thyroid disease group in the pediatric population 5.
Pathology
Entities that fal...
Article
Avulsion fractures of the knee
Avulsion fractures of the knee are numerous due to the many ligaments and tendons inserting around this joint. They include 1:
anterior cruciate ligament avulsion fracture
posterior cruciate ligament avulsion fracture
avulsion of the medial collateral ligament
origin of MCL avulsion fracture...
Article
Bands in gestational sacs
Band like structures in the gestational sac is not an uncommon finding in the first trimester or second ultrasounds and can represent a number of varying conditions
These include
uterine synechiae
amniotic bands
amniotic shelf
circumvallate placenta
chorio-amniotic separation
velamentous ...
Article
Bartholin gland tumors
Bartholin gland tumors represent neoplasms of the Bartholin glands.
They include:
squamous cell carcinoma of the Bartholin gland: tends to be the most common histological subtype
adenocarcinoma of the Bartholin gland
adenoid cystic carcinoma of the Bartholin gland
Article
Barton fracture
Barton fractures are fractures of the distal radius. It is also sometimes termed the dorsal type Barton fracture to distinguish it from the volar type or reverse Barton fracture.
Barton fractures extend through the dorsal aspect to the articular surface but not to the volar aspect. Therefore, i...
Article
Basal ganglia and thalamus signal abnormalities
Basal ganglia and thalamus signal abnormalities occur in a wide variety of conditions. Ischemia/hypoxia, metabolic disorders and toxins, particularly those that affect the respiratory chain, have a predilection for affecting the basal ganglia as they are highly metabolically active.
They can b...
Article
Basal ganglia calcification
Basal ganglia calcification is common and is seen in approximately 1% of all CT scans of the brain, depending on the demographics of the scanned population. It is seen more frequently in older patients and is considered a normal incidental and idiopathic finding in an elderly patient but should ...
Article
Basal ganglia T1 hyperintensity
There are many causes of basal ganglia T1 hyperintensity, but the majority relate to deposition of T1-intense elements within the basal ganglia such as:
calcium
idiopathic calcification
calcium and phosphate abnormalities
hepatic failure
acquired non-wilsonian hepatocerebral degeneration
W...
Article
Basal ganglia T2 hyperintensity
The causes of basal ganglia T2 hyperintensity can be remembered using the mnemonic LINT:
lymphoma
ischemia
hypoxia
venous infarction (internal cerebral vein thrombosis)
neurodegenerative / metabolic
autoimmune encephalitis (e.g. anti-D2 dopamine antibody encephalitis)
Creutzfeldt-Jakob di...
Article
Basal ganglia T2 hypointensity
Basal ganglia T2 hypointensities can be caused by any of the following and is commonly remembered using the mnemonic ChOMP.
childhood hypoxia
old age
multiple sclerosis
Parkinson disease: more in globus pallidus
Parkinson-plus syndrome: more in putamen
deoxyhemoglobin of hemorrhage
hemosi...
Article
Basilar invagination
Basilar invagination, also called basilar impression, is a congenital or acquired craniocervical junction abnormality where the tip of the odontoid process projects above the foramen magnum.
Terminology
The terms basilar invagination and basilar impression are often used interchangeably becau...
Article
Basion-axial interval
The basion-axial interval (BAI), as the name suggests, is the horizontal distance between the basion and the posterior cortex of the axis, used in the diagnosis of atlanto-occipital dissociation injuries.
It is the distance (in mm) between the basion and the superior extension of the posterior ...
Article
Basion-dens interval
The basion-dens interval (BDI), as the name suggests, is the distance between the basion and the tip of the dens, used in the diagnosis of atlanto-occipital dissociation injuries.
It is the distance from the most inferior portion of the basion to the closest point of the superior aspect of the ...
Article
Bat wing opacities (lungs)
Bat's wing or butterfly pulmonary opacities refer to a pattern of bilateral perihilar shadowing. It is classically described on a frontal chest radiograph but can also refer to appearances on chest CT 3-4.
Differential diagnosis
Bat's wing pulmonary opacities can be caused by:
pulmonary edema...
Article
Benign liver tumors (pediatric)
Pediatric benign liver tumors are a relatively rare, but important group of conditions. Importantly, the commonest cause of a benign liver tumor is specific to the pediatric population. The list in descending order of frequency is:
infantile hepatic hemangioma (previously hemangioendothelioma)
...
Article
Benign lytic bone lesions
Benign lytic bone lesions encompass a wide variety of entities. A useful starting point is the FEGNOMASHIC mnemonic.
This article is a stub, which means it needs more content. You can contribute to Radiopaedia too. Just register and click edit... every little bit helps.
See also
malignant l...
Article
Benign metastasizing tumors
There are a number of benign metastasizing tumors:
benign metastasizing meningioma 1,2
benign metastasizing leiomyoma 3
primary adenoma of thyroid 4
giant cell tumor of bone 5
Article
Benign minor salivary gland pathology
Benign minor salivary gland pathology is a broad term that encompasses a number of relatively uncommon pathologies that affect the minor salivary glands of the head and neck:
salivary retention cysts
benign neoplasms
pleomorphic adenoma
Article
Benign esophageal lesions
Benign esophageal lesions are less symptomatic than malignant esophageal lesions, making up for only 1% of clinically apparent esophageal lesions.
Pathology
esophageal leiomyoma (>50%)
may calcify
esophageal fibrovascular polyp (~12.5%)
may contain fat
esophageal duplication cyst (10%)
oe...
Article
Benign tumors and tumor-like lesions of the gallbladder
The gallbladder and extrahepatic bile ducts play host to a surprisingly large number of benign tumors and tumor-like lesions which may be visible on imaging. In the gallbladder, most of them are detected incidentally, whereas in the bile ducts they are usually found in symptomatic patients (obst...
Article
Bentall procedure
Bentall procedure is performed for the repair of ascending aortic root lesions. Typically the native aortic root and aortic valve are replaced with a composite graft that comprises both ascending aortic and aortic valve grafts, to which the coronary arteries are anastomosed.
History and etymolo...
Article
Bent bone dysplasias (differential)
Bent bone dysplasias are a class of dysplasia included in a 2010 classification of genetic skeletal disorders 1.
campomelic dysplasia
Stuve-Weidemann dysplasia
kyphomelic dysplasias, a diverse class, including
congenital bowing of the long bones
cartilage-hair hypoplasia (CHH; metaphyseal d...
Article
Beta-hCG
Beta-hCG (bHCG or β-hCG) is a sex hormone found in the mother's blood serum that can be used to help interpret obstetric ultrasound findings.
Beta-hCG levels may be used in three ways in the clinical setting of pregnancy:
qualitatively, for presence/absence of fetal tissue
more often determin...
Article
Bicaudate index
The bicaudate index is the ratio of width of two lateral ventricles at the level of the head of the caudate nucleus to distance between outer tables of skull at the same level. It can be a useful marker of ventricular volume and in the diagnosis of hydrocephalus.
Article
Bilateral adrenal gland enlargement
The differential for bilaterally enlarged adrenal glands is relatively limited:
adrenal hyperplasia
micronodular adrenal hyperplasia
macronodular adrenal hyperplasia
adrenocorticotropin (ACTH)-independent macronodular adrenocortical hyperplasia (AIMAH) 2
adrenal metastases
adrenal hemorrha...
Article
Bilateral axillary lymphadenopathy (differential)
Bilateral axillary lymphadenopathy can result from a number of causes and generally implies a systemic process. They include:
autoimmune diseases, e.g.:
rheumatoid arthritis
scleroderma
dermatomyositis 5
systemic lupus erythematosus (SLE)
psoriasis
Sjögren syndrome
lymphoma
leukemia
di...
Article
Bilateral middle cerebellar peduncle lesions
Involvement of both middle cerebellar peduncles is uncommon, but has a relatively long list of differential diagnoses, including 1:
neurodegenerative diseases
multiple systemic atrophy (MSA)
olivopontocerebellar atrophy
Shy-Drager syndrome
spinocerebellar atrophy
metabolic diseases
adre...
Article
Bilateral renal enlargement
Bilateral renal enlargement can arise from a number of causes which include 1:
diabetic nephropathy (common)
renal involvement with lymphoma
acute interstitial nephritis
vasculitis / autoimmune
HIV nephropathy
leukemia
autosomal recessive polycystic kidneys (ARPKD)
adult dominant polycys...
Article
Bilateral testicular lesions
Bilateral testicular lesions have a relatively limited differential diagnosis.
Differential diagnosis
Neoplastic
lymphoblastic leukemia (acute or chronic)
lymphoma (non-Hodgkin's)
primary testicular lymphoma is rare but the testes are often the site of lymphoma/leukemia recurrence due to ...
Article
Bilateral thinning of the parietal bones
Bilateral thinning of the parietal bones, also known as biparietal osteodystrophy, is an uncommon, slowly progressive acquired disease of middle-aged people with slight female predilection. It is typically an incidental finding.
Pathology
The etiology is unknown but is thought to be an age-re...
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