Items tagged “variant”
200 results found
Article
Persistent fetal lobulation of the kidneys
Persistent fetal lobulation is a normal variant seen occasionally in adult kidneys. It occurs when there is incomplete fusion of the developing renal lobules. Embryologically, the kidneys originate as distinct lobules that fuse as they develop and grow.
Radiographic features
It is often seen o...
Article
Azygos anterior cerebral artery
An azygos anterior cerebral artery (sometimes spelled azygous) is a rare variant of the circle of Willis where the two A1 segments of the anterior cerebral artery (ACA) join to form a single trunk. As a result, there is no anterior communicating artery. This organization is similar to that seen ...
Article
Septate uterus
A septate uterus is the most common type of congenital uterine anomaly, and may lead to an increased rate of pregnancy loss. The main imaging differential diagnoses are arcuate uterus and bicornuate uterus.
Epidemiology
It is considered the most common uterine anomaly (accounts for ~55% of suc...
Article
Arcuate uterus
An arcuate uterus is a mildly variant shape of the uterus. It is technically one of the Müllerian duct anomalies, but is often classified as a normal variant. It is the uterine anomaly that is least commonly associated with reproductive failure. Arcuate uterus can be characterized with ultrasoun...
Article
Unicornuate uterus
A unicornuate uterus or unicornis unicollis is a type of Müllerian duct anomaly (class II). It is also known as a banana-shaped uterus6,7, because of the shape the single horn assumes, and it usually drains into a single fallopian tube.
Epidemiology
This type can account for ~10% (range 6-13%)...
Article
Müllerian duct anomalies
Müllerian duct anomalies (MDAs) are congenital abnormalities that occur when the Müllerian ducts (paramesonephric ducts) do not develop correctly. This may be as a result of complete agenesis, defective vertical or lateral fusion, or resorption failure.
Epidemiology
MDAs are estimated to occur...
Article
Splenunculus
Splenunculi, also known as supernumerary spleens, accessory spleens, or splenules, are small nodules of spleen that are separate from the rest of the organ.
Epidemiology
They are common, seen in up to 16% of CTs of the abdomen and up to 30% of autopsies 2.
Pathology
Accessory spleens are c...
Article
Total anomalous pulmonary venous return
Total anomalous pulmonary venous return (TAPVR) is a cyanotic congenital heart anomaly with abnormal drainage anatomy of the entire pulmonary venous system. This contrasts with partial anomalous pulmonary venous return (PAPVR) where only part of the pulmonary venous anatomy is abnormal.
In TAPV...
Article
Heterotaxy syndrome
Heterotaxy syndromes refer to abnormal left/right distribution of thoracic and abdominal organs that is neither situs solitus nor situs inversus. They are frequently associated with congenital heart disease and other visceral abnormalities.
Terminology
Isomerism implies mirrored organs, and ca...
Article
Renal agenesis
Renal agenesis refers to a congenital absence of one or both kidneys. If bilateral (traditionally known as the classic Potter syndrome) the condition is fatal, whereas if unilateral, patients can have a normal life expectancy.
Epidemiology
Unilateral renal agenesis affects approximately 1 in ...
Article
Uterine agenesis
Uterine agenesis is the extreme of Mullerian duct anomalies (Class I) where there is a complete absence of uterine tissue above the vagina.
Epidemiology
The uterine agenesis-hypoplasia spectrum accounts for ~10-15% of all Müllerian duct anomalies.
Clinical presentation
Clinical presentation...
Article
Incomplete hippocampal inversion
Incomplete hippocampal inversion describes the situation where the normal inversion of the hippocampus fails to happen during development.
Terminology
Incomplete hippocampal inversion is the most correct description of this finding. Hippocampal malrotation is a term used by some authors 1 alth...
Article
Cardiac bronchus
A cardiac bronchus, sometimes termed accessory cardiac bronchus, is a rare anatomic variant of the tracheobronchial tree, arising from the medial aspect of the bronchus intermedius.
Epidemiology
This anomaly is rare and is reported in ~0.3% (range 0.09-0.5%) of individuals 3-5. There may be a ...
Article
Aberrant left pulmonary artery
Aberrant left pulmonary artery, also known as pulmonary sling, represents an anatomical variant characterized by the left pulmonary artery arising from the right pulmonary artery and passing above the right main bronchus and in between the trachea and esophagus to reach the left lung. It may lea...
Article
Synovial plicae (knee)
Synovial plicae are folds of synovium, thought to represent embryologic remnants. They are common, present in ~90% of arthroscopies 3.
They have been implicated in anterior knee pain and possibly in chondromalacia patellae although their role remains controversial 1,3.
Gross anatomy
Some pl...
Article
Ectopic thyroid
An ectopic thyroid gland is one which is located in a location other than the normal position anterior to the laryngeal cartilages.
Terminology
Ectopic tissue refers to the tissue located outside its normal anatomical position whereas accessory tissue refers to extra tissue located remotely fr...
Article
Lunate morphology
Several classification systems exist for the lunate morphology 1, 2.
Classification
The lunate classification proposed by Viegas et al. is arguably the most relevant 3:
type I lunate: single distal articular facet for the capitate
type II lunate: additional distal articular facet medially f...
Article
Faceless kidney
A faceless kidney refers to one in which the normal appearance of the renal sinus on cross-sectional imaging is absent. It was initially described as a sign of duplication of the collecting system 1 (a slice obtained between the two collecting systems will not demonstrate the normal components o...
Article
Sigmoid kidney
A sigmoid kidney is an uncommon variant of the horseshoe kidney. Whereas the typical horseshoe kidney is fused only at the lower poles, in a sigmoid kidney both the upper and the lower poles are fused 1.
Article
Supracondylar spur
A supracondylar spur, supracondylar process, supratrochlear spur, or avian spur of the distal anteromedial humeral cortex is an anatomical variant present in ~1% 1,2 of the population.
Gross anatomy
The supracondylar spur is typically located on the anteromedial humeral cortex, 5 cm proximal ...