Items tagged “variant”
200 results found
Article
Bilobed testis
Bilobed testis, also known as incomplete unilateral polyorchidism, is a very rare congenital variant in children, and considered to be an incomplete form of polyorchidism.
Epidemiology
Associations
malignancy
cryptorchidism
inguinal hernia
hydrocele
infertility
varicocele
testicular tor...
Article
Occipital vertebra
Occipital vertebrae are rare anatomical variants that result from incomplete or aberrant fusion of occipital bone ossification centers. There is a broad spectrum of occipital vertebrae, the more common variants include:
third condyle (condylus tertius)
basilar process
prebasioccipital arch
p...
Article
Abnormal renal rotation
Abnormal renal rotation, also known as renal malrotation, refers to an anatomical variation in the position of the kidneys, in particular to anomalous orientation of the renal hilum. It may occur unilaterally or bilaterally. It is almost always an asymptomatic incidental finding.
Epidemiology
...
Article
Intrathoracic kidney
An intrathoracic kidney is a very rare form of ectopic kidney. There has been no reported increased incidence of stones or infections as can be seen with other forms of ectopic kidneys. The adrenal glands are usually normal in location in most cases.
Epidemiology
Thoracic ectopic kidney is rar...
Article
Supraclavicular foramen
The supraclavicular foramen is a normal variant and typically found as an incidental finding on radiographs. It occurs in ~4% (range 2-6%) of the population.
Supraclavicular foramen appear as an osseous tunnel or tunnels, with the most typical position at the superior aspect of the junction of...
Article
Polyorchidism
Polyorchidism, also known as supernumerary testes, refers to the presence of more than two testes and is a very rare congenital anomaly. The supernumerary testis can be usually located inside the scrotum (75% of the patients) or less commonly in the inguinal canal, the retroperitoneum, or the ab...
Article
Superior accessory fissure
The superior accessory fissure is present in around 5% of individuals examined with CT 4 and PA chest X-rays 5.
Gross anatomy
The superior accessory fissure of the right lower lobe is located in the same plane and posterior to the right transverse (minor) fissure. It separates the right lower ...
Article
Crossed renal ectopia
Crossed renal ectopia is said to be present when the kidney is seen in the opposite retroperitoneal space. It is more common for the left kidney to be ectopically located on the right side. More than 85% of these get fused resulting in crossed fused renal ectopia. Less than 15% cases are non-fus...
Article
Duplex appendix
Duplex appendix is a rare anomaly of the appendix and is usually discovered incidentally during surgery for appendicitis.
Epidemiology
Duplication of the vermiform appendix is extremely rare. It is found in only 1 in 25,000 patients (incidence ~0.004%) operated on for acute appendicitis. Altho...
Article
Superior sublabral sulcus
A superior sublabral sulcus or superior sublabral recess is a small synovial lined gap or detachment between the labral free edge and the cartilage, forming a normal glenoid labral variant 1. It can be associated with a sublabral foramen.
Gross anatomy
The superior labral sulcus or recess is a...
Article
Retrocaval thymus
Retrocaval thymus is defined as an ectopic location of thymus between the superior vena cava and great arteries. It is a rare finding and mostly asymptomatic.
Radiographic features
Plain radiograph
may mimic mediastinal mass or right upper lobe collapse 2
CT and MRI
soft tissue that is cons...
Article
Gallbladder agenesis
Agenesis of the gallbladder describes the rare congenital absence of the gallbladder.
Epidemiology
overall incidence is estimated at <0.1% (range 0.04-0.1%)
gender:
reported 3:1 female predominance of symptomatic cases
equivalent gender distribution in autopsy cases
Associations
Gallblad...
Article
Os vesalianum pedis
An os vesalianum pedis is an accessory ossicle of the foot. Although asymptomatic, it may become symptomatic occasionally, causing lateral foot pain and requiring surgical excision 2.
Gross anatomy
It is formed as a result of failed fusion of the secondary ossification center of the metatarsal...
Article
Zuckerkandl tubercle
Zuckerkandl tubercles are the projections of normal thyroid tissue from the posterior or posteromedial margin of the thyroid gland that extend posterior to the tracheoesophageal groove. They are present in most patients and occur more commonly on the right and in the longitudinal center 50% of t...
Article
Lunula
The lunula is an accessory ossicle of the wrist. It lies in the TFCC, between the tip of the ulna styloid process and the triquetrum. It may be fused to the ulna styloid, giving it an elongated appearance.
Differential diagnosis
os triangulare: lies more radial
ulna styloid fracture
persist...
Article
Os acetabuli
Os acetabuli (plural: ossa acetabuli) are small ossicles adjacent to the acetabular roof regions and may represent an unfused secondary ossification center of the acetabulum or pathological sequelae (e.g. acetabular rim fracture, femoroacetabular impingement).
Gross anatomy
Ossa acetabuli are ...
Article
Atlanto-occipital assimilation
Atlanto-occipital assimilation is the fusion of the atlas (C1) to the occiput and is one of the transitional vertebrae.
Epidemiology
Atlanto-occipital assimilation occurs in approximately 0.5% (range 0.08-3%) of the population 2-5. It is thought to affect males and females equally.
Associati...
Article
Olecranon foramen
An olecranon foramen, also known as septal aperture or supratrochlear foramen, is a common normal anatomical variant of the distal humerus.
Epidemiology
There is a wide variation of incidence, occurring between 5% to 50% of the population depending on ethnicity, being more common in individua...
Article
Supernumerary teeth
Supernumerary teeth (hyperdontia) are teeth additional to the standard primary or permanent dentition.
Terminology
The term supplemental tooth may be used when the supernumerary tooth resembles its associated normal tooth and the term peridens may be used for an ectopically erupted (e.g. bucca...
Article
Hypodontia
Hypodontia, also known as oligodontia or adontia, refers to the developmental failure of one or more teeth, excluding the third molars.
Terminology
The phenomenon of non-development of teeth has been described using several terms including 'hypodontia', 'oligodontia' and 'adontia'. The descrip...
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