Items tagged “variant”

Patella cubiti, also known as os sesamoideum tricipitale is a very rare anomaly of the elbow, presenting as a sesamoid within the distal triceps brachii tendon. Its exact etiology is unknown with congenital, developmental and post-traumatic theories postulated 1.  Clinical presentation May be ...

Gastric diverticula are sac-like projections that usually originate from the gastric fundus, most commonly on the posterior surface. They are the least common of the gastrointestinal diverticula.  Epidemiology Gastric diverticula are rare and commonly detected incidentally. The incidence varie...

Esophageal bronchus, a.k.a. communicating bronchopulmonary foregut malformation, refers to the rare occurrence where a bronchus arises directly from the esophagus. Epidemiology It is more common in females with a M:F of 1:2 2.  Gross anatomy Esophageal bronchi may be the main bronchus, which...

Symphalangism refers to ankylosis or synostosis of the interphalangeal joints (i.e. fusion of the phalanges) in either the toes or the fingers. Less commonly, the metacarpophalangeal joints may be affected. Epidemiology One study reports symphalangism of the fifth toe in ~55% (range 40-75%) of...

Sternal foramen (or perforated sternum) is a developmental variant of the sternum and results from incomplete fusion of the sternal ossification centers. They are common, occurring in approximately 5% of the population (range 4.3-6.7%). They are most commonly found in the inferior aspect of the ...

A bipartite scaphoid is a rare example of a divided carpus. There is controversy whether this condition is congenital (i.e. normal variant) or post-traumatic. Bipartite scaphoids may be unilateral or bilateral. Diagnosis Diagnostic criteria have been proposed 3: no history of traumatic inj...

A ball and socket ankle joint is a variant affecting the ankle where there is a rounded or spherical configuration to the talar dome with the corresponding concavity of the tibial plafond. The distal fibula may or may not be involved. Pathology The etiology has been debated with two theories p...

A ring meniscus is a very rare anatomical variant of the lateral meniscus of the knee. The inner margin of a ring meniscus on coronal images can easily be mistaken for a bucket-handle meniscal tear displaced into the intercondylar space, so it is usually diagnosed during arthroscopy. 

Splenogonadal fusion is a rare anomaly that occurs when there is congenital fusion between a portion of the spleen and a gonad or other mesonephric derivative. Epidemiology Much more common in male patients (~95%), occurs most commonly on the left (98%) and usually involves the testis (95%). H...

Agenesis of the right hepatic lobe is a rare variation in liver anatomy. Radiographic features absence of the right hepatic lobe absence of right hepatic artery, right portal vein, and right hepatic biliary system compensatory hypertrophy of the left hepatic lobe and caudate lobe possible r...

Agenesis of the left hepatic lobe is a rare variation in liver anatomy. It is clinically asymptomatic and discovered during imaging or surgery. Radiographic features absence of the left hepatic lobe (left of the falciform ligament, Couinaud segments 2 and 3) absence of left hepatic artery, le...

Retrorenal spleen refers to variant position of the spleen, when its inferior portion lies posterior to the upper pole of the left kidney. This normal variant occurs in ~20% of patients, with the finding more common in patients who lie supine 1. Recognition of this variant is important to avoi...

The pyramidal lobe of thyroid (also known as Lalouette pyramid 5) is a normal anatomic variant representing a superior sliver of thyroid tissue arising from the thyroid isthmus. It is seen as a third thyroid lobe and is present in 10-30% of the population. It represents a persistent remnant of ...

Beaver tail liver, also known as a sliver of liver, is a variant of hepatic morphology where an elongated left liver lobe extends laterally to contact and often surround the anterior aspect of the spleen 2. Beaver tail liver is more common in females. The parenchyma is normal and therefore has ...

Calcaneal vascular remnant is a benign finding that may be seen on MRI of ankle and can be misinterpreted as an alarming bone lesion. It is typically located at the insertion site of sinus tarsi ligaments (cervical and interosseous ligaments). The focus of signal alteration is believed to be pr...

Incomplete double aortic arch is a rare vascular ring anomaly wherein a segment of the minor aortic arch, usually the left, is atretic.  Clinical presentation As in the case of other vascular rings, this anomaly can cause 1: stridor wheezing dysphagia Some patients may reach adulthood with...

Subvesical/subvesicular bile ducts are variants of the biliary tree, and knowledge of these is important because they account for a significant portion of post-cholecystectomy bile leaks.  Terminology Cholecystohepatic ducts (usually segment 5 to the gallbladder) are commonly known as bile duc...

The accessory soleus muscle is an anatomical variant characterized by an additional distinct muscle encountered along a normal soleus muscle. It is uncommon with a prevalence of ~3% (range 0.7-5.5%) 1. Summary origin: fibula, soleal line of the tibia, or the anterior surface of the soleus musc...

The tensor fasciae suralis muscle is an uncommon accessory muscle in the popliteal fossa. It can be an unusual cause of a popliteal fossa soft-tissue swelling or mass.  Summary origin: may arise from the distal aspect of any of the hamstring muscles, in the majority of reported cases it origin...

The paracondylar process, also known as the paraoccipital, paramastoid, parajugular or estiloid process, is a rare anatomical variant of the occipital where a bony exostosis extends caudally from the paracondylar region (lateral to the native occipital condyles), typically articulating with the ...