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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.

21 results found

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 th...


Amylase is widely employed as a marker of acute pancreatitis and a significant elevation is diagnostic. Physiology α-amylase is a digestive enzyme that is predominantly secreted by the acinar cells of the exocrine pancreas. It is also secreted by the salivary glands. Pancreatic amylase is enco...


Atresia (plural: atresias) refers to a situation where there is absence, underdevelopment or abnormal closure, of a normal anatomical tubular structure or opening.  Contrast this with agenesis which refers to the complete absence of any anatomical structure including its primordial precursors. ...


CA-125 is a high-molecular-weight glycoprotein found on the surface of Mullerian and coelomic epithelial-derived cell types, and is the best known tumor marker for epithelial ovarian cancer 6. Importantly, it may also be elevated in several other conditions (see differential diagnosis section be...

CA 19-9

CA 19-9 (carbohydrate antigen 19-9 or cancer antigen 19-9) is a serum antigen (monosialoganglioside) that has increased diagnostic use in the management of several malignancies, mainly of hepatopancreaticobiliary origin. It is non-specific, however, and can rise in both malignant and non-maligna...


Serum CEA (carcinoembryonic antigen) is a cell-adhesive glycoprotein that was discovered in colorectal cancer in 1965, and is hence one of the oldest and most used tumor markers. Its name derives from its normal expression in fetoembryonic liver, gut and pancreas tissue. Normal range of CEA is ...


Copper (chemical symbol Cu) is one of the trace elements. It has an important biological role as a redox agent and as a cofactor in cuproproteins, facilitating many vital metabolic reactions. Chemistry Basic chemistry Copper is a transition metal with the atomic number 29 and an atomic weight...


A cyst is an abnormal fluid-filled structure which is lined by epithelium; with one exception: lung cysts may contain gas or fluid. By contradistinction, a pseudocyst lacks an epithelial lining and instead has a vascular and fibrotic capsule. Cysts are extremely common and found in most organs....


A fistula (plural: fistulae) is an abnormal connection between two epithelial surfaces such as between hollow organs, skin or vessels. Conventionally, the name of a specific fistula type is a combination of the two organs For discussions of specific fistulae please refer to individual articles....


Hepascore is a biochemical severity scoring system based on liver function tests in predicting the extent of liver fibrosis/cirrhosis in patients with hepatitis C infection. Hepascore may also be applicable to other liver diseases and is being trialed for fatty liver disease and hepatitis B infe...

Hepatic hemangioma

Hepatic hemangiomas are most common benign vascular liver lesions. They are frequently diagnosed as an incidental finding on imaging, and most patients are asymptomatic. From a radiologic perspective, it is important to differentiate hemangiomas from hepatic malignancy.  Epidemiology Hepatic h...

Hepatoblastoma histological classification

Although hepatoblastomas can be histologically classified into a variety of subtypes, it is important to remember that with the possible exception of small cell undifferentiated subtype, prognosis is independent of histology when adjusted for stage gender and age 1. major categories epithelial...

Hernia (general)

Hernias (or herniae) are a common pathological entity, in which an anatomical structure passes into an abnormal location via an opening. The opening may be a normal physiological aperture (e.g. hiatus hernia: stomach passes through the diaphragmatic esophageal hiatus) or pathological. Iatrogeni...

KRAS mutation

KRAS (shortened name for the gene Kirsten RAt Sarcoma viral oncogene homolog) mutations are associated in a number of malignancies including:  certain adenocarcinomas of the lung colorectal carcinoma 1 pancreatic ductal adenocarcinoma Several germline KRAS mutations have also been found to b...


The term lamellated (or laminated which means the same thing) is a radiopathological term used to describe the layered appearance of many calculi, including those of the renal tract, the salivary glands, and the biliary tree. The internal structure of these calculi has been likened to that of an...


Lipase, more specifically pancreatic lipase, is an enzyme produced in the pancreas and is responsible for the digestion of fat molecules. It may be raised (hyperlipasemia) in numerous pancreatic, hepatobiliary and other diseases but is most commonly associated with acute pancreatitis. Physiolog...

Liquefactive necrosis

Liquefactive necrosis is a form of necrosis where there is transformation of the tissue into a liquid viscous mass. Pathology In liquefactive necrosis, the affected cell is completely digested by hydrolytic enzymes leading to a soft, circumscribed lesion which can consist of fluid with remains...


Macroamylasemia is the presence of serum amylase of a large molecular size, seen in both otherwise healthy individuals, and also in various diseases. Amylase seems to be able to self-polymerize and/or form complexes with other blood proteins, e.g. immunoglobulins. Epidemiology Macroamylasemia ...


Macrolipasemia is the presence of serum lipase of a large molecular size, seen occasionally in otherwise healthy individuals, but more commonly in various diseases. Lipase is able to self-polymerize and/or form complexes with other blood proteins e.g. immunoglobulins. Epidemiology Epidemiologi...


A pseudocyst is an abnormal fluid-filled cavity which is not lined by epithelium.  It is this fact that distinguishes it pathologically from a cyst, which is lined by epithelium. Examples of pseudocysts include: adrenal pseudocyst auricular pseudocyst meconium pseudocyst pancreatic pseudocy...

Serum ascites albumin gradient

The serum–ascites albumin gradient (SAAG) is the difference between the concurrently obtained serum albumin concentration and the albumin concentration of the ascitic fluid obtained during paracentesis.  Pathology A difference ≥1.1 grams/deciliter (g/dL) indicates portal hypertension as the li...

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