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 continuously improved upon by countless contributing members. Our dedicated editors oversee each edit for accuracy and style. Find out more about articles.
31 results found
Article
Glucagon
Glucagon is a polypeptide hormone central to the regulation of glucose homeostasis, acting as an antagonist to insulin. In imaging, it is used as an antiperistaltic agent in GI studies, although its clinical efficacy is controversial.
Structure
Glucagon is a 29-amino acid polypeptide hormone ...
Article
Lipoma
Lipomas are benign tumors composed of mature adipocytes. They are the most common soft tissue tumor, seen in ~2% of the population.
Epidemiology
Patients typically present in adulthood (5th-7th decades).
Associations
In some cases, multiple lipomas are associated with syndromes and other di...
Article
Fecal calprotectin
Fecal calprotectin (FCAL) is a protein marker of gut inflammation. It is used as a diagnostic tool and marker of disease activity for Crohn disease and ulcerative colitis.
Biochemistry
Calprotectin is a protein complex from the S-100 family, which is formed of three polypeptide chains, two hea...
Article
Sessile
Sessile is a pathological term which is used for lesions that are attached by their base, that is they lack a stalk i.e. are not pedunculated. It is most commonly used for intraluminal polyps in the GI tract.
History and etymology
Sessile is derived from the Latin word "sessilis" which means s...
Article
Helicobacter pylori
Helicobacter pylori (H. pylori) is a gram-negative spiral flagellate microaerophilic bacterium found in the human gastric mucosa 1. It is classified as a Group I carcinogen and is considered necessary but insufficient alone to cause gastric adenocarcinoma. More often than not, it results in chro...
Article
CEA
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 ...
Article
Diverticulum
Diverticula are outpouchings of a hollow viscus and can be either true or false.
Occasionally a diverticulum is used in a more general sense to mean the outpouching of other anatomical structures, e.g. frontal intersinus septal cells are hypothesized to form as diverticula from the frontal sinu...
Article
Metaplasia
Metaplasia is a general pathology term that refers to the process when one cell type is replaced by another. It usually occurs in the context of a changed cellular environment to which the new cell type is better adapted 1.
Examples include 2-5:
Barrett esophagus: normal squamous epithelium re...
Article
Perianal genital warts
Perianal genital warts, also known as condyloma acuminata (singular: condyloma acuminatum), are a complication of human papillomavirus (HPV) infection. They are diagnosed clinically and are usually painless and benign, but can rarely undergo malignant transformation into squamous cell carcinoma....
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 ...
Article
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...
Article
Fistula
A fistula (plural: fistulae or fistulas) 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 individu...
Article
Atresia
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.
...
Article
Traditional serrated adenoma
Traditional serrated adenomas are a type of premalignant serrated colonic polyp.
Epidemiology
They are thought to account for <1% of all colonic polyps and 1-7% of all serrated lesions. They tend to occur in older patients (usually over 50 years) with no significant gender predilection.
Patho...
Article
Feces
Feces, also known as stool, is the solid component of human waste. Almost half of its dry mass is bacterial biomass, with the remainder comprised of undigested dietary matter, exfoliated cells of the gut, intestinal secretions, small metabolites and mucus.
Composition
Fecal matter is semisoli...
Article
Haggitt level
The Haggitt level is a histopathological term used for describing the degree of infiltration from a malignant polypoidal lesion.
Levels of invasion
0: carcinoma in situ or intramucosal carcinoma
1: invasion of the submucosa, but limited to the head of the polyp
2: invasion extending into the...
Article
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...
Article
Circumferential resection margin
Circumferential resection margin (CRM) is a term used to denote the standard plane of excision of total mesorectal excision, used for resection of rectal cancers. The anatomic correlate is the mesorectal fascia. The distance between tumor tissue or satellite tumor deposits and the mesorectal fas...
Article
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...
Article
Vitamin B3
Vitamin B3 (niacin or nicotinic acid) is a water-soluble vitamin, part of the vitamin B complex, that is an important part of the coenzyme nicotinamide adenine dinucleotide (NAD+) which is involved in many reactions of cellular metabolism. Vitamin B3 is one of the hematinics.
Related pathology
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