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 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.

244 results found
Article

Pulmonary interstitial edema

Pulmonary interstitial edema represents a form of pulmonary edema resulting from pathological fluid buildup in the interstitial spaces due to increased hydrostatic driving pressure. Pathology Interstitial lung edema arises almost exclusively due to an increase of the pulmonary capillary hydros...
Article

Red blood cell

Red blood cells (RBCs), also known as erythrocytes, are cells that carry oxygen by means of hemoglobin, and form part of the cellular component of blood as it circulates throughout the body. These extremely common cells are typically made in the bone marrow in a process called erythropoiesis. Du...
Article

Reed-Sternberg cells

Reed-Sternberg cells are a classical finding diagnostic of Hodgkin lymphoma. They are giant, multinucleated cells with abundant pale cytoplasm. Reed-Sternberg cells are rare, making up <1% of lymphoid tissue, with the background consisting of lymphocytes, plasma cells, eosinophils and macrophages.
Article

Rheumatoid factor

Rheumatoid factor (RF) is an immunoglobulin initially described in association with rheumatoid arthritis. It is an IgM antibody against the FC portion of the IgG antibodies. Ongoing research has identified a group related immunoglobulins, classed as rheumatoid factors (RFs) and despite extensive...
Article

ROS1 mutation

The ROS1 mutation is a mutation occurring in the ROS1 oncogene on chromosome 6 resulting in a defective receptor tyrosine kinase which has structural similarity to the anaplastic lymphoma kinase (ALK) protein. It is thought to be present in several cancers of the subtype non-small cell lung can...
Article

Rosenthal fibers

Rosenthal fibers are astrocytic cytoplasmic inclusions, typically found in areas of longstanding gliosis. These elongated or "corkscrew" structures occur within astrocytic processes and are brightly eosinophilic (stain bright pink on the H&E stain) 1-3. They represent astrocytic processes swolle...
Article

S100

S100 is a family of cytoplasmic calcium-binding proteins expressed in numerous cell lines which can be targeted by immunohistochemistry. Staining for S100 is helpful in characterizing a number of tumors, including malignant melanoma, glial tumors, neurogenic tumors (e.g. schwannomas and neurofib...
Article

Schiller-Duval body (histology)

Schiller-Duval body is a perivascular structure that can be found in 50% of testicular yolk sac tumors also known as endodermal sinus tumors. If present it is considered pathognomonic.  Pathology A central vessel is surrounded by tumor cells, and the cell-vessel complex is contained in a cysti...
Article

Scientific notation

In general, the Radiopaedia style guide adheres to internationally-agreed standards for scientific notation. The main exception is isotope notation, for which we have decided to drop the use of superscripted mass numbers. anatomic nomenclature chemical element notation genes and proteins nam...
Article

Selenium

Selenium (chemical symbol Se) is one of the trace elements. It has a vital role in the metabolism of the thyroid hormones and for the functioning of several important enzymes. Chemistry Basic chemistry Selenium has the atomic number 34 with an atomic weight of 78.96 g/mol. It is a non-metal a...
Article

Senile calcific scleral plaques

Senile calcific scleral plaques, also known as senile scleral plaques, are benign scleral degenerations common in elderly individuals. They are a common incidental finding on CT imaging. Epidemiology The prevalence of senile scleral plaques increases with age, from ~2.5% at age 60, to 25% at a...
Article

Sentinel lymph node

The sentinel lymph nodes (SLNs) are defined as those lymph nodes that directly drain a malignancy, or alternatively can be considered as the first node(s) that a tumor metastasizes to. History and etymology "Sentinel node" as the initial draining node of a malignancy was first used in a paper ...
Article

Septum (general)

Septa (singular: septum) are anatomical or pathological sheet-like structures that subdivide a component of normal anatomy or a lesion. Terminology Septa is the plural of the Latin word septum. Septae and septi are erroneous forms and are not words in English, nor correct plurals in Latin. Sep...
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

Starling forces

The Starling forces describe the movement of fluids between the vasculature and interstitial spaces. Fluid movement is determined by the balance of hydrostatic and osmotic pressure gradients 1. Starling forces Net pressure = [ (Pc - Pi) - (pc - pi) ] where: Pc = hydrostatic pressure of the c...
Article

Sulfur

Sulfur (chemical symbol S) is one of the essential trace elements. It has an important biological role as part of sulfur-containing amino acids and other important biochemical species such as glutathione, hydrogen sulfide, and coenzyme A. Terminology Sulfur has been the preferred spelling of t...
Article

Synaptophysin

Synaptophysin is a membrane glycoprotein found in presynaptic vesicles and is commonly used as an immunohistochemical marker for cells of neuronal (e.g. gangliogliomas) and neuroendocrine lineage (e.g. pheochromocytomas and paragangliomas) 1,2.  In the brain, it has been suggested that perisoma...
Article

Synchronous (pathology)

The term synchronous is used in oncology to refer to two (or more) independent primary malignancies, when the second (or third, etc.) malignancy arose within six months of the diagnosis of the first malignancy 1,2. These may be in the same, or in different, organs. See also metachronous multi...
Article

Synechiae

Synechiae (singular: synechia, alternative plural: synechias) are another term for adhesions, which in radiological contexts usually relates to bands of scar tissue between structures, e.g. within the abdominal cavity or pleural cavity or within the uterus. In a more narrow sense, synechia refe...
Article

Systemic pathology

The systemic pathology article aims to outline knowledge of systemic pathological conditions important for medical imaging specialists. Systemic pathology pathology of the vascular system cardiac pathology pathology of the hematological and lymphatic systems pathology of the lung and pleura...
Article

Tanycytes

Tanycytes are one of the three types of ependymal cells, themselves a type of glial cell. They are found lining the floor of the third ventricle overlying the median eminence of the hypothalamus 1.   It is believed that these specialized cells are involved in the feedback mechanisms on the ante...
Article

TDP-43 proteinopathy

The TDP-43 proteinopathies are a set of neurodegenerative disorders characterized pathologically by cytoplasmic inclusions composed of TDP-43. The pathology has been implicated in three major diseases: amyotrophic lateral sclerosis (vast majority of cases) frontotemporal lobar degeneration (sl...
Article

Thyroid transcription factor 1

Thyroid transcription factor 1 (TTF1) refers to a homeodomain-containing nuclear transcription factor which belongs to the Nkx2 gene family encoded by a gene located on chromosome 14q13. It is expressed in the forebrain, thyroid and lung tissues. The presence of TTF-1 protein on a tissue sample...
Article

Thyroseq

Thyroseq® is an expanded gene classifier test designed for further evaluation of indeterminate thyroid nodules on fine needle aspiration (FNA). In particular, it is designed to further evaluate nodules that show atypia of undetermined significance/follicular lesion of undetermined significance (...
Article

Tissue tropism

Tissue tropism is a phenomenon by which certain host tissues preferentially support the growth and proliferation of pathogens. This concept is central to the radiological evaluation of infectious disease.  Pathology As infections that display tissue tropism will thrive in certain tissue locati...
Article

TP53 (gene)

The TP53 gene, located on chromosome 17, is a tumor suppressor gene, responsible for the production of the p53 protein, a transcription regulatory protein which works in concert with a number of other proteins, together forming the p53 pathway 1,2. Inherited mutations in this gene result in the...
Article

Trace elements

The trace elements are chemical elements which are essential - but only in tiny quantities - for optimal physical and mental well being. The elements are: cobalt copper iodine iron manganese molybdenum selenium sulfur zinc It is now contentious whether chromium is a truly essential tra...
Article

Transitional meningioma

Transitional meningiomas are also known as mixed meningiomas because they have components of meningothelial and fibrous subtypes of meningiomas. Their epidemiology, clinical aspects, radiographic characteristics, treatment, prognosis, and differential diagnosis are in the main article (see meni...
Article

Tuberculous abscess

Tuberculous abscesses are an uncommon presentation of tuberculosis, most often encountered in immunocompromised individuals (e.g. HIV/AIDS). Unlike the far more common tuberculomas (tuberculous granulomas), tuberculous abscesses contain pus with abundant identifiable organisms 1. The capsule tha...
Article

Tumor markers

Tumor markers are a group of molecules in serum that are elevated in various malignancies and are often used to monitor treatment response as well as alert for potential progressive disease when in remission. Commonly used markers include: AFP (alpha fetoprotein) beta-hCG CA 15-3 CA 19-9 C...
Article

Tumor spread through air spaces

Tumor spread through air spaces (STAS) is a relatively recently recognized pattern of invasion in lung adenocarcinoma. According to the 2015 WHO classification, STAS is defined as “micropapillary clusters, solid nests, or single cells spreading within air spaces beyond the edge of the main tumor...
Article

Urine

Urine represents the biofluid end-product of the renal filtration process. Normally it is a transparent, sterile, pale-yellow liquid (although clearly color varies with the person's hydration status).  Urine is one of the most easily-accessible biofluids in the human body and has been intensive...
Article

Vascular invasion in lung cancer

Vascular invasion in lung cancer is one of the invasive patterns that can occur in lung cancer. Dependent on the publication, this could mean: intratumoral vascular invasion (IVI)  microscopic vascular invasion (MVI) lymphovascular invasion (LVI) lymphatic permeation arterial invasion veno...
Article

Vector (infectious disease)

A vector, (also known as a biological vector) in the context of infectious diseases, is a carrier, in particular an animal, and most commonly an arthropod, that transmits the infective entity from one host to another 1. Often the infective agent undergoes some change as part of its normal life c...
Article

Verocay bodies

Verocay bodies are a histological feature of schwannomas and represent a particular growth pattern of Antoni type A pattern in which tumor cells form alternating parallel rows of nuclear palisades separated by regions of acellularity 1. 
Article

Vimentin

Vimentin is a fairly widespread cytoskeletal component encoding for intermediate filaments. It can be used as a target for immunohistochemistry to help characterize numerous tissues and tumors. 
Article

Vitamin A

Vitamin A are a group of fat-soluble vitamers (the retinoids) required for many physiological functions, mainly vision, reproduction and epithelial maintenance. In the retina, a specific retinoid, 11-cis-retinal, is formed by photoisomerisation within the rods and cones. Related pathology Path...
Article

Vitamin B1

Vitamin B1 (thiamine) is a water-soluble vitamin, that is part of the vitamin B complex, and is an important coenzyme for two reactions in the citric acid cycle (Kreb cycle). It therefore is vital for cellular ATP production, particularly in the central nervous system. Terminology Thiamine is ...
Article

Vitamin B12

Vitamin B12 (hydroxocobalamin, hydroxycobalamin or B12a) is a water-soluble vitamin, part of the vitamin B complex, and synthesized by intestinal flora that forms a cobalt-based coenzyme that is required for two vital cellular reactions, namely the production of methionine (an amino acid) and th...
Article

Vitamin B2

Vitamin B2 (riboflavin) is a water-soluble vitamin, part of the vitamin B complex, that is an important component of the cofactors flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). The flavoproteins contribute to many cellular reactions, including the metabolism of several other...
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. Related pathology pellagra is the clinical syndrome of...
Article

Vitamin B5

Vitamin B5 (pantothenic acid) is a water-soluble vitamin, part of the vitamin B complex, that is required to synthesize coenzyme A, a very important coenzyme in many cellular metabolic reactions.Vitamin B5 deficiency (hypovitaminosis B5) is extremely rare. There is no evidence of any deleteriou...
Article

Vitamin B6

Vitamin B6 is a group of water-soluble vitamins, part of the vitamin B complex, and that are derivatives of pyridine, the main vitamers are known as pyridoxine, pyridoxal and pyridoxamine. All three form part of the coenzyme pyridoxal 5'-phosphate (PLP) which is involved in many cellular reactio...
Article

Vitamin B9

Vitamin B9 (folate or folic acid) is a water-soluble vitamin, part of the vitamin B complex, vital for the synthesis of several amino acids, the purines adenosine and guanine and the pyrimidine thymine (three of the four nucleotide bases and hence critical for the synthesis of nucleic acids). T...
Article

Vitamin B complex

Historically, the vitamin B complex was the collective name given to a specific subset of the vitamins, known as the B vitamins. However the chemical structures of these compounds are structurally heterogeneous and they do not constitute a distinct biochemical group. They are all water soluble v...
Article

Vitamin C

Vitamin C (ascorbic acid) is a water soluble vitamin that is a coenzyme for the formation of the structure protein collagen, particularly creating cross-linking of collagen fibers which greatly increases its tensile strength. It also acts as an antioxidant. History and etymology Vitamin C was ...
Article

Vitamin D

Vitamin D (calciferol) is used to describe a group of five fat-soluble secosteroid vitamins required for the homeostasis of serum calcium and phosphorus. Vitamin D exists in two main forms (vitamers) in humans: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).  Vitamin D3 acts by re...
Article

Vitamin D deficiency (overview)

Vitamin D deficiency (also known as hypovitaminosis D) is common, and untreated, may result in serious sequelae. Traditionally its pathological manifestations have been regarded through the lens of skeletal maturity: rickets in children osteomalacia in adults However it has become increasingl...
Article

Vitamin E

Vitamin E (the tocopherols) are a group of fat-soluble vitamins that act as antioxidants. hypovitaminosis E is rarely seen outside premature infants hypervitaminosis E is extremely rare as the toxicity of vitamin E is low except in chronic (usually >1 year) high doses. The commonest sequela is...
Article

Vitamin K

Vitamin K is not a single compound but a family of fat-soluble vitamins essential for normal blood-clotting function and comprises two vitamers that are found naturally: phytomenadione (also known as phylloquinone or K1) and menaquinone (or K2). Menaquinone (K2) is synthesized by normal flora i...
Article

Vitamins

Vitamins are a group of organic compounds used in biochemical pathways. Many are components of coenzymes in particular metabolic reactions. Vitamins are generally not synthesized by the human body and hence must be acquired through the diet. Vitamer is the name given to the different forms of a ...
Article

Vulnerable plaque

Vulnerable or high-risk plaque refers to coronary artery atherosclerotic lesions with features associated with future acute coronary events, independent of luminal stenosis. Clinical presentation The relevant clinical sequelae of vulnerable plaque are acute coronary syndromes, which present as...
Article

Well differentiated fetal adenocarcinoma of lung

A well-differentiated fetal adenocarcinoma (WDFA) of lung is a rare low grade lung tumor. Some consider this as a variant of adenocarcinoma with others considering this under the group of pulmonary blastomas 5.  According to classification by the World Health Organization in 1999, it was remove...
Article

White blood cell

White blood cells or leukocytes are one of the main cell types found in normal human blood. They are actually colourless (but appear white on light microscopy) and divided into granular and non-granular types. Types of white blood cell: granular neutrophils eosinophils basophils non-granul...
Article

WHO classification of eye tumors

The World Health Organization (WHO) classification of eye tumors is a widely used pathologic classification system of neoplasms of the orbit. The current revision, part of the 4th edition of the WHO series, was published in 2018 and is reflected in the article below 1. Classification Tumors of...
Article

WHO histological classification of tumors of the uterine cervix

The WHO histological classification is a detailed classification of tumors of the uterine cervix. epithelial tumors squamous tumors and precursors squamous cell carcinoma, not otherwise specified - 8070/3 keratinizing - 8071/3 non-keratinizing - 8072/3 basaloid - 8083/3 verrucous - 8051/3...
Article

Zinc

Zinc (chemical symbol Zn) is a trace element with a key role as a constituent of enzymes, e.g. carbonic anhydrase, and as part of zinc finger proteins, vital for the correct folding of macromolecules, such as DNA. More recently zinc has been found to act as an important cellular messenger 3. Ch...
Article

Zoonosis

A zoonosis (plural: zoonoses), also known as a zoonotic disease, is an infectious disease in humans (the host) for which another vertebrate animal can be the vector. Some zoonoses have an additional vector besides the vertebrate e.g. R. rickettsii is carried by ticks on mammals. Viruses, bacteri...

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.