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.

36 results found
Article

Anaplastic lymphoma kinase (ALK) gene rearrangements

Anaplastic lymphoma kinase (ALK) gene rearrangements are known to occur in association with several tumors. The genes codes for an enzyme called anaplastic lymphoma kinase (ALK) or ALK tyrosine kinase receptor / CD246 which is thought o play a role in the brain development and exerts its effects...
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Aspergillus clavatus

Aspergillus clavatus is one of the species of Aspergillus that can cause pathology in humans. It is allergenic and causes a hypersensitivity pneumonitis called malt-workers lung. See also Aspergillus Aspergillus fumigatus Aspergillus flavus Aspergillus clavatus
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Aspiration

Aspiration occurs if liquid or solid material enters the subglottic lower respiratory tract. Terminology The term aspiration is used if material passes below the level of the vocal folds, i.e. subglottic. If material enters the larynx but remains above the vocal folds this is called penetratio...
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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. ...
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Atypical pulmonary carcinoid tumor

An atypical pulmonary carcinoid tumor is a more aggressive variant of a peripheral pulmonary carcinoid tumor. They are considered intermediate grade neoplasms and  have the same “carcinoid morphology,” but with mitotic rates increased (at 2–10 mitoses per 2 mm2) where the tumor might also be pun...
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Beryllium

Beryllium (chemical symbol Be) is an alkaline earth metallic element, that has no known function in any organism. Unfortunately beryllium is very poisonous, manifesting as chronic beryllium lung disease, which causes premature mortality in one third 1. Chemistry Basic chemistry Beryllium is a...
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Charcot-Leyden crystals

Charcot-Leyden crystals consist of collections of bipyramidal crystalloid made up of eosinophilic membrane proteins, which occur in:  asthma other eosinophilic lung disease 2 certain cases of sinusitis (e.g. allergic fungal sinusitis) They may be detected in the sputum or sinus secretions wi...
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Cyst

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....
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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

EGFR mutation

Epidermal growth factor receptor (EGFR) mutation can be expressed in a large proportion of non-small cell lung carcinomas (NSCLC). However, certain subtypes such as invasive mucinous adenocarcinoma of the lung can have very low expression. The presence of this mutation can be assessed on biopsy...
Article

Fistula

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....
Article

HER-2 mutations in lung cancer

Human epidermal growth factor receptor 2 (HER-2) mutations may be detected in approximately 3% of lung adenocarcinomas 1. Radiographic features CT Early studies have suggested HER2-mutant tumors exhibit more aggressive features in general and tend to: exhibit a locally-invasive behavior comp...
Article

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...
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Human coronavirus

The human coronaviruses (hCoVs), members of the family Coronaviridae, are enveloped RNA viruses that affect humans, mammals and birds, causing both acute and chronic illnesses. Four of the seven known human coronaviruses usually cause a mild coryzal illness only, these are HKU1, NL63, OC43, and...
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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

Lactate dehydrogenase

Lactate dehydrogenase (LDH or LD) is a key enzyme in most cells, catalyzing the reversible conversion of pyruvate to L-lactate. Its contemporaneous main clinical uses are limited primarily to the investigation of hemolysis, serous collections and as a tumor marker. Physiology L-lactate dehydro...
Article

Langerhans cell

Langerhans cells are dendritic cells of monocyte-macrophage lineage, containing large granules called Birbeck granules. They are normally found in epithelial surfaces, lymph nodes and other organs, and can also be found elsewhere, particularly in association with Langerhans cell histiocytosis. ...
Article

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...
Article

Metaplasia

Metaplasia is a general pathology term that refers to 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 replace...
Article

Mycobacterium tuberculosis

Mycobacterium tuberculosis is a thin, slightly curved bacillus. A member of the Mycobacterium tuberculosis complex, it is an obligate aerobic bacterium that is the etiologic agent of the majority of tuberculosis cases.  Epidemiology The worldwide incidence of tuberculosis was 8.7 million in 20...
Article

Oxygen

Oxygen (chemical symbol O) is one of the basic organic elements, and is a constituent of most of the known organic molecules - and therefore all lifeforms - on earth.  Chemistry Basic chemistry Oxygen is a colourless odorless diatomic gas with an atomic number 8 and atomic weight 15.999. It h...
Article

Primary lung tumors in children

Pediatric primary lung tumors are rare in children however they must be distinguished from locally aggressive inflammatory conditions and benign disease. 1 Primary lung tumors in the neonates and infants include: pleuropulmonary blastoma (PPB) infantile fibrosarcoma of the lung fetal lung in...
Article

Primary pulmonary enteric adenocarcinoma

Pulmonary enteric adenocarcinoma (PEAC) or pulmonary adenocarcinoma with enteric differentiation (PAED) is an extremely rare variant of primary invasive adenocarcinoma of the lung. It has morphological and immunohistochemical profiles overlapping with that of colorectal carcinoma. Due to this, i...
Article

Programmed death-ligand 1 (PD-L1)-targeted monoclonal antibodies

Programmed death-ligand 1 (PD-L1)-targeted monoclonal antibodies interact with a protein called PD-1 on T-cells and can be useful in determining if certain immunomodulation therapies can be used in treatment of certain types of cancers. PD-L1 is a major immune checkpoint protein that mediates an...
Article

Pseudocyst

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...
Article

Pulmonary Acinetobacter infection

Pulmonary Acinetobacter infection refers to pulmonary infection with Acinetobacter species of which Acinetobacter calcoaceticus-A baumannii complex accounts for a considerable proportion. Pulmonary infection with this organism can cause hospital acquired pneumonia (especially the late onset type...
Article

Pulmonary blastoma

Pulmonary blastomas (PBs) comprise a rare group of lung tumors principally consisting of immature mesenchymal and epithelial structures that structurally mimic the embryonic lung. Traditionally they were classified as well-differentiated fetal adenocarcinoma (WDFA) of lung - now considered rem...
Article

Pulmonary infiltrates

The term pulmonary infiltrate is considered a context-dependent, non-specific and imprecise descriptive term when used in radiology reports (plain film or CT). From a pathophysiological perspective, the term "infiltrate" refers to “an abnormal substance that accumulates gradually within cells o...
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

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

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

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

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

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

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...

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