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1,933 results found

Achalasia

Achalasia (primary achalasia) is a failure of organized esophageal peristalsis causing impaired relaxation of the lower esophageal sphincter, and resulting in food stasis and often marked dilatation of the esophagus. Obstruction of the distal esophagus from other non-functional etiologies, not...

Tertiary esophageal contractions

Tertiary esophageal contractions are a type of contractions of the esophagus often described as as the irregular contraction or indentations of the distal esophageal wall. Isolated tertiary esophageal waves of the non-repetitive type are thought to occur in normal subjects. Swallowing induced re...

Thymic epithelial tumors

Thymic epithelial tumors are rare tumors arising from thymus in anterior mediastinum of middle age patients, these tumors encompass thymomas, invasive thymomas and thymic carcinoma. Despite their relative rarity, they are the most common primary neoplasm of the thymus and anterosuperior mediasti...

Miliary opacities (lungs)

The term miliary opacities refers to innumerable, small 1-4 mm pulmonary nodules scattered throughout the lungs. It is useful to divide these patients into those who are febrile and those who are not. Additionally, some miliary opacities are very dense, narrowing the differential - see multiple...

Lung volume reduction surgery

Lung volume reduction surgery (LVRS) is an emerging promising palliative treatment option for select patients with severe, debilitating pulmonary emphysema. It usually involves bilateral wedge resection of 20-30% of the most diseased lung through a median sternotomy. It has been proposed that L...

Air trapping

Air trapping in chest imaging refers to retention of excess gas (“air”) in all or part of the lung, especially during expiration, either as a result of complete or partial airway obstruction or as a result of local abnormalities in pulmonary compliance. It may also sometimes be observed in norma...

Nodular pulmonary amyloidosis

Nodular pulmonary amyloidosis is a subtype of pulmonary amyloidosis. It is considered a limited form of amyloidosis characterized by one or more pulmonary nodules or masses (amyloidomas). Epidemiology Albeit rare in general, the nodular form is more common than the diffuse parenchymal form. Th...

Congenital pulmonary airway malformation

Congenital pulmonary airway malformations (CPAM) are multicystic masses of segmental lung tissue with abnormal bronchial proliferation. CPAMs are considered part of the spectrum of bronchopulmonary foregut malformations. Terminology Until recently, they were described as congenital cystic aden...

Thymus

The thymus (plural: thymi) is a T-cell producing lymphoid organ in the anterior mediastinum that plays a role in the development of the immune system particularly, maturation of T-cells. It typically has a retrosternal location and hence may mimic retrosternal pathology. Gross anatomy It is re...

Asthma

Asthma is a relatively common condition that is characterized by at least partially reversible inflammation of the airways and reversible airway obstruction due to airway hyperreactivity. It can be acute, subacute or chronic. Epidemiology Asthma is one of the most common chronic diseases in th...

Fibrotic hypersensitivity pneumonitis

Fibrotic hypersensitivity pneumonitis (fHP) is a chronic, often progressive fibrosing form of hypersensitivity pneumonitis and is also often categorized as a form of interstitial lung disease. Manifestations previously categorized as chronic hypersensitivity pneumonitis now fall under this categ...

Tree-in-bud sign (lung)

Tree-in-bud sign or pattern describes the CT appearance of multiple areas of centrilobular nodules with a linear branching pattern. Although initially described in patients with endobronchial tuberculosis, it is now recognized in a large number of conditions. Pathology Pathogenesis Simply put...

Azygos vein

The azygos vein is a unilateral vessel that ascends in the thorax to the right of the vertebral column, carrying deoxygenated blood from the posterior chest and abdominal walls. It forms part of the azygos venous system. Terminology The spelling azygous when referring to the vein is incorrect,...

Tracheal buckling

Tracheal buckling is a normal finding in young infants when the trachea is more flexible. There is typically deviation of the trachea anteriorly and to the right (up to 90°). Normal deviation to the left is observed only when aortic arch is locate to the right of the trachea 4. Any other configu...

CT pulmonary angiogram (protocol)

The computed tomography pulmonary angiogram (CTPA/CTPE) is a commonly performed diagnostic examination to exclude pulmonary emboli (PE). Each radiology department will have a slightly different method for achieving the same outcome, i.e. diagnostic density of the main pulmonary artery and its br...

Pulmonary embolism

Pulmonary embolism (PE) refers to embolic occlusion of the pulmonary arterial system. The majority of cases result from thrombotic occlusion, and therefore the condition is frequently termed pulmonary thromboembolism, which is what this article mainly covers. Non-thrombotic pulmonary emboli sou...

Medical devices in the thorax

Medical devices in the thorax are regularly observed by radiologists when reviewing radiographs and CT scans. Extrathoracic devices tubing, clamps, syringes, scissors, lying on or under the patient rubber sheets, foam mattresses, clothing, hair braids, nipple piercings, etc., may also be visi...

COVID-19

For a quick reference guide, please see our COVID-19 summary article. COVID-19 (coronavirus disease-2019) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a strain of coronavirus. The first cases were seen in Wuhan, China, in December 2019 before ...

Inferior accessory fissure of the lung

The inferior accessory fissure of the lung, also known as Twining's line, divides the medial basal bronchopulmonary segment from the rest of the lower lobe. Epidemiology This accessory fissure is present in around 12% of people when examined with CT and is visible on 5-8% of frontal chest x-ra...

Multisystemic smooth muscle dysfunction syndrome

Multisystemic smooth muscle dysfunction syndrome is a rare genetic disorder caused by mutations in the ACTA2 gene, resulting in intracranial steno-occlusive disease and aortic dissection or aneurysm, among other complications. Epidemiology Most cases are diagnosed in childhood 1. Clinical pre...

Pulmonary Pneumocystis jiroveci infection

Pulmonary Pneumocystis jiroveci infection, also known as Pneumocystis jiroveci pneumonia (PJP) or Pneumocystis pneumonia (PCP), is an atypical pulmonary infection and the most common opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS). Terminology Classically, "P...

Histoplasmosis

Histoplasmosis is an endemic mycosis caused by Histoplasma capsulatum. Pulmonary histoplasmosis is the most common manifestation of this infectious disease. Disseminated histoplasmosis is often seen in immunosuppressed patients. As such, these are included among the infectious etiologies of AI...

Airway foreign bodies in children

Airway foreign bodies in children are potentially fatal, which is why immediate recognition is important. Unfortunately, delayed diagnosis is common. Epidemiology Children under the age of four years are at increased risk of foreign body (FB) aspiration, with a slight male predominance 1. Cl...

Posttransplant lymphoproliferative disorder

Post-transplant lymphoproliferative disorder (PTLD), also referred as post-transplant lymphoproliferation disorder, represents a variety of conditions ranging from lymphoid hyperplasia to malignancy, included in the WHO classification of tumors of hematopoietic and lymphoid tissues. It can be a ...

Disseminated histoplasmosis

Disseminated histoplasmosis, also known as progressive disseminated histoplasmosis, is a severe form of histoplasmosis infection typically seen in immunosuppressed patients, especially in the setting of HIV infection. It results from hematogenous dissemination of the infection, involving multipl...

Thoracic histoplasmosis

Thoracic (or pulmonary) histoplasmosis refers to pulmonary manifestations from infection with the fungus Histoplasma capsulatum which is an organism endemic to the Central American state of El Salvador but can be found widely in other parts of both North and South America. It can have variable c...

Extrapleural fat

Extrapleural fat is a benign condition and refers to relative diffuse deposition of fat outside the parietal pleura. It can occur in various locations but typically occurs along the chest wall. It is a component of the loose connective tissue of the endothoracic fascia and is most abundant along...

Bochdalek hernia

Bochdalek hernias , also known as pleuroperitoneal hernias, (alternative plural: herniae) are the commonest type of congenital diaphragmatic hernia. They occur posteriorly and are due to a defect in the posterior attachment of the diaphragm when there is a failure of pleuroperitoneal membrane cl...

Innominate artery compression syndrome

Innominate artery compression syndrome, also known as brachiocephalic artery compression syndrome, is a rare cause of tracheal stenosis that occurs in the pediatric population. It is due to abnormal compression of the anterior aspect of the trachea as the brachiocephalic artery crosses it. Diag...

Lipoid pneumonia

Lipoid pneumonia is a form of pneumonia associated with oily or lipid components within the pneumonitis component. This can either result from: aspiration of oily substances (exogenous lipoid pneumonia) or endogenous accumulation of lipid substances in the alveoli (endogenous lipoid pneumonia...

Valsalva maneuver

The Valsalva maneuver is the forced expiration of air against a closed airway, resulting in increased intra-abdominal, intrathoracic, and pharyngeal pressure. It can be performed against a closed glottis or by one closing the mouth and pinching the nose while forcibly exhaling. It is commonly u...

Differential diagnosis for a small cardiothoracic ratio

A small cardiothoracic ratio (CTR) is defined as <42%/0.42 when assessed on a PA chest radiograph, and is often called small heart syndrome. A pathologically-small heart is also known as microcardia. It can be due to/associated with a number of entities: adrenal insufficiency, e.g. Addison...

Pulmonary pseudotumor

A pulmonary pseudotumor is no more than 'something' which mimics a tumor. Most frequently it is caused by a loculated pleural effusion (pleural pseudotumor) trapped in the pleural fissures. Other entities which have been described with the term pseudotumors include: round atelectasis p...

Minimally invasive adenocarcinoma of the lung

Minimally invasive adenocarcinoma (MIA) of the lung is a relatively new category in the classification of adenocarcinoma of the lung. Lesions that fall into this category refer to small solitary adenocarcinomas <3 cm (i.e. <30 mm) with either pure lepidic growth or predominant lepidic growth wit...

Lepidic-predominant adenocarcinoma of the lung

Lepidic-predominant adenocarcinoma (LPA) of the lung, formerly known as non-mucinous bronchoalveolar carcinoma, is a subtype of invasive adenocarcinoma of the lung characterized histologically when the lepidic component comprises the majority of the lesion. Terminology The category of "lepidic...

Pulmonary gangrene

Pulmonary gangrene can be a complication of necrotizing pneumonia and often represents a final stage in a continuum of progressive devitalisation of pulmonary parenchyma and is characterized by sloughing of a pulmonary segment or lobe. Pathology In most instances, it occurs as a complication o...

Crescent sign (disambiguation)

The characteristic shape of the crescent has been given to many radiological signs over the years: air crescent sign (aspergillosis) crescent in a doughnut sign (intussusception) crescent sign (arterial dissection) crescent sign (intravenous pyelogram) crescent sign (lung hydatid) crescent...

Scimitar syndrome

Scimitar syndrome, also known as hypogenetic lung syndrome, is characterized by a hypoplastic lung that is drained by an anomalous pulmonary vein into the systemic venous system. It is a type of partial anomalous pulmonary venous return and is one of the several findings in congenital pulmonary ...

Unilateral pulmonary artery atresia

Unilateral pulmonary artery atresia (UPAA), also known as unilateral absence of the pulmonary artery (UAPA) or proximal interruption of the pulmonary artery, is a variant of pulmonary artery atresia. Terminology The term interruption is preferred by some to absence or atresia because the anom...

Right upper lobe consolidation

Right upper lobe consolidation refers to consolidation in part (incomplete) or all (complete) of the right upper lobe. Pathology Consolidation refers to the alveolar airspaces being filled with fluid (exudate/transudate/blood), cells (inflammatory), tissue, or other material. The list of caus...

Mediastinal lymphoma

Mediastinal lymphoma is common, either as part of disseminated disease or less commonly as the site of primary involvement. Epidemiology Lymphomas are responsible for approximately 15% of all primary mediastinal masses, and 45% of anterior mediastinal masses in children 1. Only 10% of lympho...

Esophagopleural fistula

Esophagopleural fistulas are abnormal connections between the esophagus and pleura. Pathology They can arise from a number of underlying pathologies which can result in an esophageal rupture 3: post surgical endoscopic procedures post esophageal dilatation secondary to tumor, e.g. esophag...

Foregut duplication cyst

Foregut duplication cysts are a type of congenital duplication cyst. They are sometimes classified under bronchopulmonary foregut malformations. Entities classified as foregut duplication cysts include: bronchogenic cysts neurenteric cysts other enteric cysts esophageal duplication...

Fluoroscopic evaluation of esophagectomy

Fluoroscopic evaluation of esophagectomy is an important study, given the high rate of complication following esophagectomy (~10-20% rate of leak). Although the approach will differ slightly depending on the type of esophagectomy performed, the principles are similar. Procedure Preprocedural e...

Small airways disease

Small airways disease comprise of a group infectious as well as non-infectious conditions that affect the small airways (i.e. airways that are more peripheral to the main bronchi and proximal bronchioles (4th the 14th generation) - arbitrarily considered to be those with an internal diameter of ...

Diaphragmatic slips

Diaphragmatic slips are the muscular bundles that attach the central tendon of the diaphragm to the inside of the bones and cartilage of the lower 6-7 ribs, xiphoid process, lumbar vertebrae 1. They can mimic or help identify pathology when seen on imaging modalities. Mimics Diaphragmatic slip...

Lymphoid interstitial pneumonia

Lymphoid interstitial pneumonia (LIP), also known as lymphocytic interstitial pneumonitis, is a benign lymphoproliferative disorder characterized by lymphocyte predominant infiltration of the lungs. It is classified as a subtype of interstitial lung disease. It also falls under the umbrella of n...

Aortic intramural hematoma

Aortic intramural hematoma is an atypical form of aortic dissection due to a contained hemorrhage into the aortic wall usually from the vasa vasorum without an intimal tear. It forms part of the acute aortic syndrome spectrum along with penetrating atherosclerotic ulcer and classical aortic diss...

Thymus protocol (MRI)

Thymic MRI is a targeted mediastinal imaging protocol performed mainly to distinguish surgical from nonsurgical thymic lesions (eg. thymic hyperplasia, thymic cysts, and lymphoma). Note: This article is intended to outline some general principles of protocol design. The specifics will vary depe...

Diaphragm

The diaphragm is the dome-shaped skeletal muscle that separates the thoracic cavity from the abdominal cavity, enclosing the inferior thoracic aperture. Terminology On chest imaging, in particular chest radiography, an imaginary anteroposterior halfway line divides the diaphragm into two, form...

Bronchial artery

The bronchial arteries are the major supply of high-pressure oxygenated blood to the supporting structures of the lung, including the pulmonary arteries, but contribute only 1% of total lung blood flow. Blood in the bronchial circulation does not take part in gas exchange unless there is patholo...

Esophagus

The esophagus (plural: esophagi or esophaguses) is a muscular tube that conveys food and fluids from the pharynx to the stomach. It forms part of the upper gastrointestinal tract. Gross anatomy The esophagus is 23-37 cm long with a diameter of 1-2 cm and is divided into three parts: cervical:...

Aortic hiatus

The aortic hiatus is one of the three major apertures through the diaphragm and lies at the level of T12. Strictly speaking, it is not a real aperture in the diaphragm, but an osseoaponeurotic opening between it and the vertebral column. The hiatus is situated slightly to the left of the midli...

Rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune multisystemic inflammatory disease that affects many organs but predominantly attacks the synovial tissues and joints. Epidemiology The overall prevalence is 0.5-1% and the disease is 2-3 times more common in women 1. Onset is generally in adu...

Aberrant right subclavian artery

Aberrant right subclavian arteries (ARSA), also known as arteria lusoria, are among the commonest aortic arch anomalies. Epidemiology The estimated incidence is 0.5-2% 1. Associations as can be expected from the embryological development of the artery, the right recurrent laryngeal nerve...

V/Q scan

V/Q (ventilation/perfusion) scan is a scintigraphic examination of the lung that evaluates pulmonary vasculature perfusion and segmental bronchoalveolar tree ventilation. Indications diagnosis of suspected pulmonary embolism monitor pulmonary function following lung transplant pro...

Paratracheal air cyst

Paratracheal air cysts are not an uncommon incidental finding in routine thoracic imaging. They characteristically occur on the right side, in the region of the thoracic outlet. Occasionally it may mimic pneumomediastinum, so-called pseudopneumomediastinum. Terminology Paratracheal air cysts e...

Primary effusion lymphoma

Primary effusion lymphoma is a rare form of non-Hodgkin lymphoma (diffuse large B-cell lymphoma) characterized by malignant fluid accumulation in the absence of lymphadenopathy. Epidemiology Associations immunodeficiency states such as acquired immunodeficiency syndrome (AIDS) infections inc...

Hypogammaglobulinaemia

Hypogammaglobulinaemia is an immune disorder characterized by a reduction in all types of gammaglobulins. Terminology While hypogammaglobulinaemia means some loss of gammaglobulins, a total loss is termed agammaglobulinaemia which can occur as an X-linked form (X-linked agammaglobulinemia). ...

Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a rare multisystem disease with a wide and heterogeneous clinical spectrum and variable extent of involvement. Terminology Langerhans cell histiocytosis was previously known as histiocytosis X. The newer term is preferred as it is more descriptive of its...

Acute interstitial pneumonitis

Acute interstitial pneumonitis (AIP), also known as Hamman-Rich syndrome, is a rapidly progressive non-infectious interstitial lung disease of unknown etiology. It is considered the only acute process among the idiopathic interstitial pneumonias. Terminology AIP has a similar clinical present...

Diffuse alveolar damage

Diffuse alveolar damage (DAD) is a common manifestation of drug-induced lung injury that results from necrosis of type II pneumocytes and alveolar endothelial cells. Clinical presentation Affected patients present with dyspnea, cough, and occasionally fever. The diffusion capacity of the lung ...

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a form of acute lung injury and occurs as a result of a severe pulmonary injury that causes alveolar damage heterogeneously throughout the lung. It can either result from a direct pulmonary source or as a response to systemic injury. This is a disti...

AIDS-defining illness

AIDS-defining illnesses are conditions that in the setting of a HIV infection confirm the diagnosis of AIDS and do not commonly occur in immunocompetent individuals 2. According to the CDC surveillance case definition 1, they are: Infectious bacterial infections: multiple or recurrent ca...

Castleman disease

Castleman disease, also known as angiofollicular lymph node hyperplasia or giant lymph node hyperplasia, is an uncommon benign B-cell lymphoproliferative condition. It can affect several regions of the body but is commonly described as a solitary mediastinal mass. There are two distinct subtype...

Solitary fibrous tumor of the pleura

Solitary fibrous tumors of the pleura are rare benign pleural-based tumors that account for <5% of all tumors involving the pleura. Terminology Throughout much of the twentieth century, there was a continual debate about the precise histology of both normal pleura and pleural tumors. The prope...

Tracheomalacia

Tracheomalacia, or sometimes described as tracheobronchomalacia, is a common incidental finding on imaging of the chest of older patients and manifests as an increase in tracheal diameter as well as a tendency to collapse on expiration. Tracheomalacia can be broadly considered as being congenit...

Garland triad

Garland triad, also known as the 1-2-3 sign or pawnbroker's sign, is a lymph node enlargement pattern on chest radiographs which has been described in sarcoidosis: right paratracheal nodes right hilar nodes left hilar nodes Hilar lymphadenopathy is symmetrical and usually massive...

Non-expandable lung

Non-expandable lung results from failure of the lung to re-expand even despite a therapeutic measure such as insertion of a chest tube. This can include two semantically similar but slightly different terms: trapped lung: non-expandable lung due to remote / prior pleural inflammation lung entr...

Fibrosing mediastinitis

Fibrosing mediastinitis is a rare non-malignant acellular collagen and fibrous tissue proliferative condition occurring within the mediastinum. On imaging, the condition can sometimes mimic malignancy. Epidemiology Although it can potentially present at any age, it typically presents in young ...

Squamous cell carcinoma of the lung

Squamous cell carcinoma (SCC) is one of the non-small cell carcinomas of the lung, second only to adenocarcinoma of the lung as the most commonly encountered lung cancer. Epidemiology Squamous cell carcinoma accounts for ~30-35% of all lung cancers and in most instances is due to heavy smokin...

Nuss procedure

The Nuss procedure (also termed MIRPE - minimally invasive repair of pectus excavatum) is one of the operative treatments employed in patients with pectus excavatum. It involves the insertion of one (or more) concave metal bars beneath the sternum in the anterior chest wall. It is significantly...

Haller index

The Haller index (HI), also known as the pectus index, is a simple mathematical way to assess and describe the chest cage on CT of the thorax and is used in the detection and pre/postoperative assessment of pectus excavatum 1,5. Measurement The Haller index is calculated by dividing the transv...

Pectus excavatum

Pectus excavatum, also known as funnel chest or trichterbrust 13, is a congenital chest wall deformity characterized by concave depression of the sternum, resulting in cosmetic and radiographic alterations. Epidemiology It is the most common chest wall deformity, accounting for approximately 9...

Tracheal and endobronchial lesions

Primary tracheal and endobronchial lesions are generally rare and can be either malignant or benign. The majority of these lesions are malignant. Pathology Malignant primary malignant endobronchial lesions bronchogenic adenocarcinoma squamous cell carcinoma: commonest malignant lesion in th...

Lung entrapment

Lung entrapment is a type of unexpandable lung and typically refers to lung tissue enclosed by active pleural inflammation or pleural tumor1. The thickened visceral pleura prevents full expansion of the lung and the diaphragm may be displaced affecting its function; both of these can cause dyspn...

Trapped lung

Trapped lung is a type of unexpandable lung, and the term is used when a thick, fibrotic visceral pleural rind prevents lung expansion. This is commonly post-pneumonic, occurring when active pleural inflammation heals with fibrosis. This differs from the situation of actively inflamed and thicke...

Pancoast tumor

Pancoast tumor, also known as superior sulcus tumor, refers to a relatively uncommon situation where a primary lung cancer arises in the lung apex and invades the surrounding soft tissues. Classically a Pancoast syndrome results, but in actuality this is only seen in one quarter of cases. Term...

Apical pleural cap

Apical pleural cap refers to a curved density at the lung apex seen on chest radiographs. Epidemiology The frequency of apical pleural thickening increases with age 3. There may be a slightly greater male predilection 7. Pathology It arises from a number of causes: pleural thickening/...

Psammoma bodies

Psammoma bodies are round microscopic calcific collections. It is a form of dystrophic calcification. Necrotic cells form the focus for surrounding calcific deposition. They have a lamellated concentric calcified structure, sometimes large enough to be seen on CT. Psammoma bodies are found in ...

Pulmonary arteriovenous malformation

Pulmonary arteriovenous malformations (PAVMs) are rare vascular anomalies of the lung, in which abnormally dilated vessels provide a right-to-left shunt between the pulmonary artery and vein. They are generally considered direct high flow, low-resistance fistulous connections between the pulmona...

Carcinoid tumors of the lung

Carcinoid tumors of the lung are a subgroup of neuroendocrine tumors of the lung, of lower grade than small cell carcinoma of the lung and large cell neuroendocrine carcinoma of the lung. For a general discussion, please refer to the article on carcinoid tumors. Pathology Classification Car...

Arterial thoracic outlet syndrome

Arterial thoracic outlet syndrome (aTOS) is considered rarest from of thoracic outlet syndrome and can result in compression of arterial structures (especially the subclavian artery) at thoracic outlet, or superior thoracic aperture. Many of these patients may also have concurrent venous thora...

Bovine arch

Bovine arch is the most common variant of the aortic arch and occurs when the brachiocephalic (innominate) artery shares a common origin with the left common carotid artery. Epidemiology A bovine arch is present in ~15% (range 8-25%) of the population and is more common in individuals of Afri...

Paget-Schrötter syndrome

Paget-Schrötter syndrome, alternatively spelled Paget-Schroetter syndrome and also known as effort thrombosis, refers to primary thrombosis of the axillary and/or subclavian vein. It can be thought of as a venous equivalent of thoracic outlet syndrome (i.e. venous thoracic outlet syndrome). Epi...

Venous thoracic outlet syndrome

The venous thoracic outlet syndrome (vTOS) is the second commonest form of thoracic outlet syndrome (with neurogenic thoracic outlet syndrome being the commonest and the arterial thoracic outlet syndrome being the least common). Clinical presentation It may develop suddenly, often after unusua...

Thoracic outlet syndrome

Thoracic outlet syndrome refers to a group of clinical syndromes caused by congenital or acquired compression of the brachial plexus or subclavian vessels as they pass through the superior thoracic aperture 11. Clinical presentation Clinical presentation will depend on the structure compresse...

Signet ring (disambiguation)

The term signet ring refers to the characteristic shape of the jewelry item and in radiology and medicine may refer to the following: signet ring sign (bronchiectasis) signet ring sign (scaphoid) signet ring cells in adenocarcinoma histology such as in the rectum, appendix and ovary (Krukenbe...

Head cheese sign (lungs)

The head cheese sign (more recently termed the three-density pattern refers to a juxtaposition of regions with three (or sometimes more) different densities/regions of different attenuation within the lungs: ground-glass opacities (high attenuation) mosaic attenuation pattern (low attenuation)...

Croup

Croup, also known as acute laryngotracheobronchitis, is due to viral infection of the upper airway by parainfluenza virus or respiratory syncytial virus (RSV). Although imaging findings are not required for the diagnosis, classic findings of narrowing of the subglottic airway and dilatation of ...

Steeple sign (trachea)

The steeple sign (also called the wine bottle sign, and inverted V sign), refers to the tapering of the upper trachea on a frontal chest radiograph reminiscent of a church steeple, suggestive of croup. A corresponding lateral x-ray would show narrowing of the subglottic trachea and ballooning of...

Cysts of Hattori

Cysts of Hattori, also known as posterior mediastinal paravertebral Müllerian cysts, are mediastinal cysts of Mullerian origin, lined by ciliated non-stratified cuboidal to columnar epithelium, that occur in the posterior mediastinum. Epidemiology Of all mediastinal masses, ~20% (range 10–30...

Signet ring sign (bronchiectasis)

The signet ring sign is seen in bronchiectasis when the dilated bronchus and accompanying pulmonary artery branch are seen in cross-section. The bronchus and artery should be the same size, whereas in bronchiectasis, the bronchus is markedly dilated. The signet ring analogy has also been applie...

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