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.

1,561 results found
Article

Episternal ossicles

Episternal (or suprasternal) ossicles are accessory bones and a normal variant of the sternum. They result from supernumerary ossification centers and are seen in ~4% (range 1-7%) of the population. Gross anatomy Episternal ossicles are usually located posterior or superior to the superior bor...
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Epithelial-myoepithelial carcinoma of lung

Epithelial-myoepithelial carcinoma of lung is a very rare type of lung carcinomas of the salivary gland type. Pathology Diagnosis is based on the identification of myoepithelial cells, with spindle cells, clear cells, or plasmacytoid differentiation or a mixture of phenotypes, along with a var...
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Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell, non-familial multisystemic granulomatosis, with widespread manifestations and of highly variable severity. The most common presenting symptom is bone pain. Epidemiology Erdheim-Chester disease is a rare, non-inherited disease of midd...
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Erdheim-Chester disease (pulmonary manifestations)

Pulmonary manifestations of Erdheim-Chester disease are uncommon. Epidemiology The lungs are affected in ~25% (range 20-35%) of cases 5.  Radiographic features HRCT chest Described findings include 1 symmetric reticular interstitial opacities smooth interlobular septal thickening and fiss...
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Erect chest x-ray (summary)

This is a basic article for medical students and other non-radiologists Erect chest x-rays are standard positioning but are also a specific examination performed for the assessment of subdiaphragmatic free gas (pneumoperitoneum). Reference article This is a summary article; we do not have a m...
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Evaluation of endotracheal tube position

Endotracheal tubes (ETT) are wide-bore plastic tubes that are inserted into the trachea to allow artificial ventilation. Tubes come in a variety of sizes and have a balloon at the tip to ensure that gastric contents are not aspirated into the lungs. Adult tubes are usually approximately 1 cm in ...
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Ewing sarcoma (chest wall)

Ewing sarcoma family of tumors (ESFT), also referred as Ewing sarcomas of the chest wall, are malignant tumors affecting children and young adults, originating either from the osseous structures or the soft tissues of the chest wall.  On imaging, they are usually characterized as a large extrap...
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Exogenous lipoid pneumonia

Exogenous lipoid pneumonia is a form of lipoid pneumonia. Please refer to the main article for a broad discussion.  In terms of the onset of the presentation, it can be divided into two different forms: acute exogenous lipoid pneumonia uncommon and typically is caused by an episode of aspirat...
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Expiratory HRCT

Expiratory HRCT is an useful method for detecting small airway obstructive disease in which the air remain trapped in the small airways even after the expiration and appear as mosaic attenuation. Indication Ideally, an expiratory HRCT scan should be performed in all obstructive airway diseases...
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External intercostal muscle

The external (or outermost) intercostal muscles are important muscles of respiration. They number eleven on each side and are located in the intercostal space, expanding the transverse dimension of the thoracic cavity during inspiration. Gross anatomy The external intercostal muscles are the o...
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Extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is used as a modified pulmonary or cardiopulmonary bypass technique in those with severe cardiac and/or respiratory failure refractory to conventional ventilatory support and medical intervention 1,3. There are two access paths for extracorporeal life s...
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Extramedullary hematopoiesis

Extramedullary hematopoiesis is a response to the failure of erythropoiesis in the bone marrow. This article aims to a general approach on the condition, for a dedicated discussion for a particularly involved organ, please refer to the specific articles on:  extramedullary hematopoiesis in the...
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Extrapleural air sign

The extrapleural air sign is one of the many signs of pneumomediastinum, and was first described by Lillard and Allen in 1965. It is defined as the presence of gas between the parietal pleura and the diaphragm. On a lateral projection the gas forms a radiolucent pocket of gas posterior to the do...
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Extrapleural fat

Extrapleural fat is benign condition and refers to relaitve 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 t...
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Extrapleural fat sign

The extrapleural fat sign is an imaging feature which can be seen on CT under certain circumstances. It occurs from the inward displacement of extrapleural fat by an extrapleural fluid collection, extrapleural hematoma or extrapleural mass. The presence of the extrapleural fat sign is indicative...
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Extrapleural hematoma

Extrapleural hematomas are uncommon and usually seen in the context of rib fracture, subclavian venous catheter traumatic insertion, and blunt chest injury. Pathology Extrapleural hematomas result from the accumulation of blood in the extrapleural space where the overlying extrapleural fat is ...
Article

Extrapleural sign

The extrapleural sign, described by Ben Felson in 1973 1, refers to the appearance of a pulmonary opacity with oblique margins that taper slowly to the chest wall when the lesion is viewed tangentially to the x-ray beam. This appearance suggests that the lesion is pleural or extrapleural in natu...
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Exudate

An exudate is a collection that has a relatively high specific gravity and protein concentration. They occur as the result of an inflammatory process that either increases the permeability of the surrounding membrane or disrupts the ability of resorption of fluid. They may be secondary to: infe...
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Fallen lung sign

The fallen lung sign (also known as CT fallen lung sign) describes the appearance of collapsed lung away from the mediastinum encountered with tracheobronchial injury (in particular those >2 cm away from the carina). It is helpful to look for this rare but specific sign, in cases of unexplained ...
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Fat containing solitary pulmonary nodule

The differential of a fat containing solitary pulmonary nodule is very narrow. In a well circumscribed smooth or lobulated mass (especially if it has been largely stable in size over time) presence of fat is essentially pathognomonic of a pulmonary hamartoma, and usually not further assessment ...
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Fat containing thoracic lesions

There is a long list of fat containing thoracic lesions. They may involve the mediastinum, lung, pleura or chest wall. Differential diagnosis includes:  intrapulmonary: fat containing pulmonary lesions pulmonary hamartoma endobronchial lipoma intrapulmonary lipoma lipoid pneumonia myeloli...
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Fat embolism syndrome

Fat embolism syndrome (FES) is a rare clinical condition caused by circulating fat emboli leading to a multisystemic dysfunction. The classical clinical triad consists of: respiratory distress cerebral abnormalities petechial hemorrhages Epidemiology It occurs in ~2.5% (range 0.5-4%) of tho...
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Fat stranding on CT

Fat stranding is a common sign seen on CT wherever fat can be found. It is most commonly seen in abdomen/pelvis, but can also be seen in retroperitoneum, thorax and subcutaneous tissues. It can be helpful in localising both acute and chronic pathology. Radiographic features CT Fat stranding c...
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Fatty mediastinal masses (differential)

Fatty mediastinal masses are relatively uncommon, and the differential diagnosis is brief, including 1-4: lipoma liposarcoma thymolipoma benign mature teratoma lipoblastoma extravasation of lipid-rich hyperalimentation fluid 3 fibrofatty replacement of the central portion of mediastinal l...
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Feeding vessel sign

Feeding vessel sign consists of a distinct vessel leading directly to a nodule or a mass. This sign indicates either that the lesion has a haematogenous origin or that the disease process occurs near small pulmonary vessels.  A number of vessel-related non-neoplastic disorders of the lung produ...
Article

Feingold syndrome

Feingold syndrome is characterized by the combination of: microcephaly digital abnormalities alimentary tract atresias especially esophageal atresia
Article

Feline esophagus

Feline esophagus also known as esophageal shiver, refers to the transient transverse bands seen in the mid and lower esophagus on a double contrast barium swallow. Pathology The appearance is almost always associated with active gastro-esophageal reflux 2,3 and is thought to be due to contract...
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Ferruginous body

A ferruginous body is a histological finding in interstitial lung disease that is a result inorganic dust inhalation. Macrophage ingestion of the inorganic fiber results in a fibrotic reaction with encasement of the fiber in iron-rich material that is derived from proteins such as ferritin and ...
Article

FEV1/FVC ratio

The FEV1/FVC ratio (FEV1%), also known as the Tiffeneau-Pinelli index, is a spirometric parameter and refers to a calculated ratio which represents the proportion of a patients vital capacity that they are able to expire in the first second of forced expiration. FEV1% is used in the diagnosis a...
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Fibrinous pericarditis

Fibrinous pericarditis results from fine granular roughening of the pericardium. Clinical presentation Pericardial friction rub may be heard. Pathology Causes viral acute idiopathic tuberculosis pyogenic acute rheumatic fever myocardial infarction: Dressler syndrome chronic renal fail...
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Fibrobullous disease

Fibrobullous disease is an observational finding where there are bullous spaces interspersed by areas of scarring (fibrosis). In general, there may be an apical predilection. This has been described in association with conditions such as: ankylosing spondylitis 1 rheumatoid arthritis 2
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Fibrosarcoma of the chest wall

Fibrosarcoma of the chest wall refers to a malignant tumor arising from the chest wall. Epidemiology It typically presents in adults, although the age range of presentation is wide. It rarely occurs as a congenital form in infants and children 2. Pathology In the thorax, fibrosarcomas usuall...
Article

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 ...
Article

Fibrothorax

Fibrothorax is defined as fibrosis within the pleural space and is sometimes referred to as pleural peel. It occurs secondary to the inflammatory response to one of the following events:   tuberculosis / tuberculous pleuritis / tuberculous empyema: mainly as a late sequela 3 thoracic empyema ...
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Fibrotic idiopathic interstitial pneumonia

The term fibrotic idiopathic intersitial pneumonia (FIIP) is refers to a morphological subset of idiopathic interstitial pneumonia where there is great then 5% of honeycombing present on HRCT 1. See also fibrotic non specific interstitial pneumonitis
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Fibrotic non-specific interstitial pneumonitis

Fibrotic non-specific interstitial pneumonitis is a histological subtype of non-specific interstitial pneumonitis (NSIP). It is considered the more common form 1. This pattern manifests as chronic interstitial inflammation obscured by interstitial fibrosis (with dense collagen), a temporal homog...
Article

Figure 3 sign

The figure 3 sign is seen in aortic coarctation and is formed by prestenotic dilatation of the aortic arch and left subclavian artery, indentation at the coarctation site (also known as the "tuck"), and post-stenotic dilatation of the descending aorta. On barium studies of the esophagus in pati...
Article

Finger clubbing

Finger clubbing, also called "drumstick fingers", is a common clinical sign in patients with heart or lung disease. The term is used to describe an enlargement of the distal phalanges of the fingers, giving them a drumstick or club-like appearance.  Clinical Presentation Finger clubbing presen...
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Finger in glove sign (lung)

The finger in glove sign can be seen on either a chest radiograph or CT chest and refers to the characteristic sign of a bronchocoele. The same appearance has also been referred to as: rabbit ear appearance mickey mouse appearance toothpaste-shaped opacities Y-shaped opacities V-shaped opac...
Article

First rib

The first rib is the most superior of the twelve ribs. It is an atypical rib and is an important anatomical landmark and is one of the borders of the superior thoracic aperture. Gross anatomy Osteology Compared to a typical rib, the first rib is short and thick and it has a single articular f...
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Flail chest

Flail chest or flail thoracic segment occurs when three or more contiguous ribs are fractured in two or more places. Clinically, a segment of only one or two ribs can act as a flail segment, hence there is some controversy between the clinical and radiological definitions. Clinical presentation...
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Flattening of the diaphragm

Flattening of the diaphragm is the most sensitive sign on chest radiographs for the presence of hyperinflation of the lungs, usually due to emphysema 1-2. The normal dome of each hemidiaphragm should rise at least 1.5 cm above a line connecting the costophrenic angle posteriorly and sternophren...
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Flat waist sign

The flat waist sign refers to flattening of the left heart border, specifically the contours of the aortic arch and adjacent pulmonary trunk. It is seen in severe left lower lobe collapse and is caused by leftward displacement and rotation of the heart. It is different to the straight left hear...
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Fleischner sign (disambiguation)

Fleischner sign can refer to two distinctly separate signs: Fleischner sign (enlarged pulmonary artery) Fleischner sign (tuberculosis of ileocecal junction)
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Fleischner sign (enlarged pulmonary artery)

The Fleischner sign refers to a prominent central pulmonary artery that can be commonly caused either by pulmonary hypertension or by distension of the vessel by a large pulmonary embolus. It can be seen on chest radiographs, CT pulmonary angiography, and MR pulmonary angiography. It is seen mo...
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Fleischner Society

The Fleischner Society is a interdisciplinary learned society with the key aim to advance the study of pathologies of the chest by the use of thoracic imaging. History Eight radiologists congregated in November 1969 to found a new society to advance the knowledge of diseases of the chest, pred...
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Fleischner Society pulmonary nodule recommendations

The Fleischner Society pulmonary nodule recommendations pertain to the follow-up and management of pulmonary nodules detected incidentally on imaging. The guideline does not apply to lung cancer screening, patients younger than 35 years, or patients with a history of primary cancer or immunosupp...
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Fluid bronchogram sign

The fluid bronchogram sign can be seen on chest CT or ultrasound as the presence of fluid attenuation material within respiratory bronchioles with surrounding collapsed or consolidated lung. The presence of this sign suggests endobronchial obstruction as a precipitating cause for consolidation/...
Article

Fluid color sign

The fluid color sign is a diagnostic sign to differentiate a pleural effusion from pleural thickening by means of color Doppler ultrasound. In the case of pleural effusion a color signal is seen in the pleural fluid during respiratory and cardiac movement, whereas this color signal is not seen i...
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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...
Article

Focal interstitial pulmonary fibrosis

Focal interstitial pulmonary fibrosis refers to a manifestation of pulmonary fibrosis where changes are confined and localised to a small region of the lung, they can arise of range of etiologies with one rather common example being osteophyte induced adjacent pulmonary atelectasis and fibrosis....
Article

Focal lymphoid hyperplasia of the lung

Focal lymphoid hyperplasia of the lung refers to an abnormal accumulation of non-malignant lymphocytic aggregates within the lung.  Terminology Previously known as pulmonary pseudolymphoma. Clinical presentation Clinical features can vary from being asymptomatic to various symptoms such as w...
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Focal pulmonary opacity (mnemonic)

Causes of focal pulmonary opacities on a chest radiograph can be remembered using the rather crude mnemonic: 4 Fs Mnemonic F: 'fection (pulmonary infection) F: 'farction (pulmonary infarction) F: fluid (pulmonary edema) F: f***ed (lung cancer)
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Follicular bronchiolitis

Follicular bronchiolitis (FB) is a nonneoplastic primary polyclonal B cell hyperplasia of the bronchus-associated lymphoid tissue (BALT) due to chronic exposure to antigens in those with underlying collagen vascular or immune deficiency diseases which usually manifested as small centrilobular gr...
Article

Folliculin gene-associated syndrome

Folliculin gene-associated syndrome (FLCN-S) or Birt-Hogg-Dubé (BHD) syndrome is a genetic multisystemic disease mainly characterized by: multiple lung cysts and secondary spontaneous pneumothoraces multiple bilateral renal tumors (particularly chromophobe renal cell cancer and oncocytoma) cu...
Article

Foramen of Morgagni

The foramina of Morgagni, also known as the sternocostal triangles, are small defects in the posterior aspect of the anterior thoracic wall between the sternal and costal attachments of the diaphragm. The internal thoracic vessels descend through these foramina to become the superior epigastric ...
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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 cysts l...
Article

Funnel trachea

Funnel trachea is a colloquialism for a congenital long-segment intrathoracic tracheal stenosis.  The diameter of the trachea immediately below the cricoid is normal, and becomes progressively more stenotic caudally. The posterior, membranous portion of the trachea may be partially or completel...
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Galaxy sign (lungs)

The so-called galaxy sign, initially described as the sarcoid galaxy, represents a coalescent granuloma seen in a minority of patients with pulmonary sarcoidosis 1. The same appearance can be seen in tuberculosis 2,3. In other words, it represents a mass-like region composed of numerous smaller ...
Article

Ganglioneuroma

Ganglioneuromas are fully differentiated neuronal tumors that do not contain immature elements and potentially occur anywhere along the peripheral autonomic ganglion sites.  On imaging, usually, they present as well-defined solid masses and can be quite large at presentation. Generally, they ar...
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Garland triad

Garland triad, also known as the 1-2-3 sign or Pawnbrokers 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. These so-ca...
Article

Gastro-pleural fistula

A gastro-pleural fistula is a very rare situation characterized by a pathological communication between the stomach and the pleural cavity. They can occur in number of situations: trauma (stab injuries 3) iatrogenic (following bariatric, pulmonary or esophageal surgery 1) malignancy (ovarian...
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GATA2 deficiency

GATA2 deficiency is a germ-line disease expressed as a wide spectrum of phenotypes, including monocytopenia, myelodysplasia, myeloid leukaemias, and lymphoedema. It is a rare cause of pulmonary alveolar proteinosis. Clinical presentation GATA2 deficiency has considerably variable clinical mani...
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Geneva score

The Geneva score, similarly to the Wells score, is a clinical stratifying system to estimate the probability of pulmonary embolism (PE) in patients in which this diagnosis was considered. The criteria were originally published by the clinical team of the Geneva University Hospital in 2001 1, and...
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Ghon lesion

A Ghon lesion (sometimes called Ghon focus) represents a calcified tuberculous caseating granuloma (tuberculoma) and represents the sequelae of primary pulmonary tuberculosis infection. When associated with a calcified ipsilateral hilar node it is known as a Ranke complex. History and etymolog...
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Giant cell interstitial pneumonia

Giant cell interstitial pneumonia is a rare form of pulmonary fibrosis. It is currently considered form of pneumoconiosis and in many situations is caused by exposure to metal compounds such as cobalt or tungsten carbide. While some authors consider this term to be synonymous with or being almo...
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Ginkgo leaf sign (chest)

The ginkgo leaf sign of the chest, also referred as the ginkgo leaf sign of subcutaneous emphysema, is a radiograph appearance which is seen with extensive subcutaneous emphysema of the chest wall. Gas outlines the fibers of the pectoralis major muscle and creates a branching pattern that resemb...
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Golden S-sign (lung lobe collapse)

The Golden S-sign is seen on both PA chest radiographs and on CT scans. It is named because this sign resembles a reverse S shape, and is therefore sometimes referred to as the reverse S-sign of Golden. Although typically seen with right upper lobe collapse, the S-sign can also be seen with the...
Article

Goodpasture syndrome

Goodpasture syndrome, also referred as antiglomerular basement membrane (anti-GBM) antibody disease, is an autoimmune disease characterized by damage to the alveolar and renal glomerular basement membranes by a cytotoxic antibody. It is a type of pulmonary-renal syndrome. Goodpasture syndrome i...
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Good syndrome

Good syndrome is a rare paraneoplastic syndrome in which a thymoma causes hypogammaglobulinemia and humoral immunodeficiency. It has been estimated to occur in 0.2%–2% of thymomas 2. thymoma low to absent B-cells T-cell mediated defects CD4 T-cell lymphopenia inverted CD4/CD8+ T-cell ratio ...
Article

Graft versus host disease (pulmonary manifestations)

Pulmonary graft versus host disease (GvHD) is one of the thoracic manifestations that can complicate hematopoietic stem cell transplantation. Pulmonary GvHD can be broadly divided into acute and chronic disease 1-4: acute pulmonary GvHD pulmonary involvement is rare the median time of onset o...
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Granulomatosis with polyangiitis

Granulomatosis with polyangiitis (GPA), previously known as Wegener granulomatosis, is a multisystem necrotizing non-caseating granulomatous c-ANCA positive vasculitis affecting small to medium sized arteries, capillaries and veins, with a predilection for the respiratory system and kidneys 3. ...
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Granulomatosis with polyangiitis (pulmonary manifestations)

This article discusses the pulmonary manifestations of granulomatosis with polyangiitis (previously known as Wegener granulomatosis). It is classified as a type of pulmonary angiitis and granulomatosis. For a general discussion of the condition, please refer to the main article on granulomatosi...
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Granulomatous bronchiolitis

Granulomatous bronchiolitis is a pathological type of bronchiolitis (not an imaging classification) characterized by an underling granulomatous reaction involving the small airways (bronchioles).  Pathology It is grouped as form of cellular bronchiolitis 1 Causes It can be associated with a ...
Article

Granulomatous lung disease

Granulomatous lung disease refers to a broad group of infectious and non-infections conditions characterized by the formation of granulomas. The spectrum includes infectious mycobacterial pulmonary tuberculosis pulmonary non-tuberculous mycobacterial infection fungal pulmonary coccidioido...
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Granulomatous lymphocytic interstitial lung disease

Granulomatous-lymphocytic interstitial lung disease (GLILD) is a relatively recent term given to describe non-infectious, diffuse lung disease complications that develop in common variable immunodeficiency (CVID) patients. Pathology They exhibit both granulomatous and lymphoproliferative histo...
Article

Gravity dependent atelectasis

Gravity dependent atelectasis refers to a form of lung atelectasis which occurs in the dependent portions of the lungs due to a combination of reduced alveolar volume and increased perfusion. Being due to gravity, it usually has a dependent and subpleural distribution. It is very commonly seen i...
Article

Ground-glass opacification

Ground-glass opacification/opacity (GGO) is a descriptive term referring to an area of increased attenuation in the lung on computed tomography (CT) with preserved bronchial and vascular markings. It is a non-specific sign with a wide etiology including infection, chronic interstitial disease an...
Article

H1N1 influenza

H1N1 influenza is a strain of influenza that notably resulted in a pandemic in 2009. Pathology It is caused by a type of influenza A virus of swine origin. Clinical presentation There can be a wide spectrum of clinical syndromes ranging from being asymptomatic to fulminant viral pneumonia, r...
Article

Hemopneumothorax

Hemopneumothorax is a term given when there is concurrent presence of a hemothorax and well as a pneumothorax. It is a variant of a hydropneumothorax.  Epidemiology Approximately 5% of patients with pneumothorax will have concomitant hemothorax 6 . Pathology It is typically seen in the setti...
Article

Hemoptysis

Hemoptysis refers to coughing out blood. Generally, it appears bright red in color as opposed to blood from the gastrointestinal tract which appears dark red. It is considered an alarming sign of a serious underlying etiology. Terminology Massive hemoptysis is referred to as expectoration of >...
Article

Hemorrhagic metastases (mnemonic)

A mnemonic for primary malignancies responsible for hemorrhagic metastases is: MR CT BB Mnemonic M: melanoma: metastatic melanoma to brain R: renal cell carcinoma C: choriocarcinoma T: thyroid carcinoma, teratoma B: bronchogenic carcinoma B: breast carcinoma
Article

Hemorrhagic pneumonia

Hemorrhagic pneumonia refers to a descriptive term for pneumonia (infective - inflammatory consolidation of the lung) when is complicated by pulmonary hemorrhage. It can be localised or diffuse to varying degrees dependent on the extent of involvement +/- aetiological agent. Pathology The prec...
Article

Hemorrhagic pulmonary metastases

Hemorrhagic pulmonary metastases are those which tend to be complicated by pulmonary hemorrhage within them, resulting in characteristic imaging appearances.  Metastases of some tumor histologies are more likely to hemorrhage -- knowledge of this can help refine the differential diagnoses. Path...
Article

Hemothorax

Hemothorax literally means blood within the chest, is a term usually used to describe a pleural effusion due to accumulation of blood. If a hemothorax occurs concurrently with a pneumothorax it is then termed a hemopneumothorax.  A tension hemothorax refers to hemothorax that results from massi...
Article

Hairy pleural plaque

Hairy pleural plaques are a manifestation of asbestos-related disease. They arise from the visceral pleura, typically from an interlobar fissure. The hairiness stems from short radially-oriented linear regions of fibrosis extending from the plaque into the adjacent lung parenchyma. Compared to ...
Article

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 of pectus excavatum, as well as preoperative and postoperative assessment 1,5. Technique The Haller index is calculated by ...
Article

Halo sign (chest)

The halo sign in chest imaging is a feature seen on lung window settings (typically HRCT), ground glass opacity surrounding a pulmonary nodule or mass and represents hemorrhage. It is typically seen in angioinvasive aspergillosis. Pathology Histopathologically, it represents a focus of pulmona...
Article

Hamman syndrome

Hamman syndrome, also known as Macklin syndrome, refers to spontaneous pneumomediastinum along with subcutaneous emphysema. Epidemiology It is a rare entity most often encountered in young adults. It is a known entity peri- and postpartum 3. Clinical presentation The condition is most common...
Article

Hampton hump

Hampton hump refers to a dome-shaped, pleural-based opacification in the lung most commonly due to pulmonary embolism and lung infarction (it can also result from other causes of pulmonary infarction (e.g. vascular occlusion due to angioinvasive aspergillosis). While a pulmonary embolism is expe...
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Hard metal pneumoconiosis

A hard metal pneumoconiosis is usually classified as a type of fibrotic pneumoconiosis where the precipitating agent consists of a fine particulate form of hard metal such as: cobalt/cobalt-tungsten alloys 10 tungsten/tungsten carbide alloys implicated alloys often contain small amounts of ot...
Article

Haystack sign (pneumomediastinum)

The haystack sign on chest x-rays in pediatric patients is indicative of pneumomediastinum. The pediatric heart is surrounded above and below with gas, giving it an appearance of a haystack from Monet's paintings. 
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Head cheese sign (lungs)

The head cheese sign refers to a juxtaposition of regions with three different densities: ground glass opacities (high attenuation) mosaic attenuation pattern (low attenuation) normal lung tissue (normal attenuation) A mixed infiltrative (ground glass opacity) and obstructive (mosaic attenua...

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