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...
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 ...
Foregut duplication cysts are type congenital duplication cyst. They are sometimes classified under broncho-pulmonary foregut malformations.
Entities that fall under forgut duplication cysts include:
other enteric cysts
oesophageal duplication cysts
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...
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 ...
Ganglioneuromas are fully differentiated neuronal tumours 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 a...
Garland triad, also known as the 1-2-3 sign or Pawnbrokers sign, is a lymph node enlargement pattern which has been described in sarcoidosis:
right paratracheal nodes
right hilar nodes
left hilar nodes
Hilar lymphadenopathy is symmetrical and usually massive. These so-called potato nodes don...
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...
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...
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...
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 fibres of the pectoralis major muscle and creates a branching pattern that resemb...
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...
Goodpasture syndrome (or antiglomerular basement membrane (anti-GBM) antibody disease) is an autoimmune disease characterised by damage to the alveolar and renal glomerular basement membranes by a cytotoxic antibody. It is type of pulmonary renal syndrome.
Goodpasture syndrome is defined by:
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.
low to absent B-cells
T-cell mediated defects
CD4 T-cell lymphopenia
inverted CD4/CD8+ T-cell ratio
Pulmonary graft versus host disease (GvHD) is one of the thoracic manifestations that can complicate haematopoetic 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...
Granulomatosis with polyangiitis (GPA), previously known as Wegener granulomatosis, is a multisystem systemic necrotising non-caseating granulomatous vasculitis affecting small to medium sized arteries, capillaries and veins, with a predilection for the respiratory system and kidneys 3.
This article discusses the pulmonary manifestations of granulomatosis with polyangiitis (previously known as Wegener's 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 granulomato...
Granulomatous bronchiolitis is a pathological type of bronchiolitis (not an imaging classification) characterised by an underling granulomatous reaction involving the small airways (bronchioles).
It is grouped as form of cellular bronchiolitis 1
It can be associated with a ...
Granulomatous lung disease refers a broad group of infectious and well as non infections conditions characterised by formation of granulomas.
The spectrum includes
pulmonary non tuberculous mycobacterial infection
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 aetiology including infection, chronic interstitial disease a...
H1N1 influenza is a strain of influenza that notably resulted in a pandemic in 2009.
It is type of influenza A virus of swine origin.
There can be a wide spectrum of clinical syndromes with patient's ranging from being asymptomatic to having fulminating viral p...
Haemopneumothorax is a term given when there is concurrent presence of a haemothorax and well as a pneumothorax. It is a variant of a hydropneumothorax.
Approximately 5% of patients with pneumothorax will have concomitant haemothorax 6
It is typically seen in the sett...
Haemoptysis refers to coughing out blood. Generally, it appears bright red in colour as opposed to blood from gastrointestinal tract which appears dark red. It is considered an alarming sign of a serious underlying aetiology.
Massive haemoptysis is referred to as expectoration of >...
A mnemonic for primary malignancies responsible for haemorrhagic metastases is:
MR CT BB
M: melanoma: metastatic melanoma to brain
R: renal cell carcinoma
T: thyroid carcinoma, teratoma
B: bronchogenic carcinoma
B: breast carcinoma
Haemorrhagic pneumonia refers to a descriptive term for a pneumonia (infective - inflammatory consolidation of the lung) when is complicated by pulmonary haemorrhage. It can be localised or diffuse to varying degrees dependant on the extent of involvement +/- aetiological agent.
Haemorrhagic pulmonary metastases are those which tend to be complicated by pulmonary haemorrhage within them, resulting in characeristic imaging appearances. Metastases of some tumour histologies are more likely to haemorrhage -- knowledge of this can help refine the differential diagnoses.
Haemothorax literally means blood within the chest, is a term usually used to describe a pleural effusion due to accumulation of blood. If a haemothorax occurs concurrently with a pneumothorax it is then termed a haemopneumothorax.
A tension haemothorax refers to haemothorax that results from ...
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.
The halo sign (HS) in chest imaging is a feature seen on lung window settings (typically HRCT), ground glass opacity surrounding a pulmonary nodule or mass and represents haemorrhage. It is typically seen in angioinvasive aspergillosis.
Histopathologically, it represents a focus of p...
Hamman syndrome, also known as Macklin syndrome, refers to spontaneous pneumomediastinum along with subcutaneous emphysema.
It is a rare entity most often encountered in young adults. It is a known entity peri- and postpartum 3.
The condition is most common...
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 artery embolism ...
A hard metal pneumoconiosis is usually classified as a type of fibrotic pneumoconiosis where the precipitating agent consists of a hard metal (not a heavy metal) such as.
tungsten / tungsten carbide alloys
or a mixture
A more broader term used is hard metal lung disease (...
The haystack sign on chest x-rays in paediatric patients is indicative of pneumomediastinum. The paediatric heart is surrounded above and below with gas, giving it an appearance of a haystack from Monet's paintings.
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...
The heart is a hollow, muscular organ of the middle mediastinum, designed to pump oxygenated blood around the systemic circulation and de-oxygenated blood around the pulmonary circulation
The heart has a somewhat conical form and is enclosed by pericardium. It is positioned poste...
There are four heart chambers, the right atrium, left atrium, right ventricle and left ventricle. These receive blood from the body and lungs, and contract to transmit blood to the lungs for oxygenation and to the body for use in metabolism.
It is best to list the four chambers in order of the ...
This is a basic article for medical students and other non-radiologists
Heart failure is a syndrome of cardiac ventricular dysfunction, where the heart is unable to pump sufficiently to meet the body's blood flow requirements.
Although it is useful to divide the signs an...
The Heiner syndrome is a rare form of primary pulmonary haemosiderosis associated with an allergy to cow's milk. The syndrome includes:
rectal blood loss with hypochromic microcytic anaemia
pulmonary infiltrates (often recurrent)
There are many thoracic complications that can occur following haematopoietic stem cell transplantation. These can precipitate during various stages following transplantation and can be either infectious or noninfectious.
The hemiazygos vein is the asymmetric counterpart to the azygos vein and forms part of the azygos venous system.
The hemiazygos vein is formed by the confluence of the left ascending lumbar and left subcostal veins.
The hemiazygos vein enters the thorax either ...
Complete white-out of a hemithorax on the chest x-ray has a limited number of causes. The differential diagnosis can be shortened further with one simple observation: the position of the trachea. Is it central, pulled or pushed from the side of opacification? Is there pulmonary volume loss or vo...
Hepatic hydrothorax (HH) is an uncommon manifestation of cirrhosis with ascites. It is one of the pulmonary complications of cirrhosis with portal hypertension.
It is characterised by formation of pleural effusions usually greater than 500 mL, in patients with portal hypertension without any o...
Pulmonary hepatisation refers to the alteration of lung tissue such that it resembles liver tissue. It is a stage of lobar pneumonic consolidation. In the early stage, haemorrhagic fluid accumulates within the alveoli and gets organised resulting to the pathological appearance called "red hepati...
Hepatopulmonary syndrome (HPS) refers to the combination of
hepatic dysfunction (cirrhosis)
hypoxaemia (alveolar-arterial O2 gradient of >15mmHg; >20mmHg in >64year old patients).
peripheral pulmonary arterial dilatation (due to right to left micro-shunts).
It is estimated to b...
Hereditary connective tissue diseases are a group of connective tissue disease that have a degree of inheritance risk. They include :
Marfan syndrome - genetic disease causing abnormal fibrillin
Ehlers-Danlos syndrome - progressive deterioration of collagen and affects joints, heart v...
Hereditary haemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare inherited disorder characterised by abnormal blood vessel formation in the skin, mucous membranes, and organs including the lungs, liver, and central nervous system.
Hermansky-Pudlak syndrome (HPS) is a rare syndrome which consists of:
oculocutaneous hypopigmentation (albinism)
abnormal storage of autofluorescent pigment (ceroid or lipofuscin)
typically occurs within lysosomal organelles of the cells of multiple organs and the reti...
Heroin induced pulmonary oedema is an aetiological subtype of non cardiogenic pulmonary oedema. It may be prevalent in up to 40% of patients admitted with a heroin overdose 2.
It is defined by some authors as a syndrome in which a patient develops significant hypoxia (room air saturation< 90% w...
Hiatus hernias (HH) occur when there is herniation of abdominal contents through the oesophageal hiatus of the diaphragm into the thoracic cavity.
The prevalence of hiatus hernia increases with age, with a slight female predilection.
Many patients with hiat...
High altitude pulmonary oedema is a subtype of pulmonary oedema and is caused by prolonged exposure to an environment with a lower partial oxygen atmospheric pressure.
It occurs most frequently in young males and ~24-48 hours after they have made a rapid ascent to heights greater ...
High attenuation lymphadenopathy has been described with:
Kaposi sarcoma 1,6
angioimmunoblastic lymphadenopathy (AILD)
Kimura disease (due to nodal haemorrhage) 6
metastatic hypernephroma (presumed due to nodal haemorrahage) 6
If there is calcification associa...
The hilar point on chest radiographs is formed by the outer margins of the superior pulmonary vein and the descending pulmonary artery as they cross past each other.
The hilum convergence sign is a useful chest radiograph sign to help distinguish a bulky hilum due to pulmonary artery dilatation from a mass/nodal enlargement. In the former, pulmonary vessels can be seen to converge and join a dilated pulmonary artery.
History and etymology
Dr Benjamin Fels...
The hilum overlay sign refers to the appearance of an abnormally dense hilum on frontal chest radiographs.
If a mass arises from the hilum, the normal pulmonary vessels (interlobar artery, upper lobe arteries, and left descending artery) 2 are in contact with the mass and their silhouette is ob...
Acquired immunodeficiency syndrome (AIDS) is an immunosuppressed state, caused by infection with the human immunodeficiency virus (HIV). It is characterised by opportunistic infections, neoplasms and neurological manifestations.
According to the United Nations programme on HIV/AID...
Pulmonary manifestations of HIV/AIDS are a major contributor to morbidity and mortality related to the disease. The differential in an HIV patient with a chest complaint is broad. Infectious causes are the most common, however, neoplasms, lymphoma and interstitial pneumonias also play a signifi...
HIV associated follicular bronchiolitis is a form of bronchiolitis that occurs in those with HIV.
It has been described in both HIV-positive children and adults.
It is manifested by bronchial-associated lymphoid tissue hyperplasia thought to be due to repetitive antige...
HIV-associated neoplasms are numerous and can be broadly divided into two groups:
associated but not AIDS defining malignancies
The development of these malignancies in HIV affected individuals generally implies progression to AIDS 4:
Pulmonary manifestations of Hodgkin lymphoma are relatively rare, present in 5-12% of patients at the time of diagnosis. It is relatively more common with the nodular sclerosing subtype. Pulmonary involvement usually indicates stage IV disease.
Bilateral involvement is ...
The Hoffman-Rigler sign is a sign of left ventricular enlargement where an approximation of the distance between the inferior vena cava (IVC) and left ventricle is used.
On a lateral chest radiograph, if the distance between the left ventricular border and the posterior ...
The holly leaf sign refers to the appearance of pleural plaques on chest x-rays. Their irregular thickened nodular edges are likened to the appearance of a holly leaf.
Holt-Oram syndrome (HOS) is an autosomal dominant syndrome that results in congenital heart defects and upper limb anomalies:
congenital heart defects
atrial septal defect (ASD) (commonest cardiac defect 4)
ventricular septal defect (VSD)
upper limb abnormalities
Honeycombing refers to the CT manifestation of diffuse pulmonary fibrosis (usual interstitial pneumonia). The Fleischner Society definition is clustered cystic air spaces (between 3-10 mm in diameter but occasionally as large as 2.5 cm) which are usually subpleural and basal in distribution. The...
The horizontal fissure (also called the minor fissure) is a unilateral structure in the right lung that separates the right middle lobe from the right upper lobe.
The horizontal fissure arises from the right oblique fissure and follows the 4th intercostal space from the sternum u...
Horseshoe lung is one of the rare congenital anomalies of the lung. A band of pulmonary parenchyma is formed extending between the right and left lungs. The pulmonary tissue can be seen either anterior to the aorta or posterior to the pericardium at the caudal end.
Hospital-acquired pneumonia (HAP) or nosocomial pneumonia is defined by the American Thoracic Society (ATS) guidelines as pneumonias that occur more than 48 hours after hospital administration but were not present at the time of admission.
It can be a common cause of pneumonia in ...
Hot tub lung refers to pulmonary disease in otherwise healthy patients that can occur by secondary exposure to aerosolized non-tuberculous mycobacteria in contaminated hot water-steam (classically described in hot tubs, hence the name).
It can present as an acute pulmona...
A hybrid lesion in paediatric chest radiology refers to a combination of a congenital pulmonary airways malformation (CPAM) and a pulmonary sequestration (most commonly extralobar). It falls under a type of bronchopulmonary foregut malformation. Due to more sophisticated imaging, they are increa...
There are several signs in hydatid cyst are seen in associated with hydatid disease:
cumbo sign: air is seen between the pericyst and the laminated membrane of the cyst
serpent sign: internal rupture of the cyst with collapse of membranes of parasite into the cyst
spin sign/whirl sign: deta...
Hydatid cysts result from infection by the Echinococcus, and can result in cyst formation anywhere in the body.
There are two main species of the Echinococcus tapeworm 1,2:
pastoral: dog is a main host; most common form
sylvatic: wolf is a main ...
Hydropneumothorax is a term given to the concurrent presence of a pneumothorax as well as a hydrothorax (i.e. air and fluid) in the pleural space.
It may arise in various situations which include
A hyparterial bronchus is any bronchus originating inferior to the level of the pulmonary artery. Conversely, the right superior lobar bronchus can be referred to by its anatomical relationship to the pulmonary arteries as being eparterial.
The term may be encountered in the classification of ...
Hyperattenuating pulmonary abnormalities can result from a variety of processes, and have varied radiographic appearances. It is easiest, for the purposes of radiology, to divide them into:
hyperdense linear or reticular opacities
hyperdense pulmonary nodules
hyperdense pulmonary mass
Hypercontracting (nutcracker) oesophagus is a motility disorder of the oesophagus. This condition is primarily diagnosed with manometry with high intra-oesophageal pressure and normal peristalsis. Most patients will have a normal barium swallow.
Hypercontracting oesophagus ("nutcracker oesopha...
There are only a few causes of a pulmonary mass with internal calcification. They include:
granuloma: most common
mucoid calcification of mucinous adenocarcinoma:
gastrointestinal tract ad...
Hyperimmunoglobulin E (hyper IgE) syndrome (HIES), also known as Job syndrome, consists of heterogeneous group of complex hereditary combined B- and T-cell immune deficiency diseases characterised by recurrent Staph aureus chest infections, characteristic coarse facial appearance and dental prob...
Hypersensitivity pneumonitis (HP), also known as extrinsic allergic alveolitis, represents a group of pulmonary disorders mediated by an inflammatory reaction to inhalation of an allergen. These may be organic or inorganic particles (microbes, animal or plant proteins, and certain chemicals) tha...
CT scoring systems have been proposed in patients with acute respiratory distress syndrome (ARDS) to predict clinical outcomes. This scoring system was established by Ichikado et al. in 2006 2 and at the time of writing (July 2016), this is the most widely used CT scoring system.
Idiopathic dilatation of the pulmonary trunk is a rare congenital anomaly comprising of pulmonary trunk enlargement with or without dilatation of the right and left pulmonary arteries.
For this diagnosis, exclusion of pulmonary and cardiac diseases (mainly pulmonary valve stenosis) and confirma...
Idiopathic giant bullous emphysema, also known as vanishing lung syndrome (VLS), is characterised by giant emphysematous bullae, which commonly develop in the upper lobes and occupy at least one-third of a hemithorax. It is a progressive condition that is also associated with several forms of em...
Idiopathic interstitial pneumonias (IIPs) are diffuse interstitial lung diseases of unknown cause. A useful mnemonic for the American Thoracic Society-European Respiratory Society (ATS-ERS) classification of IIPs is:
All Idiopathic Chronic Lung Disease aRe Nonspecifically Patterned
Idiopathic interstitial pneumonias (IIPs) are diffuse interstitial lung diseases of unknown cause. They are characterized by cellular infiltration of the interstitial compartment of the lung with varying degrees of inflammation and fibrosis.
For many years many attempts have bee...
The approach to HRCT chest in patients with suspected idiopathic interstitial pneumonia (IIP) is with the aim to:
make sure an appropriate study requested i.e. HRCT chest with optimal individually adjusted protocol and ensure adequacy of the HRCT chest quality (see imaging protocol below)
Idiopathic pauci immune pulmonary capillaritis (IPIPC) is considered a rare type of pulmonary vasculitis. Some authors consider this due be an organ specific subset of microscopic polyangiitis 3. It can result in diffuse alveolar haemorrhage.
It is an isolated small vessel vasculitis...
Idiopathic pneumonia syndrome (IPS) refers to diffuse lung injury which can occur following haematopeotic stem cell transplantation where neither an infectious nor non-infectious aetiology can be found.
The incidence of IPS is thought to be around 12% following haematopoetic stem ...
Idiopathic pulmonary fibrosis (IPF) is a clinical syndrome and considered the most common and the most lethal form of pulmonary fibrosis corresponding to the histologic and imaging pattern of UIP. It is more common in middle age or elderly men and diagnosed by:
histological or imaging pattern ...
Idiopathic pulmonary haemosiderosis (IPH) is an uncommon form of pulmonary haemosiderosis. It is characterised by the triad of
iron deficiency anemia
diffuse pulmonary infiltrates, usually represented by diffuse pulmonary haemorrhage
The diagnosis is usually made by exclusion 1.
Idiopathic pulmonary ossification (also known as bony metaplasia of lung) is a rare disorder with unknown cause characterised by bony tissue within the lung.
The condition is asymptomatic but mild symptoms, restrictive pulmonary physiology, and impaired transfer factor hav...
IgG4-related disease (IgG4-RD) is a systemic disease that is characterised by extensive IgG4-positive plasma cells and T-lymphocyte infiltration of various organs.
This condition has been known by many other names in the past, such as IgG4-related sclerosing disease, IgG4-related s...
IgG4-related lung disease is a recently described condition. It may occur with or without systemic involvement. It is considered part of the spectrum of IgG-4 related disease.
On HRCT of the chest, it may be categorised into four major subtypes 5:
solid nodular type
Immune reconstitution inflammatory syndrome (IRIS) is paradoxical deterioration of a pre-existing illness following abrupt improvement in an individual's immune function. It is classically seen in HIV/AIDS patients following initiation of highly active anti-retroviral therapy (HAART). Increasing...
Implantable loop recorders, also known as insertable cardiac monitors, are small insertable devices that continuously monitor and record cardiac rhythms. They are placed subcutaneously and used for the evaluation of patients with recurrent unexplained episodes of palpitations or syncope. They sh...
Incidental lung nodules are encountered commonly in routine cross sectional imaging. The risk of developing cancer in very small nodules (<5mm) is very low. However, clear-cut recommendations are still not in place with high variation in practice amongst reporting radiologists 1. As a result, it...