Differentiating benign from malignant pulmonary nodules is of great importance as it determines the further course of management of the patient.
Benign pulmonary nodule
size: the smaller the size the more likely to be benign
~80% of benign nodules are <2 cm in size.
margin: smooth, regular; ...
Protracted bacterial bronchitis is one of the most common causes of cough in children, particularly those aged <6 years. Is it characterized by a chronic wet cough with no associated cause and tends to respond to 2 weeks of antibiotic therapy.
Protracted bacterial bronchitis is th...
This article lists examples of normal imaging divided by body region and system.
head and neck
Pneumonitis is a broad descriptive term indicating inflammation of the lung. In clinical practice and more specifically radiology, pneumonitis refers to inflammation of the pulmonary interstitium. The term is often used interchangeably with interstitial pneumonia.
Acute esophageal necrosis (sometimes known as Black esophagus or esophageal stroke), is a rare entity characterized by patchy or diffuse circumferential black pigmentation of the esophageal mucosa from ischemic necrosis.
It is classically characterized by a striking endoscopic image of diffuse,...
Peribronchiolar metaplasia is a partially recognized pathological entity characterized by fibrosis of the alveolar septa adjacent to terminal bronchioles and alveolar ducts, with bronchiolar-type epithelial metaplasia of the peribronchiolar alveolar walls. It is currently only accepted by some a...
Pulmonary mycobacterium chimerae infection if a rare form of non-tuberculous myobacterial infection.
Although rare it is recognized as an emerging opportunistic threat in patients undergoing coronary arterial bypass surgery and open heart procedures requiring extracorporeal devic...
Thymic calcifications are rare findings usually associated with thymoma but are also seen in other pathologies.
thymoma - more frequent in invasive thymoma 1
multilocular thymic cyst 2
anterior mediastinal amyloidosis 3
Pulmonary hemorrhage complicating multifocal infection is one of the causes of diffuse pulmonary hemorrhage (and particularly diffuse alveolar hemorrhage). The type of infection can depend on immunocompetency status as well as presence of absence of concurrent vasculitic, connective tissue or co...
Bilateral hypertranslucent hemithoraces is the presence of decreased density of the hemithoraces bilaterally on a plain chest radiograph. This hypertranslucency, a.k.a. hyperlucency, may be focal or diffuse 1.
Also see unilateral hypertranslucent hemithorax.
Apical chest masses are often important and may be missed, especially when examined with a plain chest radiograph. It is always recommended to perform a targeted assessment of the apices of the lungs during a chest x-ray; they are one of the classic review areas.
Migratory pulmonary consolidation, also known as wandering pulmonary consolidation, refer to air space opacities that change in location over time, and are characteristic of a subset of lung diseases.
The differential diagnoses include:
organizing pneumonia 1
recurrent aspiration pneumonia
VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a severe, treatment-refractory, monogenic, multiorgan, autoinflammatory condition with vasculitic and hematological complications.
VEXAS syndrome is likely to be rare, but also likely to be underdiagnosed...
Platypnoea-orthodeoxia syndrome refers to the concomitant occurrence of dyspnea and hypoxemia, respectively, which are precipitated by assuming an upright position and alleviated by assuming a recumbent position 4.
As the name of the syndrome suggests, the hallmark clinic...
Accessory muscles of respiration refer to muscles that provide assistance to the main breathing muscles, mainly when additional power is needed, for example during exercise or those with airway pathologies (e.g. COPD) 1,2.
During normal quiet breathing, inspiration is an active process primaril...
The pulmonary trunk to aortic ratio (PA:A), also known as main pulmonary artery to aorta ratio (MPA:A), is a measurement that can be made on CT and MRI scans and, in some instances on echocardiography 3. In most instances, a normal ratio in adults is taken 1:1 or less, and with ratios greater th...
The tracheal air column describes the appearance of the trachea on plain chest radiographs.
On frontal chest radiographs, the air column extends as an almost vertical, radiolucent column midline in the mediastinum from the inferior margin of the cricoi...
Anti SRP autoantibody associated interstitial lung disease is a form of autoimmune related interstitial lung disease.
It is thought to usually present with mild respiratory symptoms although some patients have been reported to have severe disease 1.
It is repo...
Pulmonary artery intramural hematoma (PA-IMH) refers to a hemorrhage within the wall of the pulmonary arteries. It can occur alone in the setting of a thoracic aortic injury or as a complication of an acute aortic dissection for example in a setting where the posterior wall of the aortic root is...
Tracheostomy tubes, a.k.a. tracheotomy tubes, are inserted through a stoma post-tracheostomy to help patients unable to breathe normally. It may be temporary or permanent depending on the patient's condition, with its insertion where clinically indicated showing a lowered in-hospital mortality r...
The curtain sign refers to the normal ultrasound characteristics of lung bases where the lungs are fully aerated. This is because the air in the costophrenic recess will cast a hyperechoic "air curtain" over the recess, obscuring the outline of the lateral diaphragm. The "air curtain" will also ...
Cauldwell classification is a commonly used classification in assessing bronchial artery branching pattern.
The bronchial artery branching pattern is classified into four types based on the number of intercostobronchial trunks (ICBT) - that gives rise to right bronchial artery a...
Pulmonary mycobacterium parascrofulaceum infection results from infection by the species Mycobacterium parascrofulaceum, which is a relatively new species of non-tuberculous mycobacterium (NTM) belonging to group 2. Infection by this species is rare and infrequently reported and the lung is cons...
Radiation therapy has the potential to cause complications in many organ systems, many of which, especially in the thorax, are important for radiologists to be aware of.
acute radiation syndrome
complications of cranial radiation therapy
radiation-induced cerebral vasculopathy
Desmoplastic small round cell tumor (DSRCT) of the pleura is a rare primary pleural malignancy comprising of mesenchymal cells.
Tend to occur in younger patients (mean ~ 25.5 years) and with a slightly greater male predilection.
Treatment and prognosis
DSRCT tend to be aggressi...
The term ground glass may be used to refer to:
ground glass opacity (lungs)
ground glass matrix of fibrous dysplasia
The list of differential diagnoses for miliary lung nodules can be recalled with the mnemonic:
E: eosinophilic granuloma
M: metastases (especially thyroid)
E: extrinsic allergic alveolitis (now known as hypersensitivity pneumonit...
The superior triangle sign is seen with complete right lower lobe (RLL) collapse alone or combined with right middle lobe collapse on PA chest x-rays. This sign can be a useful indirect sign of right lower lobe collapse where typical features are absent.
Free-standing bronchiectasis or non-traction bronchiectasis is a descriptive term for bronchiectasis that is not related to regional fibrotic effects (e.g. traction bronchiectasis). Amongst other causes, this form may occur in recurrent chronic infective-inflammatory states such as in those with...
N-butyl-2-cyanoacrylate pulmonary embolism is a potentially life-threatening complication that can arise following the use of the tissue glue, butyl-cyanoacrylate, for endoscopic sclerotherapy to treat variceal bleeding.
Sclerosis with biological glue (butyl cyanoacrylate) is curr...
Pulmonary hypertension associated with chronic obstructive pulmonary disease (PH-COPD) can be a common complication of chronic obstructive pulmonary disease and usually manifests as mild to moderate pulmonary hypertension in those with advanced COPD. Pulmonary arterial pressures in this situatio...
Bronchocentricity (or bronchocentric distribution) describes a process in the lungs that is centered around bronchi (or bronchioles). The term centrilobular is commonly used for peribronchiolar disease. Because of the parallel relationship of bronchi and pulmonary arteries these processes are al...
Fibrotic hypersensitivity pneumonitis (fHP) is is a chronic, often progressive fibrosing form of hypersensitivity pneumonitis and is also often categorized at a form of interstitial lung disease. Manifestations previously categorized as chronic hypersensitivity pneumonitis now fall under this ca...
Rapidly progressive pneumoconiosis (RPP) is termed a form of pneumoconiosis when the condition shows an increase in chest radiograph profusion by one ILO subcategory in less than 5 years 1.
Conditions than can fall into this category include
Pulmonary cladophialophora infections are a form of rare pulmonary fungal infection caused by Cladophialophora spp. such as
Cladophialophora is a genus of fungi in the family Herpotrichiellaceae with around 35 species described.
Collagen vascular disease-related interstitial pneumonitis (CVD-IP) refers to a subgroup of interstitial lung disease that is associated with collagen vascular disease.
Some estimate that up to 15% of patients presenting for evaluation of interstitial lung disease may have an unde...
Upper lobe fibrocavitary pattern of mycobacterium avium complex pulmonary disease is morphological from pulmonary mycobacterium avium complex infection although it is worthwhile understanding that there can be a spectrum of the disease with mixed forms.
This form had been initially the traditi...
Contraceptive implant migration is a rare complication of etonogestrel implant insertion.
unable to palpate device in the upper arm
irregular vaginal bleeding
Contraceptive implants are most commonly in...
A sliding hiatus hernia or type 1 hiatus hernia is considered the most common type of hiatus hernia. They can be present to varying degrees and can also co-exist with other types (inclusive of a rolling hiatus hernia).
Many patients may have gastro-esophageal reflux. Some...
Rheumatoid arthritis associated interstitial lung disease (RA-ILD) is one of the pulmonary manifestations of rheumatoid arthritis.
There may be a greater male predilection with onset of lung disease typically occurring in the 5th to 6th decades of life 5.
Pulmonary valve calcification is an uncommon occurrence and usually occurs in the presence of longstanding elevation of right ventricular pressures (such as that of severe pulmonary hypertension). It can also be associated with pulmonary valve stenosis. Some authors suggest if valve calcificatio...
Tuberculous bronchostenosis is a potential complication that can occur from endobronchial tuberculosis, especially in a chronic form.
Bronchostenosis usually begins as simple erythema and edema with lymphocytic submucosal infiltration followed by tubercle formation. Destruction and r...
A mnemonic to remember the radiographic signs of pulmonary edema is:
A: alveolar opacification
D: diffuse interstitial thickening (septal lines) and diversion (vascular upper zone diversion, cephalisation)
E: effusions (pleural)
The characteristic shape of the crescent has been given to many radiological signs over the years.
crescent sign (disambiguation)
crescent sign (arterial dissection)
crescent sign (inguinal hernia)
crescent sign (intravenous pyelogram)
crescent sign (lung hydatid)
crescent sign (osteonecro...
Iodinated oil pulmonary embolism is a form of particulate material pulmonary embolism which in turn falls under non-thrombolic pulmonary emboli. Iodinated oil pulmonary embolism occurs in the setting of:
oily chemoembolisation of tumors
hepatocellular carcinoma 1,3
The lateral thoracic vein (TA: vena thoracica lateralis) is a tributary of the axillary vein. It provides venous drainage for the axilla, anterolateral chest wall, including serratus anterior and pectoralis muscles and breast, and the supraumbilical abdominal wall.
In some texts, t...
Unicentric Castleman disease (UCD) is considered the more common form of Castleman disease and involves one or more enlarged lymph nodes in a single region of the body that demonstrates histopathologic features that have features of Castleman disease. A subset of patients can have systemic symp...
A dependent contrast level within the inferior vena cava is a situation that can be observed in some cases with inferior vena caval contrast reflux. Its presence is usually associated with very poor cardiac output and can be accompanied by dependent layering of venous refluxed contrast within th...
Reflux of contrast into inferior vena cava can be common findings seen on CT. It is considered a specific but insensitive sign of right-sided heart disease / right heart dysfunction at low contrast injection rates although the usefulness decreases with high injection rates.
A tuberculous pleural effusion is one of the manifestations of pleural tuberculosis. It can have variable presentation ranging from a largely benign pleural effusion, with potential to completely resolve to a complicated effusion with loculations, pleural thickening and potentially progressing t...
Pleural tuberculosis refers to various manifestations of involvement of the pleura by Mycobacterium tuberculosis.
It manifests in various forms which include
tuberculous pleural effusion 3
Cameron lesions refer to linear ulcers or erosions that occur on the mucosal folds at the diaphragmatic impression of a hiatus hernia. They are usually radiographically occult and diagnosed endoscopically (although still useful for a radiologist to know).
Their prevalence has been...
Interstitial lung disease associated with primary biliary cholangitis can occur in a variable pattern that can include 1:
lymphoid interstitial pneumonia
non-specific interstitial pneumonia
bronchiolitis obliterans with organizing pneumonia
It may occur in a...
Long COVID-19, also known as post-acute sequelae of SARS-CoV-2 infection (PASC) or post COVID-19 condition, is a post-viral syndrome affecting people who have recovered from COVID-19 infection. Symptoms are similar to those experienced by patients with chronic inflammatory response syndrome (CIR...
Portable radiography (also known as mobile radiography) is frequently performed in hospitals when patients are too unwell to transport to the imaging department. However, most health facilities endeavor to perform "departmental films", as image quality tends to be inferior when performed with a ...
Esophageal temperature probes are used to monitor core body temperatures in patients receiving anesthesia. The probe is advanced either through the nasal passage or oral cavity, before following a similar path to a nasogastric tube.
Clinically significant changes in core body tempe...
Focal ground glass opacification refers to relatively contained area of ground glass although these can be multiple and can involve more than one contiguous part of the lungs.
These can include:
distinct nodules - ground glass density nodules
pure ground glass nodules
amorphous non nodular g...
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.
Most cases are diagnosed in childhood 1.
Pembrolizumab induced pneumonitis is a form of drug-induced lung disease occurring as a result of a response to the use of the programmed cell death protein 1 (PD1) inhibitor pembrolizumab. It may have variable pattern 2.
Pembrolizumab is also reported to have a high risk of inducing lung inju...
Pulmonary zygomycosis was previously used term for an umbrella of pulmonary fungal species causing pulmonary fungal infection which is now superseded by terms such as pulmonary mucormycosis according to more recent publications. Previously some publications have used two terms as synonymous.
Lymphangiomatosis is a rare mesenchymal disorder that is characterized by developmental "malformation" of multiple lymphatic channels (usually with dilatation).
If lymphatic channels are purely dilated and not malformed the term lymphangiectasia is usually used. If lymphangiomatosi...
The aerodigestive tract is a non-TA descriptive collective term for the respiratory tract and proximal portion of the digestive tract. As it is a non-standard term, its precise components vary somewhat with the context in which the term is being employed.
Definitions of what precis...
Crizotinib associated interstitial pneumonitis is a type of drug-induced lung disease precipitated by a tyrosine kinase/anaplastic lymphoma kinase (ALK) inhibitor Crizotinib used in the treatment of certain forms of non-small cell lung cancer that have certain mutations including the ROS1 mutati...
Pyothorax-associated lymphoma (PAL) is a non-Hodgkin lymphoma of exclusively B-cell phenotype that develops in the pleural cavity of patients after a long-standing pyothorax or empyema.
There is a strong association with EBV infection.
A mnemonic to remember the commonest causes of cavitating lesions seen in a chest x-ray is:
W: Wegener's granulomatosis (granulomatosis with polyangiitis)
E: embolism (pulmonary, septic)
I: infection (anaerobes, pneumocystis, TB)
R: rheumatoid arthritis (necrobiotic no...
Tobacco abuse, most commonly by smoking cigarettes, is a legal drug habit of many throughout the world. It is a significant risk factor for many malignancies, respiratory and cardiovascular diseases and is a major cause of premature mortality throughout the world.
It has been esti...
The Neer impingement test is a clinical test to aid the diagnosis of rotator cuff impingement. It predominantly provokes a posterosuperior internal impingement mechanism and involves forward flexion of the arm with the thumb facing down with the arm in a more anterolateral orientation.
Anectasis is a term that describes primary atelectasis, as distinct from secondary atelectasis.
Anectasis refers to the failure of the lung to expand fully at birth.
Ventilator-induced lung injury (VILI) is a type of acute lung injury usually inflicted or aggravated by mechanical ventilation. It may occur during invasive or non-invasive ventilation.
The predominant mechanisms include:
alveolar overdistention (volutrauma) / regional lung overdist...
Kussmaul sign is a clinical sign, seen as a paradoxical increase in the jugular venous pressure in response to inspiration. This is opposed to the normal physiological response of inspiration resulting in decreased jugular venous pressure 1.
This sign typically arises secon...
Acute lung injury (ALI) refers to a rather broad clinical syndrome defined by a constellation of clinical criteria which includes:
acute onset of bilateral pulmonary infiltrates
without evidence of hydrostatic pulmonary edema
pulmonary wedge pressures of usually 18 mmHg or les...
Bullous sarcoidosis is a rarely described pattern in pulmonary sarcoidosis where there is concurrent presence of bullous emphysema superimposed on the typical changes of sarcoidosis. It may be contributed by fibrotic cysts, bullae, and paracicatricial emphysema from traction effects or endobronc...
It is important to be able to distinguish between mucormycosis and aspergillosis because:
antifungal sensitivity: mucormycosis is resistant to voriconazole, whilst aspergillosis is sensitive to it
mucormycosis may have an improved prognosis if treated earlier
It is to be noted that there has...
Mixed germ cell tumors of the mediastinum or mediastinal mixed germ cell tumors are malignant non-seminomatous germ cell tumors of the mediastinum consisting of more than one type of germ cell tumor.
The term ‘malignant teratoma’ is not recommended.
Mixed germ cell t...
The right ventricular fractional area change is a two-dimensional measure of right ventricular global systolic function usually made on an echocardiogram. It is obtained from the apical four-chamber view and is calculated as
RV- fractional area change = (end-diastolic area - end-systolic area) ...
Aerogenous metastases are a rare form of metastases that can occur in the lung due to aerogenous spread along the airways.
It is related to but not considered identical to the term spread through air spaces (STAS) 4.
Aerogenous metastases are usually from primary lung cancer dissemi...
Tularemia is a rare and highly virulent febrile zoonotic bacterial infection caused by Francisella tularensis, which has been developed as a bioweapon by several countries. It can infect the skin and mucous membranes, lungs and intestine and cause systemic disease and death. Tularemia is a notif...
Mediastinal choriocarcinomas or choriocarcinomas of the mediastinum are malignant non-seminomatous germ cell tumors of the mediastinum consisting of trophoblastic cells.
Pure choriocarcinomas are rare and account for up to 3% of primary mediastinal germ cell tumors 1. They usually...
Mediastinal embryonal carcinomas or embryonal carcinomas of the mediastinum are malignant non-seminomatous germ cell tumors with embryonal type cells primarily growing in the mediastinum.
Mediastinal embryonal carcinomas are very rare mediastinal tumors accounting for up to 8% of ...
Mediastinal yolk sac tumors or yolk sac tumors of the mediastinum are malignant non-seminomatous germ cell tumors primarily growing in the mediastinum.
The term ‘endodermal sinus tumor’ is not recommended.
Mediastinal yolk sac tumors are rare mediastinal tumors. In a...
Mediastinal seminomas or mediastinal germinomas are primary malignant germ cell tumors of the mediastinum.
Mediastinal seminomas are rare mediastinal tumors and account for up to one-third of primary malignant mediastinal germ cell tumors 1. They are almost only found in males ≥10...
The trigonum parietale refers to a triangular opacity seen on chest radiograph that correlates with a small piece of extrapleural areolar tissue that lies between the layers of pleura in the fissure of an azygos lobe 1-4. It may be seen at the most superior portion of the azygos fissure and shou...
An absent azygos vein is a very uncommon variant in which the azygos vein fails to develop. In cases of agenesis of the azygos vein, the hemiazygos and accessory hemiazygos veins play an important role in venous drainage, accounting for drainage of both the right and left intercostal veins 1-3.
Gastropericardial fistulas are rare abnormal communications between the stomach and the pericardial sac. This is a life-threatening condition that can lead to impaired cardiac function, sepsis and eventually death.
Patients with gastropericardial fistula may present with ...
A mediastinal lipoma is a benign fat-containing mediastinal lesion.
Similar to lipomas elsewhere and except in rare situations comprise of mature adipocytes. They can be variable in size. They are usually seen as an encapsulated mass with homogeneous fat attenuation. These lesions oc...
The bronchomediastinal trunks (a.k.a. bronchomediastinal lymphatic trunks) are lymphatic trunks, one on each side of the body. On the left, the bronchomediastinal trunk is a tributary of the thoracic duct, and on the right, it is a tributary of the right lymphatic duct. Although, in some individ...
Blunting of the costophrenic angle (also known as blunting of the costophrenic sulcus) is a chest radiograph sign usually indicative of a small pleural effusion. It may be seen on either frontal or lateral erect projections. It has been found that approximately 200 mL pleural fluid needs to be p...
The CT chest-abdomen-pelvis protocol serves as an outline for an examination of the trunk covering the chest, abdomen and pelvis. It is one of the most common CT examinations conducted in routine and emergencies. It can be combined with a CT angiogram.
Note: This article aims to frame a genera...
The bird’s nest sign refers to the appearance created by a reverse halo sign with associated irregular and intersecting areas of stranding or irregular lines within the area of ground-glass opacity 1.
Both bird's nest sign and reverse halo signs are suggestive of invasive pulmonary fungal infec...
Cartilage or cartilaginous tissue is a resilient and type of connective tissue of mesodermal origin that forms an integral part within the musculoskeletal system and as a structural component in other organs.
Cartilage can be generally classified into the following main types:
A diaphragmatic lung hernia (plural: hernias or herniae) is extremely rare, characterized by a lung herniation through the diaphragm into the abdominal cavity. There has been a single case report 2. It is questionable whether this entity truly exists at all 3.
This is not to be confused with th...
Cervical lung hernias (alternative plural: herniae), also known as apical lung hernias, are a subtype of lung hernias in which lung protrudes through the apex of the thoracic cavity.
Lung herniation of any form is rare. Cervical lung hernia is thought to represent only ~20% lung h...
Compensatory lung hyperinflation (a.k.a. compensatory lung overinflation) is a situation in which due to loss of volume of a lung, unaffected parts of the same lung overinflate as compensation. In more severe cases, the contralateral lung may also overinflate with possible mediastinal shift towa...