Acute disseminated encephalomyelitis (ADEM), as the name would suggest, is featured by a monophasic acute inflammation and demyelination of white matter typically following a recent (1-2 weeks prior) viral infection or vaccination 4,6. Grey matter, especially that of the basal ganglia, is also o...
Acute eosinophilic pneumonia (AEP) is a type of eosinophilic lung disease. It is diagnosed when the following combination clinical and radiographic findings occur 5,7:
febrile illness of less than five days' duration
diffuse alveolar or mixed alveolar-interstitial opacities on ches...
Acute fatty liver of pregnancy (AFLP) is a rare pregnancy-associated condition that tends to manifest in the 3rd trimester of pregnancy or early postpartum period.
The estimated incidence is at around 1:7000-20,000 births.
Patients may present with nausea,...
Acute gastritis is a broad term that encompasses a myriad of causes of gastric mucosal inflammation.
Depends on the aetiology (see below).
nausea and vomiting
loss of appetite
infection: H. ...
Acute haemorrhagic encephalomyelitis (AHEM), also known as acute haemorrhagic leukoencephalitis (AHLE), Hurst disease or Weston-Hurst syndrome, is a very rare form of demyelinating disease. It occurs sporadically and may be considered as the most severe form of acute disseminated encephalomyelit...
Acute hepatitis occurs when the liver suffers an injury with a resulting inflammatory reaction. The cause of the injury can occur in multiple different ways, and imaging findings are often non-specific. Ultrasound and MRI may be useful imaging modalities to suggest the diagnosis, but often the d...
Acute hypersensitivity pneumonitis (AHP) refers to the acute form of hypersensitivity pneumonitis although this classification system has recently been challenged 4. For a general discussion of the condition, refer to the parent article.
Fever, chills, myalgia, headaches,...
Acute idiopathic scrotal oedema (AISE) is a self-limiting condition characterised by marked oedema of the skin and dartos fascia without involvement of the deeper layers, testes, or epididymis. It is an important condition to recognise in order to avoid unnecessary surgical exploration.
Acute interstitial pneumonitis (AIP), also known as Hamman-Rich syndrome is a rapidly progressive non-infectious interstitial lung disease of unknown aetiology. It is considered the only acute process among the idiopathic interstitial pneumonias.
Truly idiopathic AIP tends to occu...
Acute invasive fungal sinusitis is the most aggressive form of fungal sinusitis. It is seen particularly in immunocompromised patients and is the source of significant morbidity and mortality. It should be distinguished from the other two forms of invasive fungal sinusitis, chronic invasive fung...
Acute liver failure (ALF), or fulminant hepatic failure (FHF), refers to sudden severe liver dysfunction from injury without underlying chronic liver disease (CLD), although sometimes ALF presents as decompensation of an unknown CLD.
ALF is rare, with < 1 case per 100,000 in the ...
Acute lung transplant rejection is one of the post lung transplant complications. Histologically, it is defined as perivascular or peribronchiolar mononuclear inflammation and may affect up to 55% of lung transplant recipients within the first year after a transplant 2.
It can oc...
Acute mastoiditis is largely a disease of childhood and occurs when acute otitis media extends into the mastoid air cells.
When mastoiditis and acute otitis media occur concurrently, sometimes the term acute otomastoiditis is used.
When mucoperiosteal involvement evolves into bo...
Acute necrotic collections (ANCs) are an early, local complication of necrotising pancreatitis.
The following are the latest terms according to the updated Atlanta classification to describe fluid collections associated with acute pancreatitis 1,2:
fluid collections in interstitia...
Acute necrotising encephalitis of childhood (ANEC) is a rare type of encephalopathy characterized by multiple bilateral brain lesions, mainly involving the thalami, but also the putamina, internal and external capsules, cerebellar white matter, and the brainstem tegmentum.
Acute otitis externa (AOE), also known as "swimmer's ear", is inflammation of the external auditory canal (EAC) that can involve the pinna as well. Bacterial infection, most commonly with Pseudomonas aeruginosa, is responsible for the overwhelming majority of cases. It is a common condition.
Acute pancreatitis is an acute inflammation of the pancreas and is a potentially life-threatening condition.
The diagnosis of acute pancreatitis is made by fulfilling two of the following three criteria 8:
acute onset of persistent, severe epigastric pain (i.e. pain consistent with acute pancr...
Acute pancreatitis refers to acute inflammation of the pancreas and is a potentially life-threatening condition.
This is a summary article; read more in our article on acute pancreatitis.
epidemiology is dependent on the cause of pancreatitis
Acute pelvic pain is a common presenting symptom to the emergency department and radiologist. Pelvic ultrasound with transabdominal and endovaginal approaches is usually the first line imaging modality.
pain of <3 months duration
Patients also often pres...
Acute peripancreatic fluid collections (APFC) are an early complication of acute pancreatitis that usually develop in the first four weeks. After four weeks, the term pseudocysts is used. The absence of necrosis differentiates APFCs from acute necrotic collections (ANC), that is, APFCs occur in ...
Acute pyelonephritis is a bacterial infection of the renal pelvis and parenchyma most commonly seen in young women. It remains common and continues to have significant morbidity in certain groups of patients.
The incidence of acute pyelonephritis parallels that of lower urinary tr...
Acute respiratory distress syndrome (ARDS) is a form of acute lung injury (ALI) 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.
Acute right heart syndrome (ARHS) is defined as a sudden deterioration in right ventricular (RV) function and failure of the RV to deliver adequate blood flow to the pulmonary circulation. This can result in systemic hypoperfusion.
ARHS can occur in several settings 1
in the setting...
Acute sinusitis is an acute inflammation of the paranasal sinus mucosa that lasts less than four weeks and can occur in any of the paranasal sinuses. If the nasal cavity mucosa is also involved then the term rhinosinusitis may be used.
Fever, headache, postnasal discharge...
Acute spinal cord ischaemia syndrome (ASCIS) is uncommon, but usually presents with profound neurological signs and symptoms, and the prognosis is poor.
Acute spinal cord ischaemia syndrome represents only 5-8% of acute myelopathies 4,5 and <1% of all strokes 7. The demographic o...
Acute superior mesenteric artery occlusion, which can then result in an acute mesenteric ischaemia, can be a life-threatening event related to the artery supplying the majority of the small bowel and right side of the colon.
An acute occlusion is an uncommon event that typically...
Acute superior mesenteric vein thrombosis is one of the less common causes of intestinal ischaemia.
For a general discussion refer to intestinal ischaemia.
Compared to acute superior mesenteric artery occlusion or ischaemia secondary to small bowel obstruction, acute superior me...
Acute unilateral airspace opacification is a subset of the differential diagnosis for airspace opacification.
The exhaustive list of all possible causes would be huge, but a useful framework includes :
pus, i.e. infection
Differentiating between acute and chronic infarction on a CT brain is an important skill for many health professionals particularly in the emergency setting:
acute: cytotoxic oedema
chronic: encephalomalacia; Wallerian degeneration
acute: more dense than CSF
Acyanotic congenital heart disease comprises numerous aetiologies, which can be divided into those with increased pulmonary vascularity (pulmonary plethora) and those with normal vascularity:
increased pulmonary vascularity
ventricular septal defect (VSD)
atrial septal defect (ASD)
The Adam's forward bend test is clinical test to assess the presence of a scoliosis.
Exclusion of a limb length discrepancy is considered important prior to performing the test. The patient is asked to bend forward with feet together, arms hanging and knees extended until the back be...
Adamantinomas are rare primary malignant bone tumours that in the vast majority of cases occur in the tibia of young patients.
In the past, ameloblastomas, which are benign, locally aggressive bone tumours of the mandible, were also known as adamantinomas of the mandible. The two e...
The Adams-Oliver syndrome (AOS) is a rare disorder characterised by aplasia cutis congenita (missing hair and/or skin) and variable degrees of terminal transverse limb defects.
polymicrogyria: can be associated with a variant of Adams-Oliver syndrome 3
ADC pseudonormalisation is a normal phase encountered in the subacute stage of ischaemic stroke and represents an apparent return to normal healthy brain values on ADC maps which does not however represent resolution of ischemic damage.
ADC pseudonormalisation is seen typically between around 1...
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The adductor brevis is a muscle in the medial compartment of the thigh that lies immediately deep to the pectineus and adductor longus.
origin: external surface of body of pubis and inferior pubic ramus
insertion: posterior surface of proximal femur, linea aspera, medial supracondylar...
The adductor canal is a muscular tunnel in the thigh. It commences at the inferior end of the femoral triangle and terminates at the adductor hiatus.
anteriorly: sartorius muscle
posteromedially: adductor longus and adductor magnus muscles
laterally: vastus mediali...
The adductor hallucis muscle arises by two heads, an oblique and transverse head. It is responsible for adducting the big toe.
transverse head: ligaments associated with metatarsophalangeal joints of lateral three toes
oblique head: bases of metatarsals II to IV and from sheat...
The adductor longus is a muscle in the medial compartment of the thigh that lies anterior to the adductor magnus.
origin: external surface of body of pubis (triangular depression inferior to pubic crest and lateral to pubic symphysis)
insertion: linea aspera on middle one-third of sh...
The adductor magnus is the largest and deepest of the muscles in the medial compartment of the thigh. Like the adductor longus and brevis muscles, the adductor magnus is a triangular or fan shaped muscle anchored by its apex to the pelvis and attached by its expanded base to the femur.
The adductor pollicis is a large triangular muscle anterior to the plane of the interossei that crosses the palm.
transverse head: 3rd metacarpal
oblique head: capitate and bases of 2nd and 3rd metacarpals
insertion: base of proximal phalanx and extensor hood of thumb
Adenocarcinoma of the endometrium is the commonest histological subtype of endometrial cancer and accounts for up to 90% of such cases 1.
Histological sub types
serous type adenocarcinoma of the endometrium
clear cell type adenocarcinoma of the endometrium
Adenocarcinoma of the urinary bladder is rare and accounts for only ~1% of all bladder cancers (90% are transitional cell carcinomas).
Metaplasia of urinary bladder induced by chronic irritation or infection can lead to adenocarcinoma. Pathological types of adenocarcinoma of the urin...
Adenocarcinoma in situ (AIS) of the lung refers to a relatively new entity for a pre-invasive lesion in the lung. This entity partly replaces the noninvasive end of the previous term bronchoalveolar carcinoma. Adenocarcinoma in situ is defined as a localised adenocarcinoma of <3 cm that exhibits...
Adenocarcinoma in situ, minimally invasive adenocarcinoma and invasive adenocarcinoma of the lung are relatively new classification entities which replace the now-defunct term bronchoalveolar carcinoma (BAC).
In 2011 the International Association for the Study of Lung Cancer (IASLC) and several...
Adenocarcinoma of the appendix, also referred to as nonmucinous adenocarcinoma of the appendix, is an uncommon type of appendiceal epithelial neoplasm. Different from the appendiceal mucinous neoplasms, these tumours share similar epidemiology and pathology with colorectal adenocarcinoma.
Adenocarcinoma of the cervix is a histological subtype of carcinoma of the cervix.
Cervical adenocarcinoma is less common than squamous cell carcinomas (SCC) of the cervix, accounting for ~12.5% of all cervical cancer. Their proportionate prevalence is thought to be increasing an...
Duodenal adenocarcinoma is the most common primary malignancy of the duodenum.
Adenocarcinoma is the most common primary malignant neoplasm of the duodenum. It represents 0.3% of all gastrointestinal malignancies and accounts for 50-70% of small bowel adenocarcinomas occurring ei...
Adenocarcinoma of the lacrimal glands is rare, with few cases reported in the literature since it was first described in 1996 1. Primary adenocarcinoma of the lacrimal gland is extremely rare; only 9 cases have been reported in the literature 1,2. It can be classified into high- and low-grade ma...
Adenocarcinoma of the lung is one of the non-small cell carcinomas of the lung and is a malignant tumour with glandular differentiation or mucin production. This tumour exhibits various patterns and degrees of differentiation, including lepidic, acinar, papillary, micropapillary, and solid with ...
Primary adenocarcinoma of the small bowel is about 50 times less common than colonic carcinoma.
Almost 50% of small bowel adenocarcinomas are found in the duodenum, especially near the ampulla. In the remaining cases, the jejunum is more commonly involved than the ileum1.
Adenoid cystic carcinomas are a rare histological subtype of adenocarcinoma.
Adenoid cystic carcinomas are generally considered low grade 4. The tumours have a notable tendency for perineural spread.
They have a wide distribution and mainly occur in relation to the airways...
Adenoid cystic carcinoma (ACC) of the lacrimal glands is an extraconal malignancy usually originating from the orbital lobe of the lacrimal gland.
It often presents with orbital pain and paresthesia, since this type of tumour is frequently associated with perineural sprea...
Adenoid cystic carcinoma (ACC) of the lung is a type of non-small cell lung cancer. They are classified under lung carcinomas of the salivary gland type. Primary occurrence in the lung parenchyma is rare, while in the thorax they occur more commonly as adenoid cystic carcinoma of the tracheobron...
Adenoid cystic carcinoma (ACC) of the breast is a rare subtype of breast cancer.
They account for only 0.1-0.4% of all breast cancers.
The tumour demonstrates a strikingly characteristic microscopic pattern similar to that of adenoid cystic carcinoma of the salivary gl...
Adenoid cystic carcinoma (ACC) of the salivary glands is the most common malignancy involving the minor salivary glands and the second most common malignancy involving the parotid gland.
Adenoid cystic carcinomas arise more commonly in the minor salivary glands (~55%) than in the maj...
Adenoid cystic carcinomas of the tracheobronchial tree are a type of low-grade tracheal tumour. They are considered to be the second most common primary tumour of the trachea.
They are usually first recognised in patients in their 4th and 5th decades. There is no recognised gender...
Adenoid facies, also known as the long face syndrome, refers to the long, open-mouthed face of children with adenoid hypertrophy. Hypertrophy of the nasopharyngeal pad of lymphoid tissues (adenoids) is the most common cause of nasal obstruction in children. The mouth is always open because upper...
Adenoidal hypertrophy or enlargement is common in childhood and is due to an increase in the size of the adenoids.
nasal congestion: adenoid facies
chronic or recurrent otitis media due to their proximity to the Eustachian tubes
Adenolipoma of the thyroid gland (also known as a thyrolipoma or a thyroid hamartoma) is a rare, benign fat-containing thyroid lesion. These lesions are usually well encapsulated and are composed of varying degrees of follicular thyroid tissue (thyroid adenoma) and mature adipose tissue; the amo...
Adenoma malignum of the cervix, also referred to as minimal deviation carcinoma / minimal deviation adenocarcinoma, is considered a rare variant of cervical carcinoma. It is thought to represent ~1-3% of all cervical adenocarcinomas.
It can present in a wide age group (~25-70 year...
The adenoma-carcinoma sequence refers to a stepwise pattern of mutational activation of oncogenes (e.g. K-ras) and inactivation of tumour suppressor genes (e.g. p53) that results in cancer. An oncogene is a gene that has the potential to cause cancer. In tumour cells, these are often mutated or ...
Adenomatoid odontogenic tumours are rare and differ from most other dentition related lesions in that they more frequently occur in the maxilla.
They are also seen more frequently in females, most frequently in the second decade of life.
They present as an ...
Adenomatoid tumours of the scrotum are benign, solid extra testicular lesions that can originate from the epididymis, tunica vaginalis, or spermatic cord (90% derived from the funiculus).
They are the most common extra testicular neoplasm, and most common tumour of the epididymis,...
Adenomatous breast lesions are benign tumors which grow from glandular parenchyma. The breast is a conglomeration of various glandular tissues, hence they can be of several types.
apocrine adenoma of breast
pleomorphic adenoma of breast
Adenomatous endometrial hyperplasia is a type of endometrial hyperplasia.
The peak incidence is around 40-50 years of age.
Both endogenous and exogenous oestrogen exposure are considered important factors in its aetiology 1.
An adenomyoma is a focal region of adenomyosis resulting in a mass, which is difficult to distinguish from a uterine fibroid, although in general the degree to which the contour of the uterus is distorted is less marked in adenomyosis 2. Additionally, the 'mass' is poorly defined and blends with...
Adenomyomatosis of the gallbladder is a hyperplastic cholecystosis of the gallbladder wall. It is a relatively common and benign cause of diffuse or focal gallbladder wall thickening. It is most easily seen on ultrasound and MRI.
Adenomyomatosis is relatively common, found in ~9%...
Adenomyosis of the uterus is a common, benign uterine pathology. It is thought by many to be on the spectrum of endometriosis, with ectopic endometrial tissue in the myometrium. Adenomyosis may present with menorrhagia and dysmenorrhea. Ultrasound and MRI are imaging modalities that may show cha...
An adenomyotic cyst is an extremely rare variation of cystic adenomyosis. The lesion consists of a large hemorrhagic cyst, which is partly or entirely surrounded by a solid wall. It can be entirely within the myometrium, submucosal, or subserosal and frequently is associated with symptoms of men...
Adenosis of the breast is a benign lobulocentric proliferative process in which lobules are enlarged and increased in number in addition to an increased number of glands within each lobule.
Pathologically subclassified into three main subtypes which include:
sclerosing adenosis of the breast
Adenosquamous cell carcinoma (ASC) of the cervix is a rare histological subtype of cervical carcinoma.
It has components of both cervical adenocarcinoma and cervical squamous cell carcinoma.
An adenosquamous histology appears to be an independent predictor of poor outcome...
Adenosquamous carcinoma of the endometrium is a rare histological sub type of endometrial cancer.
In general it occurs in a slightly younger group when compared with pure adenocarcinoma of the endometrium 4.
It contains both malignant glandular and malignant squamous components. Adenosquamous...
Adenosquamous carcinoma (ASC) of the lung is a rare type of non-small cell lung cancer.
It is thought to constituting 0.4-4% of cases non-small cell lung cancer.
The definition of adenosquamous carcinoma indicates a carcinoma showing components of adenocarcinoma and sq...
Adhesive capsulitis of the shoulder, also known as frozen shoulder, is a condition characterised by thickening and contraction of the shoulder joint capsule and surrounding synovium. Adhesive capsulitis can rarely affect other sites such as the ankle 8.
The incidence in the genera...
Adie pupil (also known as tonic pupil) is caused by idiopathic degeneration of the ciliary ganglion, which sometimes occurs following a viral or bacterial illness. It is usually unilateral and typically affects young females 1.
Adie pupil represents a large dilated "tonic pupil", which does not...
Adie syndrome was named after the British physician and neurologist William John Adie (1886 - 1935).
It consists of a classic triad of:
absent deep tendon reflexes, e.g. ankle jerk
an Adie pupil: tonically dilated and responds poorly or not at all to light
It is thought to res...
The ADIR (ADduction and Internal Rotation) position relates to MR arthrography of the shoulder joint.
When added to a neutral-position shoulder protocol, MR arthrography in the ADIR position facilitates the diagnosis of labroligamentous lesions in patients with recurrent shoulder dislocations, ...
Adnexa (pl., sing. adnexus) is a general term that refers to the accessory structures of an organ. In general radiological use, the term is often (incorrectly) used synonymously with ovary, an adnexal structure of the uterus.
Adnexa have been described with:
uterus (adnexa uteri)
The term adnexal torsion refers to torsion of the pelvic adnexal structures. This can encompass ovarian torsion + / - tubal torsion.
Adrenal adenomas are the most common adrenal mass lesion and are often found incidentally during abdominal imaging for other reasons. In all cases, but especially in the setting of known current or previous malignancy, adrenal adenomas need to be distinguished from adrenal metastases or other ad...
The adrenal glands are supplied by three adrenal (suprarenal) arteries:
superior adrenal artery: arises from ipsilateral inferior phrenic artery
middle adrenal artery: arises from lateral side of abdominal aorta
inferior adrenal artery: arises from the ipsilateral renal artery
Adrenal calcification is not a rare finding in healthy asymptomatic people and is usually the result of previous haemorrhage or tuberculosis. Addison's disease patients only occasionally have calcification.
sepsis: Waterhouse-Friderichsen syndrome
An adrenal collision tumour or collision tumour of the adrenal gland is an uncommon condition where two histologically distinct tumours abut each other or are in close proximity in the same adrenal gland.
Collision tumours have been reported in nearly every organ, for example, collis...
Primary adrenal cortical carcinoma is a highly malignant but rare neoplasm. It may present as a hormonally active or inactive tumour.
Although men and women are affected equally, functioning tumours are more common in females, who are also more likely to have an associated endocr...
Adrenal cysts are rare lesions and are commonly incidental findings.
Adrenal cysts are reported to be rare with an incidence of <1% 1.
Patients can present with pain or swelling, although a significant portion (~40%) are incidental findings 1,3.
The adrenal (suprarenal) glands are paired organs of the endocrine system, often asymmetric in shape.
Each gland is enclosed in the perirenal fascia and each has a body and two limbs: a medial limb and a lateral limb. However, the right adrenal gland is usually more pyramidal in...
Adrenal gland trauma most commonly results from blunt force trauma.
Adrenal gland trauma is present on 1-2% of CT imaging in blunt trauma although the occurrence is thought to be much higher as injury has been demonstrated at 28% in one autopsy series 1-4.
The right adrenal glan...
Despite its small size, the adrenal gland is affected by a relatively large number of neoplastic entities:
adrenal cortical carcinoma
adrenal lesions: for a more general list of...
Adrenal haemangiomas are rare benign tumours that are usually incidentally identified (one example of an adrenal incidentaloma). Its significance mainly relates to the difficulty in differentiation from other malignant lesions.
Although these can be found at any age, they are mos...
Adrenal haemorrhage can result from a variety of traumatic and non-traumatic causes. When unilateral, it is often clinically silent. In contrast, bilateral adrenal haemorrhage can lead to catastrophic adrenal insufficiency.
The large majority of patients with unilateral a...
Adrenal hyperplasia refers to nonmalignant growth (enlargement) of the adrenal glands and is a rare cause of ACTH-independent Cushing syndrome, with unilateral adrenal cortical adenomas being the commonest. 20% of Conn syndrome cases are secondary to adrenal hyperplasia. In diffuse hyperplasia, ...
Adrenal insufficiency refers to inadequate secretion of corticosteroids (glucocorticoids and mineralocorticoids).
It may occur from partial or complete destruction of the adrenal cortex, in which case it is termed primary adrenal insufficiency (also known as Addison disease). Secondary adrenal ...