There are many signs in radiology that are related to Christmas:
snowcap sign in avascular necrosis
in total anomalous pulmonary venous return
in pituitary macroadenomas
snowstorm appearance in complete hydatidiform and testicular microlithiasis
holly leaf sign in calcified pl...
Chronic bilateral airspace opacification is a subset of the differential diagnosis for airspace opacification. An exhaustive list of all possible causes of chronic bilateral airspace opacities is long, but a useful framework is as follows:
There are several viral and prion infections which can result in a chronic encephalitis with slow progression into brain atrophy. These have very poor prognosis with no effective treatment. Some of these include:
progressive multifocal leukoencephalitis
subacute sclerosing panencephalitis
Chronic interstitial pneumonitis is a broad descriptive term where an interstitial pneumonia has a prolonged course. It can arise of a range of aetiologies. The term does not usually imply a specific radiographic pattern and includes UIP, NSIP or other pattern. A a general rule there is little o...
Chronic primary adrenal insufficiency has a number of causes. Primary adrenal insufficiency is termed Addison disease.
idiopathic atrophy: autoimmune adrenalitis 1
tuberculosis 1: 25% calcify
fungal disease 1
Chronic unilateral airspace opacification is a subset of the differential diagnoses for airspace opacification. An exhaustive list of all possible causes of chronic unilateral airspace opacities is long, but a useful framework is as follows:
Clavicle tumours may be malignant or benign.
osteoma: uncommon, sclerotic, hamartomatous surface lesion
enchondroma: rare, geographic, intramed...
Cleft palate is a type of facial cleft. It can occur in two main aetiologically different forms:
in association with a cleft lip: cleft lip +/- palate (much commoner)
on its own: isolated cleft palate (rarer)
The differential of a mass involving or arising from the clivus is a relatively narrow one and can be divided into whether the lesion arises from the skull base itself, from the intracranial compartment or from below the base of skull.
When evaluating the clivus it is important to compare the...
Closed reduction or manipulation is a common non-invasive method of treating mildly displaced fractures. Usually performed in an emergency department or orthopaedic clinic with light sedation and analgesia, the fracture is manipulated back into anatomic alignment and immobilised with a cast, bra...
This article aims to be a collection of articles that represent the central nervous system infectious diseases. There will be some overlap between articles as they are listed and discussed in a mixture of anatomical and aetiological classification.
It is important to remember tha...
CNS lymphoma refers to the involvement of the central nervous system with lymphoma. It can be broadly divided into primary and secondary, with a number of special types of also recognised.
primary CNS lymphoma (PCNSL)
MALT lymphoma of the dura 5
secondary CNS lymphoma...
Coarse macrocalcifications within the breast are a morphological descriptive term for a type of breast calcification.
involuting fibroadenomas ( classical popcorn calcification )
chronic renal disease with hypercalcaemia 1
rarely seen in malignancy 2
invasive breast carci...
Coccydynia refers to pain in and among the area of the coccyx. It is characterised by coccygeal pain which is typically provocated by pressure. It may remain unclear in origin owing to the unpredictability of the source of pain 1.
No accurate data about the frequency of coccydynia...
Cochlear implants (CI) are a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing. Unlike conventional hearing aids, the cochlear implant does not amplify sound, but works by directly stimulating any functioning audi...
Codman triangle is a type of periosteal reaction seen with aggressive bone lesions. With aggressive lesions, the periosteum does not have time to ossify with shells of new bone (e.g. as seen in single layer and mulitlayered periosteal reaction), so only the edge of the raised periosteum will oss...
Coin lesion refers to a round or oval, well-circumscribed solitary pulmonary lesion. It is usually 1-5 cm in diameter and calcification may or may not be present 1,3. Typically but not always the patient is asymptomatic 1.
The differential diagnosis for such lesions is ...
COL4A1-related disorders are a group of autosomal dominant disorders caused by a mutation in the COL4A1 gene.
The exact prevalence is unknown, but the group of disorders is considered to be under-recognised, especially asymptomatic variants 1.
The clinical ...
Colonic strictures can be long (>10 cm) or short.
scirrhous colorectal carcinoma (apple core sign)
post surgical (anastamotic stricture)
scirrhous colorectal carcinoma
inflammatory bowel disease (IDB)
Colpocephaly is a descriptive term to a disproportionate prominence of the occipital horns of the lateral ventricles. It can result from a wide range of congenital insults.
Patient may present with motor abnormalities, cognitive deficit, visual abnormalities, and seizures...
Communicating hydrocephalus is a type of hydrocephalus where CSF is able to leave the ventricular system.
Communicating hydrocephalus is commonly used as the opposite of obstructive hydrocephalus which leads to much unnecessary confusion, as most causes of communicating hydrocepha...
Companion shadows are smooth, homogeneous, radiopaque shadows running parallel along the bones. They appear secondary to soft tissues and intercostal muscles running along:
inferior border of lower ribs
upper borders of clavicles
Companion shadows need to be diff...
There are many complications that can occur following gastric banding. It is helpful to divide these into early and late post-surgical complications.
Although the exact mode of presentation can vary depending on the underlying complication common modes of presentation tha...
Complications of cranial radiation therapy are fairly common, particularly in long term survivors, and especially in paediatric patients.
Cranial radiotherapy is used for a variety for a brain tumours, either in isolation or in combination with concurrent chemotherapy. Complications from irradi...
Complications of hip joint replacements are common and are essential for the radiologist to be aware in the assessment of the radiographs with hip prostheses. They are many and can occur at various time intervals following the initial surgery:
aseptic loosening: considered to be the most common...
Complications post optical colonoscopy are most commonly assessed by CT if patients present with abdominal symptoms post colonoscopy. Complications include:
bowel perforation (most common)
lower gastrointestinal haemorrh...
There are many conditions that can involve both skin and bone.
osteolytic bone lesions
basal cell naevus syndrome
langerhans cell histiocytosis
Conductive hearing loss is caused by a range of developmental, congenital or acquired pathology to the external, middle or inner ear.
Essentially any process that obstructs or disrupts the passage of sound waves through the outer or middle ear can cause conductive hearing loss and th...
Congenital adrenal hyperplasia (CAH) is a form of adrenal hyperplasia related to a variety of autosomal recessive disorders in adrenal steroidogenesis; characterized by low cortisol, low aldosterone and androgen excess.
virilization/genital ambiguity of female fetuses (d...
Congenital anomalies of the male urethra include various anomalies due to complex development of urethra. These anomalies can be isolated or in association with other coexisting anomalies.They can be categorised as following:
posterior urethral valve
anterior urethral valve...
Congenital calvarial defects are a group of disorders characterised by congenital calvarial bone defects that vary in severity.
CT with 3D shaded surface reformats is the best imaging tool as it demonstrates calvarial defects and bone margins:
Congenital limb amputations are a limb anomaly that usually occur due to disruption of vascular supply.
Congenital amputations occur in 0.5 (range 0.03-1) per 1000 live births 2.
Slightly more common in the upper limb (60%) than in the lower limb (40%) 2.
Congenital muscular dystrophies (CMD) are a heterogeneous group of autosomal recessive myopathies presenting at birth with hypotonia, delayed motor development, and early onset of progressive muscle weakness, confirmed with a dystrophic pattern on muscle biopsy.
Congenital renal anomalies comprise of vast spectrum of pathologies and include:
congenital renal hypoplasia
congenital cystic renal disease
infantile polycystic renal disease: autosomal recessive polycystic kidney disease (ARPKD):...
Congenital ventriculomegaly can have large number of syndromic associations
fetal alcohol syndrome
Congestive hepatopathy includes a spectrum of hepatic derangements that can occur in the setting of right-sided heart failure (and its underlying causes). If there subsequent hepatic fibrosis the term cardiac cirrhosis may be used. The condition can rarely occur as a result of non cardiac causes...
A contrecoup injury of the knee is a bone contusion of the posterior lip of the medial tibial plateau. It occurs during knee reduction after a pivot shift injury and is highly associated with ACL tears 1, and peripheral tear or meniscocapsular separation of the medial meniscus posterior horn 2.
Convexal subarachnoid haemorrhages (cSAH) are nontraumatic intracranial haemorrhages that occur within the surface sulci of the brain (c.f. basal cisternal distribution of aneurysmal SAH). There are various causes of convexal SAH, some of which include:
dural venous sinus thromboses
Cookie bite metastases are characterised by a small focal eccentric lytic external cortex destruction in long tubular bones.
This type destruction is typically described for metastases from bronchogenic carcinoma, however they can also occur with other tumours.
Coronal vertebral cleft refers to the presence of a radiolucent vertical defect on a lateral radiograph.
It is most often seen in premature male infants 1,3. As they can occur as part of normal variation (especially in the lower thoracic-upper lumbar spine of premature infants) ...
A coronary artery bypass graft (CABG or CAG) is placed during a surgical procedure to increase blood flow to the myocardium due to coronary stenoses, usually caused by coronary artery disease. Arteries or veins can be grafted during this procedure.
Long term outcome of coronary artery bypass gr...
Fractures of the coronoid process of the ulna are uncommon and often occur in association with elbow dislocation.
Fracture of the coronoid process is thought to result from elbow hyperextension with either avulsion of the brachialis tendon insertion, or shearing off by th...
Renal cortical nephrocalcinosis is ~20 times less common than medullary nephrocalcinosis.
renal cortical necrosis: common 2
toxaemia of pregnancy
extracorporeal shock wave lithotripsy (ESWL)
A coup-contrecoup injury is a term applied to head injuries and most often cerebral contusions and traumatic subarachnoid haemorrhage. It refers to the common pattern of injury whereby damage is located both at the site of impact (often less marked) and on the opposite side of the head to the po...
Cranioplasty is the surgical intervention to repair cranial defects, and is mostly performed after traumatic injuries. The procedure is performed using different materials and techniques, with no consensus about the best option. Methyl-methacrylate is the prosthetic material most extensively use...
Craniotomy is a surgical procedure where a piece of calvarial bone is removed to allow intracranial exposure. The bone flap is replaced at the end of the procedure, usually secured with microplates and screws. If the bone flap is not replaced it is either a craniectomy or cranioplasty.
Craniovertebral junction (CVJ) anomalies can be congenital, developmental or due to malformation secondary to any acquired disease process. These anomalies can lead to cranial nerve compression, vertebral artery compression and obstructive hydrocephalus.
The cranio-vertebral junctio...
Crazy paving refers to the appearance of ground-glass opacity with superimposed interlobular septal thickening and intralobular reticular thickening, seen on chest HRCT. It is a nonspecific finding that can be seen in a number of conditions.
Cricopharyngeal bar refers to the radiographic appearance of a prominent cricopharyngeus muscle contour on barium swallow.
The terms cricopharnygeal bar and cricopharyngeal muscle spasm/achalasia are often used synonymously but this is incorrect because studies have demonstrated th...
Crystal arthropathies are a group of joint disorders due to deposition of crystals in and around joints which lead to joint destruction and soft tissue masses.
The most common arthropathies are:
gouty arthropathy due to monosodium urate (MSU) deposition
pseudogout due to calcium py...
CSF otorrhoea is defined as leakage of cerebrospinal fluid (CSF) from the subarachnoid space into the middle ear cavity or mastoid air cells.
There are a number of underlying causes, and thus no specific demographic is affected.
Patients typically present ...
CT peritoneography is an examination used to assess difficulties with peritoneal dialysis.
Recurrent peritonitis with difficulty with fluid exchange abdominal wall or genital soft-tissue oedema, localized bulging of the abdomen, and poor ultrafiltration.
Cutaneous and subcutaneous metastases are uncommon, occurring in ~5% (range 0.7-10%) of internal malignancies. Sister Mary Joseph nodule is a well known cutaneous metastases.
These metastases can come from haematogenous or lymphatic spread, or may result from seeding from a surgical ...
Cutaneous calcifications in breast imaging can form in dermal sweat glands after low grade folliculitis and inspissation of sebaceous material. Calcifications may also form in moles and other skin lesions. The vast majority of calcifications are coincidental findings on mammography.
A number of entities can present as cyanotic congenital heart disease. These can be divided into those with increased or decreased pulmonary vascularity (pulmonary plethora):
increased pulmonary vascularity
total anomalous pulmonary venous return (TAPVR) (types I and II)
transposition of the ...
There is broad differential for cyst like lesions around the knee.
The list includes
popliteal synovial cyst - Baker's cyst
intra-articular ganglion cyst
ACL ganglion cyst
PCL ganglion cyst
Hoffa fat pad ganglion cyst
extra-articular ganglion cyst
Cystic or necrotic appearing lymph nodes can be caused by a number of infectious, inflammatory or malignant conditions:
squamous cell carcinoma metastases
plasmacytoid T-cell leukemia
acute myeloid leukemia
herpes simplex lymphadenit...
A cystic breast mass is a mass that contains both solid and fluid components. This can occur from both benign and malignant causes.
complex breast haematoma
complex breast abscess
breast cyst with associated inflammation and haemorrhage
fibrocystic changes and oil cysts...
Cystic hepatic metastases are included in the differential for new cystic liver lesions. The internal cystic component may represent necrosis as the tumor outgrows its hepatic blood supply, or it may represent a mucinous component, similar to the primary tumor.
The liver and lungs are the most ...
There several cystic lesions around the vagina and female urethra; some of the imaging differential considerations would include:
Gartner duct cyst: at or above the level of the pubic symphysis anterior to the vaginal wall
Bartholin gland cyst: posterolateral to distal v...
Cystic lesions of liver carry a broad differential diagnosis. These include:
simple hepatic cyst
adult polycystic liver disease
infectious: inflammatory conditions
pyogenic hepatic abscess
amoebic hepatic abscess
The differential for cystic lesions of the pancreas includes:
intraductal papillary mucinous neoplasms (IPMN)
serous cystadenoma uncommonly uni/macrolocular
pancreatic cysts occur in association with
von Hippel Lindau syndrome
autosomal dominant polycysti...
Testicular cystic lesions are a relatively common occurrence on testicular ultrasound. They result from widely variable pathological entities ranging from benign to malignant. These entities include:
simple testicular cyst
tunica albuginea cyst (mesothelial cyst)
cystic transformation of rete...
Cystic lung disease can occur in a number pathological conditions.
A lung cyst is an air filled structure with perceptible wall typically 1 mm in thickness but can be up to 4 mm. The diameter of a lung cyst is usually < 1 cm. By definition lung cyst can be distinguished from cavity...
The gamut for cystic lung disease is long, but includes:
pulmonary Langerhans cell histiocytosis
lymphoid interstitial pneumonia
cystic lung disease
The differential diagnosis of a cystic mass adjacent to the angle of mandible includes:
2nd branchial cleft cyst
lymphatic malformation (lymphangioma)
from metastatic squamous cell carcinoma
from metastatic papillary thyroid cancer
The differential diagnosis for cystic masses of the mediastinum include :
oesophageal duplication cyst
cystic degeneration of an intrathoracic tumour
mediastinal thoracic duct cyst...
The differential for cystic parotid lesions includes:
bilateral cystic parotid lesions
benign lymphoepithelial lesions of HIV
unilateral cystic parotid lesion(s)
first branchial cleft cyst: parotid lymphoepithelial cy...
Cystic pulmonary metastases are atypical morphological form on pulmonary metastases where lesions manifest as distinct cystic lesions. It is slightly different form the term cavitating pulmonary metastases in that the lesions are extremely thin walled.
It has been reported with many ...
A cystic retroperitoneal lesion can carry a relatively broad differenital which includes:
retroperitoneal cystic lymphangioma
retroperitoneal mucinous cystadenoma
retroperitoneal cystic teratoma
retroperitoenal cystic mesothelioma
pseudomyxoma retroperitonei with cystic change
A cystic spinal lesion can result from a number of disease entities. They include
Dandy walker malformation
certain skeletal dysplasias 2
tricho-rhino-phalangeal syndrome type I
due to a tumour
Deductive echocardiography is a step-by-step approach in diagnosing and differentiating congenital heart disease.
position of heart
Deep brain stimulation is used in a variety of clinical settings, predominantly in patients with poorly controlled movement disorders. Although effective, its exact mode of function continues to be poorly understood 2.
Careful patient selection and target selection are essential if the proced...
A generalised retardation in skeletal maturation has different causative or aetiological factors, these can be classified as follows:
chronic ill health
congenital heart disease (especially cyanotic)
chronic renal disease
inflammatory bowel disease
malnutrition: failure to thrive (FTT)
Delayed myocardial enhancement can occur in cardiac MR assessment due to a number of causes.
myocardial ischaemia: typically subendocardial and follows a vascular territory 1
nonischaemic dilated cardiomyopathy
Demyelinating disorders are a subgroup of white matter disorders characterized by the destruction or damage of normally myelinated structures. These disorders may be inflammatory, infective, ischaemic or toxic in origin and include 1-7:
multiple sclerosis (MS)
The differential diagnosis of dense metaphyseal bands is wide.
chronic anaemia, e.g. sickle cell disease, thalassemia
chemotherapy, e.g. methotrexate
growth acceleration lines following growth arrest due to systemic illness or stress in infancy or childhood, e....
Dental (periapical) abscess is an acute infection of the periapical tissue around the root of the tooth.
Patients may present with pain, oedema, and purulent discharge localised to the site of pathology with or without fever and tender cervical lymphadenopathy 1.
Dextrocardia is a congenital cardiac malrotation in which the heart is situated on the right side of the body (dextroversion) with the apex pointing to the right.
Dextrocardia is believed to occur in approximately 1 in 12,000 people 2.
There are two main types of dextr...
Diaphragmatic eventration refers to an abnormal contour of the diaphragmatic dome. It typically affects only a segment of the hemidiaphragm, compared to paralysis/weakness where the entire hemidiaphragm is typically affected.
Diaphragmatic eventration is congenital in nature and due...
Diaphragmatic paralysis can be unilateral or bilateral.
Clinical features are highly variable according to underlying aetiological factor
unilateral paralysis: asymptomatic in most of the patients as the other lung compensates.
may have dyspnea, headaches, fatigue, inso...
Diaphragmatic rupture often results from blunt abdominal trauma. The mechanism of injury is typically a motor-vehicle accident.
Given that the most common mechanism is motor vehicle collisions, it's perhaps unsurprising that young men are most frequently affected. Estimated incide...
Diaphyseal lesions are unsurprisingly predominantly found centred in the diaphysis.
simple bone cyst
myeloma / plasmacytoma
round cell tumour, e.g. Ewing sarcoma (children)
Most tumours of the CNS can potentially occur in the temporal lobe, but entities with a predilection for being diagnosed in this location include:
pleomorphic xanthoastrocytoma (PXA)
dysembryoplastic neuroepithelial tumour (DNET)
A small cardiothoracic ratio (CTR) as defined as <42%/0.42 when assessed on a PA chest radiograph, and can be due to number of entities:
adrenal insufficiency, e.g. Addison disease
asthmatic paroxysm ...
Uterine bleeding during pregnancy is a common clinical presentation that often necessitates obstetric ultrasound for the assessment of the haemorrhage, and of fetal well being.
The potential causes vary with the stage of gestation.
Bleeding in the first trimester
Differential diagnosis for calcified masses in the mandible includes:
calcifying odontogenic cyst (Gorlin cyst)
calcifying epithelial odontogenic tumour (Pindborg tumour)
Forefoot pain in the metatarsal region is a common complaint and may be caused by a number of conditions. It is worthwhile for a radiologist to have some knowledge of the potential causes and their imaging features.1
plantar plate disruption
The cul-de-sac, also known as the pouch of Douglas or rectouterine pouch, is an extension of the postero-inferior reflection of the peritoneal fold between the uterus (anteriorly) and rectum (posteriorly). It is the most inferior aspect of the peritoneal cavity and therefore the first location w...
The differential diagnosis of vascular calcification is very wide with many common and uncommon conditions.
end-stage renal failure 3
hemangioma; arteriovenous malformation
hyperparathyroidism, primary or secondary (renal osteodystrop...
An anterosuperior mediastinal mass can be caused by neoplastic and non-neoplastic pathology. As their name suggests, they are confined to the anterior mediastinum, that portion of the mediastinum anterior to the pericardium and below the level of the clavicles.
The differential diagnosis for a...
Diffuse alveolar haemorrhage (DAH) is a subset of diffuse pulmonary haemorrhage when bleeding is diffuse and directly into the alveolar spaces. It can occur in a vast number of clinical situations and can be life threatening.
Blood tends to fill alveolar spaces as multiple sites.
Diffuse bone sclerosis can result from a number of causes. They include:
sickle cell disease
diffuse osteosclerosing myeloma: rare
metabolic bone disorders