Chromaffin cells are neuroendocrine cells found predominantly in the medulla of the adrenal gland. They are also found in other ganglia of the sympathetic nervous system and are derived from the embryonic neural crest.
They arise in the fifth week of fetal development when neuroblas...
Chronic kidney disease (CKD), also known as chronic renal failure, is a progressive loss of glomerular function caused by a long-standing renal parenchymal disease. It is present when the glomerular filtration rate (GFR) is less than 60 ml/min/1.73 m2 for three consecutive months or greater than...
Chronic periaortitis is an inflammatory condition which typically involves the infrarenal portion of the abdominal aorta. It is a rare disease usually occuring in middle-aged men.
It has various clinical presentations:
idiopathic retroperitoneal fibrosis (IRF)
perianeurysmal retroperitoneal f...
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 prostatitis is a heterogeneous condition characterised by chronic inflammation of the prostate gland.
Under the National Institutes of Health (NIH) classification system this may encompass
chronic bacterial prostatitis
chronic prostatitis and chronic pelvic pain syndrome (CPPS)
Chronic pyelonephritis is form of pyelonephritis where there are longstanding sequelae of renal infection. At the time of writing there is still no definitive consensus at to whether the condition represents an active chronic infection, arises from multiple recurrent infections, or represents st...
Circumaortic left renal vein, also known as circumaortic renal collar is an anomaly of left renal vein when a supernumerary or accessory left renal vein passes posterior to the aorta, apart from the normal renal vein passing anterior to the aorta. This anomaly is potentially hazardous, if unreco...
A circumcaval ureter, or retrocaval ureter, is a developmental anomaly of the inferior vena cava (IVC). Unfortunately both terms suggest that the ureter is at fault, whereas in reality it is the IVC. They are of two types:
Many patients with this anom...
Citrate is a compound examined in MR spectroscopy in the setting of possible prostate carcinoma. Citrate resonates at 2.6 ppm and is decreased in prostate cancer.
For more information go to: MR spectroscopy in prostate cancer
The claw sign is useful in determining whether a mass arises from a solid structure or is located adjacent to it and distorts the outline.
It refers to the sharp angles on either side of the mass, which the surrounding normal parenchyma forms when the mass has arisen from the parenchyma. As suc...
Clear cell sarcomas (CCS) of the kidney are a rare mesenchymal renal tumour that accounts for ~5% of primary renal neoplasms in paediatric population 1.
CCS is the second most common primary malignant renal neoplasm after Wilms tumour, with an annual incidence of 20 cases in the ...
Cloacal exstrophy (CE) is an extensive congenital abdominal wall defect which encompasses:
exstrophy of the bladder
lower abdominal wall defect
The estimated prevalence is at around 1 in 50,000 to 200,000 live births. There is a recognised male predilection with a ...
The cloaca is the terminal portion of the hindgut. It is an embryonic structure (weeks 4-7) in which the distal ends of the gastrointestinal tract and urogenital system share a common channel. The most distal aspect of the cloaca is termed the cloacal membrane.
The cloaca, or portions of it, ca...
Cobb's collar(also known as a Moormann's ring) is an uncommon finding on a paediatric voiding/micturating cystourethrogram (VCUG), but an indentation of the bulbar urethra is seen in more than half of boy's who are cystoscoped, as the narrow represents two different phenomena3-4.
The cobra head sign (or spring onion sign) refers to dilatation of the distal ureter, surrounded by a thin lucent line, which is seen in patients with an adult-type ureterocoele. The cobra head appearance indicates an uncomplicated ureterocele.
The lucent "hood" of the cobra represents the comb...
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 ...
Colovesical fistulas are communications between the lumen of the colon and that of the bladder, either directly or via an intervening abscess cavity (foyer intermediaire). When the communication is between the rectum and urinary bladder, the term rectovesical fistula is used.
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 valv...
Congenital megacalyces is an incidental finding which mimics hydronephrosis. It is a result of underdevelopment of the renal medullary pyramids with resultant enlargement of the calyces. It it more frequently seen in males.
The enlarged, floppy calyces predispose to stasis, infection and calcu...
A congenital (primary) megaureter is a 'basket-term' to encompass causes of an enlarged ureter which are intrinsic to the ureter, rather than as a result of a more distal abnormality; e.g. bladder, urethra (see secondary megaureter). It encompasses:
obstructed primary megaureter
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 urachal anomalies are a spectrum of potential anomalies that can occur due to incomplete involution of the urachus.
A urachal remnant occurs in approximately 1 in 5000 patients.
The urachus connects the dome of the bladder to the umbilical cord during fetal ...
The conjoint tendon forms when the medial fibres of the internal oblique aponeurosis unite with the deeper fibres of the transversus abdominis aponeurosis. The conjoint tendon then turns inferiorly and attaches onto the pubic crest and pecten pubis 1. It forms part of the posterior wall of the i...
Conn syndrome (or primary hyperalderosteronism) is a condition of excess of aldosterone production and occurs secondary to adrenal cortical adenoma, bilateral adrenal hyperplasia, or rarely, adrenal carcinoma. Differentiation between the causes is required to avoid unnecessary surgery.
Contrast-enhanced ultrasound (CEUS) involves the administration of intravenous contrast agents containing microbubbles of perfluorocarbon or nitrogen gas. The bubbles greatly affect ultrasound backscatter and increase vascular contrast in a similar manner to intravenous contrast agents used in C...
Contrast-induced nephropathy (CIN) is the third most common cause of all hospital-acquired acute renal failure and accounts for ~10% of all cases. There is still an ongoing debate regarding its occurrence after intravenous contrast medium administration because most of the cases occur after intr...
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 common mnemonic for cortical nephrocalcinosis is:
C: cortical necrosis
A: Alport syndrome
G: (chronic) glomerulonephritis
medullary nephrocalcinosis mnemonic
The cortical rim sign is useful in distinguishing acute pyelonephritis from a segmental renal infarct and is seen on contrast enhanced CT or MRI.
The wedges of reduced enhancement seen in the setting of acute pyelonephritis represent oedema and ischaemia which involves the whole wedge of renal ...
Cowper duct syringocele refers to a cystic dilatation of the main duct of the bulbourethral (Cowper) glands.
Four groups of syringoceles have been described 2
minimally dilated duct
bulbous duct that drains into the urethr...
The cremasteric artery is a small branch of the inferior epigastric artery that enters the deep inguinal ring of the inguinal canal and supplies the layers of the spermatic cord and also the skin of the scrotum, including the cremaster muscle.
History and etymology
The word "cremaster" derives...
The cremaster muscle is the thin fascial muscle of the spermatic cord made of skeletal muscle. It is also referred to as cremaster fascia or simply the cremaster. Its action is to retract the testes, important in thermoregulation and spermatogenesis.
It is derived from the inter...
Crossed fused renal ectopia essentially refers to an anomaly where the kidneys are fused and located on the same side of the midline.
The estimated incidence is around 1 out of 1000 births 1. There is a recognised male predilection with a 2:1 male to female ratio. More than 90% of...
Crossed renal ectopia is said to be present when the kidney is seen in the opposite retroperitoneal space. It is more common for the left kidney to be ectopically located on the right side. More than 85% of these get fused resulting in crossed fused renal ectopia. Less than 15% cases are non-fus...
Cryptorchidism refers to an absence of a testis (or testes) in the scrotal sac. It may refer to an undescended testis, ectopic testis, or an atrophic or absent testis. Correct localisation of the testes is essential because surgical management varies on location.
The testes develop i...
CT abdomen is an increasingly common investigation that is used to help make diagnoses of a broad range of pathologies. A CT abdomen in its simplest form is a CT from diaphragm to symphysis performed 60 seconds after pump-injection of iodinated contrast intro a peripheral vein. However, dependin...
CT cystography is a variation of the traditional fluoroscopic cystogram. Instead of anterograde opacification of the urinary collecting system (as with CT urography), contrast is instilled retrograde into the patient's bladder, and then the pelvis is imaged with CT.
CT guided adrenal biopsy is usually performed for the diagnosis of indeterminate adrenal nodules or tumours. This procedure has declined in recent years due to improvements in, and validation of, non-invasive CT and MR techniques that can now diagnose benign adrenal lesions with a high degree of...
Computed tomography of kidneys, ureters and bladder (CT KUB) is a quick non-invasive technique for diagnosis of urolithiasis. It is usually considered the initial imaging modality for suspected urolithiasis in an emergency setting 1.
identification of calc...
CT polytrauma/multitrauma (also called trauma CT) is an increasingly used test in the patient with multiple injuries sustained after significant trauma.
There is some evidence that trauma patients who undergo whole body CT (WBCT) / panscan have better survival than patients who undergo selectiv...
CT urography (CTU or CT-IVU) has now largely replaced traditional IVU in imaging the genitourinary tract. It gives both anatomical and functional information, albeit with a relatively higher dose of radiation.
The aim is to illustrate the collecting systems, ureters and bladder with intravenous...
Cushing syndrome is due to the effects of excessive glucocorticoids which may be exogenous or endogenous.
In modern Western populations, iatrogenic steroid administration for treatment of inflammatory condition is the most common cause, e.g. asthma, rheumatoid arthritis.
A cyst is an abnormal fluid filled structure which is lined by epithelium. This distinguishes it from a pseudocyst with lacks an epithelial lining and instead has a vascular and fibrotic capsule
Cysts are extremely common and found in many organs. Examples include:
Cystadenocarcinoma of the rete testis is the malignant version of cystadenoma of the rete testis.
Primarily a disease of older men (>60 years old), but has been noted in a wide age range (8-91 years).
Histologic evaluation requires exclusion of malignant mesothelioma...
Cystadenoma of the rete testis is a rare cystic testicular tumour. It does not have specific imaging features, but may be suggested in the differential of a large multiloculated cystic tumor involving the testicle. It cannot be radiologically differentiated from cystadenocarcinoma.
Cystic adrenal neoplasms are uncommon and only account for a minority of cystic adrenal lesions 3. They may be represented several histological types:
adrenal adenoma 1
adrenal cortical carcinoma 1,2
adrenal epithelioid angiosarcoma 2
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...
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 renal disease can be confusing. There are many conditions, many of which have similar names or are eponymous, and with a few exceptions, are relatively rare. It is easiest to think of them into two separate demographic:
paediatric cystic renal diseases
adult cystic renal disease
Cystic renal dysplasia refers to a group congenital renal anomalies characterised by the formation of cysts. Many of the congenital cystic renal diseases fall under this group.
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
Cystinuria is an inherited condition in which there is an excess of cystine in the urine. This excess predisposes to the formation of cysteine stones.
"Cysteine" refers to the amino acid. "Cystine" is the oxidized dimer of the amino acid.
It is thought to occur in 1:...
Cystitis cystica is the same condition as ureteritis cystica and closely related to cystitis glandularis. It is a relatively common chronic reactive inflammatory disorders that occur in the setting of chronic irritation of the bladder mucosa.
Cystitis cystica is seen in a variety ...
Cystitis glandularis are small focal polypoid bladder mucosal thickenings and irregularities due to metaplasia of the urothelium (to mucin producing goblet cells) which proliferates into buds growing down into the lamina propria; this entity is closely related to cystitis cystica, with which it ...
Cystography is a fluoroscopic study that images the bladder. It is similar to a voiding cystourethrogram (VCUG), and the difference between the studies is primarily one of emphasis; a cystogram focuses on the bladder and a VCUG focuses on the posterior urethra. The study has been adapted to CT w...
Cystolithotomy is a urologic procedure to remove one or more bladder stones.
It is typically performed for a patient with large or numerous bladder stones or if an endoscopic approach has not been successful.
The traditional approach described below is an open cystolithotomy. Other approaches...
The dartos muscle is the thin rugated fascial muscle of the scrotum made of smooth muscle. Hence it is also referred to as dartos fascia or simply the dartos. It forms from the subcutaneous tissue of the scrotum and base of the penis and attaches to the scrotal skin and fibrous midline septum be...
The deep perineal pouch is an anatomic space above the perineal membrane in the urogenital triangle of the perineum, posterior to the transverse line between the ischial tuberosities.
The deep perineal pouch is above (deep to) the perineal membrane in the urogenital triangle.
A delayed nephrogram, commonly described on plain film urography, but also visible on CT urography, is when there is absence or reduction of the normal renal parenchymal enhancement on nephrographic phase images.
A delayed nephrogram is characteristically unilateral and is usually distinguished...
Developmental anomalies of the kidneys and ureters are numerous and not only potentially render image interpretation confusing but also, in many instances, make the kidneys more prone to pathology:
horseshoe kidney: most common
cross fused ...
Diabetes insipidus (DI) is the deficiency or resistance to the hormone vasopressin (antidiuretic hormone), which results in polyuria and polydipsia.
DI occurs in 3 per 100,000 people 2.
DI may be described as 1-3:
central/neurogenic/hypothalamic: vasopressin deficie...
The dialysis disequilibrium syndrome (DDS) is a situation characterised by development of neurological symptoms caused by rapid removal of urea during hemodialysis. It develops primarily from an osmotic gradient that develops between the brain and the plasma as a result of rapid haemodialysis. I...
Diverticula are out-pouchings of a hollow viscus and can be either true or false.
contains all layers of the wall of the parent organ (typically mucosa, muscular layer and serosa)
e.g. Meckel diverticulum
does not contain all layers (typically mu...
Dorsal nerve of penis or clitoris is one of the two terminal branches of the pudendal nerve that arises from nerve whilst in the pudendal canal. The other terminal branch is the perineal nerve.
Entering the urogenital triangle of the perineum, the dorsal nerve of penis o...
Double contrast cystography (pneumocystography) is an older technique to evaluate the bladder lumen. It has rarely been used (if ever) after the advent of cross-sectional imaging.
The exam is performed similarly to a conventional cystogram, but gas is also introduced through the Foley catheter....
Double retroaortic left renal vein is a very rare entity that is usually clinically silent and detected incidentally at imaging, surgery or autopsy.
The knowledge of anatomical variations helps the surgeon or interventionist to avoid complications during surgery and interventional procedures 4 ...
Drash syndrome, also known as the Denys-Drash syndrome, is associated with an abnormal WT1 gene (Wilms tumour gene) and consists of:
Dromedary humps are prominent focal bulges on the lateral border of the left kidney. They are normal variants of the renal contour, caused by the splenic impression onto the superolateral left kidney.
Dromedary humps are important because they may mimic a renal mass, and as such is considered a...
The drooping lily sign is a urographic sign in some patients with a duplicated collecting system. It refers to the inferolateral displacement of the opacified lower pole moiety due to an obstructed (and unopacified) upper pole moiety.
The similarity to a lily is further strengthened by the smal...
The ductus deferens (plural: ductus deferentes) forms part of the male internal genitalia where it transports sperm from the epididymis to the ejaculatory duct. In modern anatomic nomenclature, it is no longer referred to as the vas deferens.
The ductus deferens is a paired 30-45...
Calcification of the ductus deferens can result from:
diabetes mellitus - most common
chronic infection - more frequently irregular and unilateral
chronic urinary tract infection
A duplex collecting system, or duplicated collecting system, is one of the most common congenital renal tract abnormalities. It is characterised by an incomplete fusion of upper and lower pole moieties resulting in a variety of complete or incomplete duplications of the collecting system. While ...
Dynamic contrast enhancement (DCE) MRI is emerging as a useful clinical technique as part of a multi-parametric approach for evaluating the extent of primary and recurrent prostate cancer.
Protocol and equipment
Typically 3D T1-weighted fast spoiled gradient-echo MRI sequences with an endorec...
Echogenic renal pyramids in children can be due to many different causes.
Iatrogenic (most common cause)
Ectopic kidney (or renal ectopia) is a developmental renal anomaly characterised by abnormal anatomical location of one or both of the kidneys.
They can occur in several forms:
cross fused renal ectopia
ectopic thoracic kidney
The estimated incidence of an ectopi...
Ectopic testes are a rare congenital anomaly, differing from undescended testis (cryptorchidism) in that ectopic testis is a congenitally abnormally located testis, that has descended from the abdominal cavity away from the normal path of descent while undescended testis are congenitally abnorma...
An ectopic ureter is a congenital renal anomaly that occurs as a result of abnormal caudal migration of the ureteral bud during its insertion to the urinary bladder. Normally the ureter drains via the internal ureteral orifice at the trigone of the urinary bladder.
In females, the most common ...
The ejaculatory ducts are paired structures of the male reproductive system and convey seminal fluid.
Each ejaculatory duct is formed by the union of the excretory duct of the seminal vesicle and the ampulla of the ductus deferens and is approximately 2 cm long. They course throu...
Ejaculatory duct cysts are rare type of prostatic cyst.
They occur due to obstruction of the ejaculatory ducts which in turn can either be congenital or secondary (e.g. inflammation).
They are usually intraprostatic when small but may extend cephalad when large.
A useful mnemonic to remember the ejaculatory pathway of sperm is:
S: seminiferous tubules
V: vas (ductus) deferens
E: ejaculatory duct
Emphysematous cystitis (EC) refers to gas forming infection of the bladder wall.
The condition is rare and usually confined to certain patient subgroups.
Risk factors include:
considered the commonest predisposing factor 6
may be present in ~50%...
Emphysematous epididymo-orchitis is a rarely reported entity with only a handful of case reports which still lacks a strong evidence for the existence of the disease. It is reported as a rare cause of acute scrotum encountered in poorly controlled diabetics. Pathology of this condition is unknow...
Emphysematous pyelitis is defined as isolated gas production inside the excretory system, secondary to acute bacterial infection. It is a relatively benign entity and needs accurate differentiation from emphysematous pyelonephritis, which is a much morbid condition. It has an excellent prognosis...
Emphysematous pyelonephritis refers to a morbid infection of kidneys, with characteristic gas formation within or around the kidneys. If not treated early, it may lead to fulminant sepsis and carries a high mortality.
The patient usually presents with flank pain, urinary...
Empyemas are purulent inflammatory collections within a body cavity. They are similar to abscesses, which arise within parenchymal tissue rather than occupying a pre-existing anatomical space.
Colloquially, the term empyema is used to refer to thoracic empyemas but there are variou...
Endometrial carcinoma staging allows appropriate treatment options to be considered and enables greater prognostic accuracy for endometrial carcinoma.
Staging can be based on the TNM or FIGO system.
MR imaging is the modality of choice for staging with CT having relatively low speci...
End-stage kidney disease (ESKD), also referred as end-stage renal failure, corresponds to the last stage of a chronic kidney disease (stage 5), when the kidneys function is no longer sufficient to sustain life (GFR <15) and kidney replacement therapy (dialysis or transplant) is required.
The term epidermoid cyst can refer to a:
epidermal inclusion cyst
intracranial epidermoid cyst
splenic epidermoid cyst
spinal epidermoid cyst
testicular epidermoid cyst
An epididymal abscess is an uncommon complication of epididymitis.
Causative organisms are the same that cause epididymitis:
Other rare aetiological agents
An epididymal appendix (or alternatively appendix of the epididymis or appendix epididymis) is a testicular appendage that is a developmental remnant of the mesonephric duct (Wolffian duct) which can be found in the head of the epididymis 1. In 78% of the cases, it is stalked and is thus easily ...
Epididymal calcification can be seen on ultrasound as hyperechoic foci with shadows within the epididymal head and usually implies chronic epididymitis. Other conditions to be considered in the differential are:
chronic epididymitis: e.g. bacterial, granulomatous (TB) or genital filariasis
Epididymal cysts are the most common of epididymal masses.
Epididymal cysts have been reported in ~30% (range 20-40%) of asymptomatic individuals 5.
They are usually of lymphatic origin 2. Cysts contain clear serous fluid, lymphocytes, spermatozoa and debris.