Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1:
a central core consisting of necrotic inflammatory cells and local tissue
peripheral halo of viable neutrophils
surrounded by a 'capsule' with dilated blood vessel...
Adrenal calcification is not a rare finding in healthy asymptomatic people and is usually the result of previous hemorrhage or tuberculosis. Addison disease patients only occasionally develop calcification.
sepsis: Waterhouse-Friderichsen syndrome
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.
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 hemorrhage can result from a variety of traumatic and non-traumatic causes. When unilateral, it is often clinically silent. In contrast, bilateral adrenal hemorrhage can lead to catastrophic adrenal insufficiency.
The large majority of patients with unilateral adr...
Adrenal lesions cover a broad spectrum from benign to neoplastic entities. Due to increased use of cross-sectional imaging they are frequently detected as incidental lesions (incidentalomas). If found incidentally, please refer to the Management of Incidental Adrenal Masses: American College of ...
Tuberculous adrenalitis is the result of adrenal mycobacterium tuberculosis (TB) infection. Its incidence has decreased in the western world with the declining incidence of tuberculosis.
As the tuberculous infection causes destruction of the adrenal cortex, primary adrenal insufficie...
Asbestos related disease, in particular affecting the lung, comprise of a broad spectrum of entities related to the inhalational exposure to asbestos fibers. They can be divided into benign and malignant changes 1-3.
Benign pleural and parenchymal lung disease
asbestos related benign pleural d...
The differential for bilaterally enlarged adrenal glands is relatively limited:
micronodular adrenal hyperplasia
macronodular adrenal hyperplasia
adrenocorticotropin (ACTH)-independent macronodular adrenocortical hyperplasia (AIMAH) 2
Bilateral renal enlargement can arise from a number of causes which include 1:
diabetic nephropathy (common)
renal involvement with lymphoma
acute interstitial nephritis
vasculitis / autoimmune
autosomal recessive polycystic kidneys (ARPKD)
adult dominant polycys...
Bilateral testicular lesions have a relatively limited differential diagnosis.
lymphoblastic leukemia (acute or chronic)
primary testicular lymphoma is rare but the testes are often the site of lymphoma/leukemia recurrence due to ...
Bladder outlet obstruction can arise from a number of conditions affecting the urethra and/or bladder outlet.
Patients often present with difficulty in urination, retention and urinary discomfort 2.
Obstruction can be caused by multiple etiologies but is most...
Differential diagnosis for bladder wall thickening depends on whether the bladder is adequately distended. The bladder wall may be thickened if:
>3 mm when distended
>5 mm when nondistended
If the bladder is not distended, then it is difficult to exclude artifactual thickening from a collapse...
Brachytherapy, also known as sealed source radiotherapy or endocurietherapy, is a form of radiotherapy where a radioactive source is placed, under the guidance of imaging, within or next to the area requiring treatment.
Brachytherapy has been used to treat:
breast cancer (ofte...
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 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
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-recognized, especially asymptomatic variants 1.
The clinical ...
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 (...
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 categorized as following:
posterior urethral valve
anterior urethral valv...
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):...
Renal cortical nephrocalcinosis is ~20 times less common than medullary nephrocalcinosis.
renal cortical necrosis: common 2
toxemia of pregnancy
extracorporeal shock wave lithotripsy (ESWL)
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 retroperitoneal lesions can carry a relatively broad differential, which includes:
retroperitoneal mucinous cystadenoma
retroperitoneal cystic teratoma
retroperitoenal cystic mesothelioma
pseudomyxoma retroperitonei with cystic change
perianal mucinous c...
Echogenic renal pyramids in children can be due to many different causes.
Iatrogenic (most common cause)
Empyemas are purulent inflammatory collections within a body cavity. Contrast this with abscesses, which arise within parenchymal tissue, rather than occupying a pre-existing anatomical space.
Colloquially, the standalone term empyema is used to refer to thoracic empyemas but there...
The term epidermoid cyst can refer to a:
epidermal inclusion cyst
intracranial epidermoid cyst
splenic epidermoid cyst
spinal epidermoid cyst
testicular epidermoid cyst
Epididymal calcification can be seen on ultrasound as hyperechoic foci within the epididymal head. If the calcifications are large enough, then they may demonstrate acoustic shadowing.
chronic epididymitis: e.g. bacterial, granulomatous (TB) or genital filariasis
Epididymal masses are most commonly encountered on ultrasonography. Most epididymal masses are benign; malignant lesions are rare.
adenomatoid tumor of the scrotum (most common epididymal mass 4)
sperm granulomas / post vasectomy gran...
Extraprostatic (extracapsular) extension of prostate cancer refers to local tumor growth beyond the fibromuscular band surrounding the prostate gland. It is a pathological finding important to prostate cancer staging.
Though imperfect, MRI is superior to transrectal ultra...
The differential diagnosis for extratesticular cystic lesions includes:
loop of bowel from an inguinal hernia
Very rarely, a scrotal mesothelioma may present as a cystic mass.
Extratesticular scrotal masses (non-testicle and non-epididymis) are mostly mesenchymal in origin and benign 1.
lipoma (most common)
leiomyoma of the scrotum
granular cell tumor
fibrous hamartoma of infancy...
There are numerous fat-containing renal lesions, including:
renal cell carcinoma
renal or perirenal lipoma/liposarcoma
Non-mass lesions may also occasionally contain fat:
renal junction line
fat in a renal scar
renal sinus lipomatosis
Fetal pyelectasis refers to a prominence of the renal pelvis in utero that is a relatively common finding, which in the majority of cases resolves spontaneously.
Please refer to the article on fetal hydronephrosis for a continued discussion on this matter.
Although there is an ...
There numerous causes of gas in the bladder. In the hospital setting by far the most common is the recent placement of an indwelling urinary catheter. Other causes include 1:
indwelling urinary catheter is by far the most common cause
Hematospermia (less commonly hemospermia) refers to the presence of blood in semen or ejaculatory fluid. It is a symptom that can cause great anxiety in patients despite usually being of benign etiology.
urogenital infections including sexually transmitted disease, ...
Despite the vast majority of renal cancers being sporadic, there are a number of hereditary renal cancer syndromes:
von Hippel Lindau syndrome: predominantly clear cell type
tuberous sclerosis: predominantly clear cell type (also associated with angiomyolipoma)
Genitourinary manifestations of HIV/AIDS are protean and can be divided into:
renal diseases related to opportunistic infections: CMV, tuberculosis and MAC infections, fungal infections, pneumocystis carinii infection
drug-related renal diseases:
HIV-associated neoplasms are numerous and can be broadly divided into two groups:
associated but not AIDS defining malignancies
The development of these malignancies in HIV affected individuals generally implies progression to AIDS 4:
Hydronephrosis is defined as dilatation of the urinary collecting system of the kidney (the calyces, the infundibula, and the pelvis) 1.
Hydronephrosis in fetuses and newborns has specific causes that are covered in a separate article.
The term hydroureteronephrosis (or hydronephr...
Hyper-reninaemic hypertension may have many causes including:
renal artery stenosis
renal secreting tumor, e.g. renal cell carcinoma, reninoma
renal compression: large renal mass, subcapsular hemorrhage (Page kidney)
Increased renal echogencity is a nonspecific finding but can represent a number of underlying conditions.
chronic kidney disease: increased cortical echogenicity
sickle cell disease 4
echogenic renal pyramids - pediatric
Infertility is common, affecting 15-20% of couples, and is defined as the inability to conceive after one year of unprotected intercourse in the fertile phase of the menstrual cycle 3. It can be due to a variety of both female and male factors, and these are discussed in separate articles:
Intra-abdominal calcification in a neonate can be caused by a number of pathologies that cause calcification within the peritoneal space or within organs.
The commonest cause is meconium peritonitis which is the result of aseptic peritonitis secondary ...
Lead poisoning or plumbism is a multisystem condition due to the way in which lead interferes with the function of virtually every organ system. Plumbism most severely manifests due to its devastating effects on the CNS, but it also has important deleterious consequences on the skeletal, renal, ...
There are relatively few causes of low signal intensity renal parenchyma. Causes include:
paroxysmal nocturnal hemoglobinuria
mechanical: malfunctioning prosthetic cardiac valve
sickle cell disease
hemorrhagic fever with renal syndrome (HFRS)
Medical devices in the abdomen and pelvis are important to be recognized, just like medical devices of the chest. Often we ignore these devices, considering them to be incidental and non-pathological, however it is essential to be aware of potential complications.
Renal medullary nephrocalcinosis is the commonest form of nephrocalcinosis and refers to the deposition of calcium salts in the medulla of the kidney. Due to the concentrating effects of the loops of Henle, and the biochemical milieu of the medulla, compared to the cortex, it is 20 times more co...
The term milk of calcium (MOC) is given to dependent, sedimented calcification within a cystic structure or hollow organ. This sort of colloidal calcium suspension layering can occur in various regions:
renal: milk of calcium in renal cyst (most common)
breast: milk of calcium in breast cyst
Multiple endocrine neoplasia (MEN) syndromes are a collection of syndromes characterized by the presence of, as the name would suggest, multiple endocrine tumors. They are autosomal dominant in inheritance.
MEN1 (Wermer syndrome)
MEN2 (multiple endocrine adenomatosis)
MEN2a (Sipple syndrome)
Multiple filling defects within a ureter, as seen on conventional IVU or CT IVU, have a relatively small differential including:
spreading or multifocal transitional cell carcinoma (TCC)
multiple ureteral stones (steinstrasse)
Nephrocalcinosis, previous known as Anderson-Carr kidney or Albright's calcinosis, refers to the deposition of calcium salts in the parenchyma of the kidney. It is divided into several types, with differing etiologies, based on the distribution:
medullary nephrocalcinosis: 95%
Both neuroblastoma and Wilms tumor occur in early childhood and typically present as large abdominal masses closely related to the kidneys. Distinguishing between the two is important, and a number of features are helpful.
calcification very common: 90%
encases vascular structur...
Non-seminomatous germ cell tumors (NSGCT) are one of the main groups of germ cell tumors (the other being seminoma). Although they are made up of distinct histological entities, in general, they have similar radiographic appearances. They can, however, be found widely in the body, with variable ...
An obstructive uropathy is a catch-all term encompassing any cause of complete or partial, congenital or acquired and permanent or intermittent obstruction to the urinary tract. Depending on the severity of obstruction and extent, it may result in permanent change in both the collecting system p...
Oxalosis results in supersaturation of calcium oxalate in the urine (hyperoxaluria), which in turn results in nephrolithiasis and cortical nephrocalcinosis.
This article focus on the secondary oxalosis, please refer to primary oxalosis for a specific discussion on this entity.
Pediatric renal tumors and masses are another group of diseases (just like cystic renal diseases in both the adult and child) that are bewildering in their number, nomenclature and overlapping findings.
Wilms tumor: common in older children 1-8 years old
Paratesticular lesions have a long list of differential diagnoses:
epididymal cyst (most common epididymal mass)
adenomatoid tumor (most common epididymal tumor)
scrotal tunica cysts
tunica vaginalis cyst
tunica albuginea cyst
A paratesticular mass may derive from a number of structures that surround the testicle within the scrotum; most commonly, they derive from the spermatic cord.
The masses can be categorized as benign (70%) or malignant (30%).
spermatic cord lipoma (most common par...
Pear-shaped (or teardrop-shaped) bladder is one whose normal round or ovoid shape has been extrinsically compressed to resemble a pear. The pear may be inverted or upright, depending on how the excess pelvic tissue compresses the bladder.
Causes of a pear-shaped bladder inc...
Perinephric fluid collections are commonly seen after renal transplantation. The appearance of a perinephric fluid collection is often nonspecific but may be partially differentiated by when the transplant occurred.
Early post-transplant period (<4 weeks)
PET-CT is a combination of cross-sectional anatomic information provided by CT and the metabolic information provided by positron emission tomography (PET).
PET is most commonly performed with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG). Fluorine-18 (F-18) is an unstable radioisotope and has a half-...
Transrectal ultrasound–guided biopsy is considered the standard approach for prostate biopsy and is most commonly performed on an outpatient with a positive screening for prostate cancer.
Nowadays, with the MRI capacity for depicting abnormal areas of the prostate, is possible to obtain target...
Prostate cystic disease encompasses a wide variety of pathologies that all result in cyst formation within the prostate.
Prostatic cysts are common, and ~5-8% men will develop one 4,7. However they are much more common in patients being investigated for infertility, with one study showing a 20%...
Prostate peripheral zone T2 hypointensity is a common finding in pelvic MRIs that needs to be differentiated. A prostate directed MRI is usually performed using a multi-parametric technique to differentiate prostate cancer from more benign changes. This includes T2 weighted images, dynamic contr...
Prostatomegaly is a term used to generally describe enlargement of the prostate gland from whatever cause. Usually the prostate is considered enlarged on imaging when it measures beyond 30 cc (30 grams) in size.
The term prostatomegaly is often used interchangeably with benign pro...
Pseudobladder refers to a pelvic cystic mass that simulates the urinary bladder.
The location of the lesion should allow differentiation from the bladder but if doubt exists and clinical necessity arises, a delayed phase CT or MRI with excreted contrast or IDC-administered retrograde contrast f...
Pseudohydronephrosis refers to normal anatomy or non-significant pathologies that may mimic hydronephrosis. There is usually fluid-density material within a dilated of a part of the urinary tract, but without other signs of obstruction such as retroperitoneal fat stranding, renal perfusion abnor...
Pyelonephritis (plural: pyelonephritides) refers to an upper urinary (renal) tract infection with associated renal pelvis, renal calyceal and renal parenchymal inflammation, and comprises a heterogeneous group of conditions.
RASopathies are a class of developmental disorders caused by germline mutations in genes that encode for components or regulators of the Ras/mitogen-activated protein kinase (MAPK) pathway.
As a group, RASopathies represent one of the most common malformation syndromes, with an in...
Radiological manifestations of recreational drug use are not infrequently seen as the use of recreational drugs is widespread.
Interestingly, recent reports have suggested a decreasing incidence of reported drug use in the general population over the past decade, but it remains th...
Renal artery dissection may occur as a result of the following processes 1:
aortic dissection extending to involve the renal artery
iatrogenic (e.g. catheterization)
connective tissue disease (eg. Marfan syndrome)
Renal artery stenosis (RAS) refers to a narrowing of a renal artery. When the process occurs slowly, it leads to secondary hypertension. Acute renal artery stenosis does not lead to hypersecretion of renin.
When the stenosis occurs slowly, collateral vessels form and supply the kidne...
Renal cortical defects have a variety of causes, and present on imaging as an area of focal cortical thinning or absence of renal cortex, sometimes accompanied by focal caliectasis.
The differential diagnosis for a renal cortical defect includes 1,2:
Renal papillary necrosis refers to ischemic necrosis of the renal papillae. Necrosis also occurs in the medullary pyramids.
Patients can present with both acute episodes or chronic renal papillary necrosis. Calyceal or ureteral obstruction by sloughed papillae manifest with f...
A renal pseudotumor is a mass that will simulate a tumor on imaging but is composed of non-neoplastic tissue. There are many examples 1:
prominent column of Bertin
persistent fetal lobulation
cross-fused renal ectopia
renal hilar lip
Renal transplantation is one, if not the most, common transplant procedures undertaken worldwide. Consequently, purposeful and incidental imaging of renal transplants and renal transplant-related complications are increasingly common. These include acute renal transplant rejection and chronic re...
Renal vein varices develop for various reasons and are usually asymptomatic.
Renal vein varices are usually asymptomatic. Some patients may present with flank pain and/or hematuria.
chronic renal vein thrombosis
Right iliac fossa mass is a common clinical presentation and has a range of differentials that need to be excluded. Radiology plays an important role in this differentiation.
Risk factors for testicular germ cell tumors (GCT) include:
Caucasians at higher risk than African Americans (9:1)
10-40x increased risk
around 10% of all tumors are associated with undescended testis
higher risk if intra-abdominal testis compared with intra-inguinal
Sciatic hernia is a rare type of pelvic floor hernia, which occurs through either the greater or lesser sciatic foramina. It can contain variable structures.
curlicue ureter sign
The scrotum and its content are subject to a number of infective processes including:
Scrotal tunica cysts are paratesticular cystic lesions. They include:
tunica vaginalis cysts
tunica albuginea cysts
Typically seen as a simple appearing paratesticular cystic lesion not in the region of the epididymis.
Solitary filling defect with a ureter, as seen on conventional IVU or CT IVU has some differentials, including:
within the lumen
within the wall
transitional cell carcinoma (TCC)
When multiple fi...
Testicular cancers are the most common neoplasm in men between the ages of 20 and 34 years.
Testicular cancer is uncommon, accounting for less than 1% of all internal organ malignancies 2.
The demographics of affected individuals depends on the age of the histology of the tumor. ...
Testicular microlithiasis (TM) is a relatively common condition that represents the deposition of multiple tiny calcifications throughout both testes.
The most common criterion for diagnosis is that of five microcalcifications in one testicle, although definitions have varied in the past. In t...
Testicular trauma is the third most-common cause of acute scrotal pain and may result in various degree of damage to the testes.
Testicular rupture and testicular ischemia/infarct are two severe complications which need to be ruled out. Other injuries that can occur include 1:
Tumors of the male urethra are uncommon. They can be categorized both on the grounds of histology and location.
squamous cell carcinoma of the urethra: 80%
urothelial/transitional cell carcinoma of the urethra: 15% (predominantly posterior urethra)
adenocarcinoma of the urethra: 5%...
The differential diagnosis for unilateral testicular lesions is wide-ranging.
seminoma (40-50% of testicular malignancies)
non-seminomatous germ cell tumors:
testicular epidermoid (teratoma with ectodermal elements only)
There are numerous causes of urinary bladder diverticula:
Primary (congenital or idiopathic)
Hutch diverticulum (in paraureteral region)
bladder outlet obstruction
bladder neck stenosis
posterior urethral valve
prostatic enlargement (hypertrophy; carcinoma)
A urinary bladder diverticulum (plural: diverticula) is an outpouching from the bladder wall, whereby mucosa herniates through the bladder wall. It may be solitary or multiple in nature and can vary considerably in size.
There are two peaks; one at 10 years and the other at 60-70 ...
Causes of urinary bladder wall or lumen calcification include:
schistosomiasis of the urinary tract
calculus in a urachal cyst or in a bladder divertic...
Urinary diversion is created after the removal of the urinary bladder (radical cystectomy or cystoprostatectomy, usually done to treat invasive bladder cancer).
There are three main varieties:
neobladder formed from a segment of ileum (i.e. ileal conduit, also known as a "Bricker conduit")