Perirenal lymphoceles are the most common cause of perinephric fluid collection. They can potentially occur in a post-transplant situation in up to 25% of cases.
Perirenal lymphocele is usually asymptomatic but they can be large enough to cause hydronephrosis or venous ob...
The perirenal space is the largest of the three divisions of the retroperitoneum and is the most easily identified. It contains the kidneys, renal vessels and proximal collecting systems, adrenal glands and an adequate amount of fat to allow identification on CT scanning.
The space is surrounde...
There are several periurethral cystic lesions. These include:
female genitourinary tract:
Gartner duct cyst
epidermal inclusion cyst of the vagina
Skene duct cyst
Bartholin gland cyst
endometrial cyst of perineal-vulval-vaginal region
male genitourinary trac...
Perlmann tumour of the kidney (also sometimes known as benign adenomatous multicystic kidney tumour) is often mistaken for a malignant neoplasm. Many now consider it synonymous with the more well-known multilocular cystic nephroma.
Persistent fetal lobulation is a normal variant seen occasionally in adult kidneys. It occurs when there is incomplete fusion of the developing renal lobules. Embryologically, the kidneys originate as distinct lobules that fuse as they develop and grow.
It is often seen on ultrasound, CT or MRI...
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-...
Peyronie disease is the most common cause of painful penile induration. Fibrous tissue plaques form within the tunica albuginea, causing painful deformity and shortening of the penis. Though clinical diagnosis is usually accurate, the role of imaging is to evaluate extension of plaques, whether ...
Phaeochromocytomas are an uncommon tumour of the adrenal gland, with characteristic clinical, and to a lesser degree, imaging features. The tumours are said to follow a 10% rule:
~10% are extra-adrenal
~10% are bilateral
~10% are malignant
~10% are found in children
~10% are familial
A phantom calyx is a solitary calyx which fails to opacify with contrast amidst an otherwise well-opacified pelvicalyceal system. It is due to an intrarenal process which has infiltrated and caused obliteration of the involved collecting system element.
It may be seen in:
tumour: especially tr...
Pie in the sky bladder refers to the appearance of a contrast-opacified floating bladder seen high in the pelvis due to the presence of a large pelvic haematoma. This sign should raise concern regarding the possibility of an underlying urethral injury.
A pine cone bladder or christmas tree bladder is a cystogram appearance in which the bladder is elongated and pointed with thickened trabeculated wall. It is typically seen in severe neurogenic bladder with increased sphincter tone (detrusor sphincter dyssynergia) due to suprasacral lesions (abo...
Polyarteritis nodosa (PAN) is a systemic inflammatory necrotising vasculitis that involves small to medium sized arteries (larger than arterioles).
Polyarteritis nodosa (PAN) is commoner in males and typically presents around the 5th to 7th decades. Twenty to thirty percent of p...
Polyorchidism (or supernumerary testes) refers to the presence of more than two testes and is a very rare congenital anomaly. The supernumerary testis can be usually located inside the scrotum (75% of the patients) or less commonly in the inguinal canal, the retroperitoneum, or the abdominal cav...
The posterior pararenal space is the smallest and most clinically insignificant portion of the retroperitoneum.
It is filled with fat, blood vessels and lymphatics, but contains no major organs.
posteriorly: bound by transversalis fascia
anteriorly: bound by posteri...
Posterior urethral valves (PUVs), also referred as congenital obstructing posterior urethral membranes (COPUM), are the most common congenital obstructive lesion of the urethra and a common cause of obstructive uropathy in infancy.
Posterior urethral valves are congenital and only...
Post-transplant lymphoproliferative disorder (PTLD), also referred as post-transplant lymphoproliferation disorder, represents a variety of conditions ranging from lymphoid hyperplasia to malignancy, included in the 2008 WHO classification of tumours of haematopoietic and lymphoid tissues. It ca...
The Potter sequence is a constellation of findings demonstrated postnatally as a consequence of severe, prolonged oligohydramnios in utero.
It consists of:
pulmonary hypoplasia: often severe and incompatible with life
growth restriction (IUGR)
abnormal facies (Potter f...
Priapism is a term for a penile erection that occurs longer than desired. It may occur for multiple reasons, and the role of imaging in priapism is to distinguish between ischaemic low-flow priapism (95%) and non-ischaemic high-flow priapism (5%). In most cases only the corpora cavernosa are aff...
Primary cutaneous melanoma is the most common subtype of malignant melanoma, a malignant neoplasm that arises from melanocytes. Melanocytes predominantly occur in the basal layer of the epidermis but do occur elsewhere in the body. Primary cutaneous melanoma is by far the most common type of pri...
Primary hyperoxaluria, also referred as primary oxalosis, is a congenital autosomal recessive disease related to a liver enzyme deficiency leading to massive cortical nephrocalcinosis and renal failure.
Please, refer on secondary oxalosis for a discussion on the acquired form of hyperoxaluria....
Primary pigmented nodular adrenal dysplasia (PPNAD) is a rare benign adrenal condition characterised by ACTH-independent autonomous hypersecretion of cortisol, leading to Cushing syndrome.
PPNAD is inherited as an autosomal dominant trait, which has yet to be confidently mapped. ...
Primary melanoma of the prostate is rare, and usually cannot be diagnosed on imaging alone. In many cases, it is believed that in fact the tumour represents prostatic involvement by melanoma of the urethra.
Primary malignant melanoma of the prostate represent both a tiny fraction ...
Primary urethral cancer, in most cases a urethral carcinoma, is a rare urological malignancy. It can be divided in female urethral cancer and male urethral cancer.
It has an incidence of 4.3 per million for males and 1.5 per million for females. It usually manifests in the fifth d...
Primary urethral cancer staging often uses the TNM system and is as follows:
Primary tumour staging (T)
Tx: primary tumour cannot be assessed
T0: no evidence of primary tumour
Tis: carcinoma in situ
Ta: non-invasive papillary, polypoid, or verrucous carcinoma
T1: invasion of s...
Melanoma of the urethra is a very rare tumour of the male urethra, and often presents as an invasive prostatic mass. As such it is usually referred to as primary prostatic malignant melanoma.
primary cutaneous melanoma
primary non-cutaneous melanoma
The prostate gland is part of the male reproductive system and is the largest male accessory gland. It typically weighs between 20-40 grams with an average size of 3 x 4 x 2 cm. The prostate is comprised of 70% glandular tissue and 30% fibromuscular or stromal tissue 1-3 and provides ~30% of the...
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 cancer staging can be thought of in terms of physical location or grading histologically. The TNM classification is used to determine spread, and the Gleason score is used to determine the histological type. Another staging system is the Jewett-Whitmore staging system.
This is a basic article for medical students and other non-radiologists
Prostate cancer, also called carcinoma of the prostate or prostate carcinoma, is the commonest malignant tumour in men. It is primarily a disease of old age and many men remain asymptomatic.
This is a s...
Prostatectomy is a common procedure to remove the prostate gland, most often for prostate adenocarcinoma, although occasionally performed for benign prostatic hyperplasia. When performed for tumor, it is only indicated for tumors that are confined to the prostate.
There are two main types of pr...
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%...
PI-RADS (Prostate Imaging Reporting and Data System) refers to a structured reporting scheme for evaluating the prostate for prostate cancer. It is designed to be used in a pre-therapy patient.
The original PI-RADS score was annotated, revised and published as the second version, PI-RADS v2 6, ...
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...
Prostatic sarcoma is an uncommon and heterogenous group of tumour arising from mesenchymal cells in and around the prostate.
In children the most common tumour type is a prostatic rhabdomyosarcoma, which accounts for approximately a third of all prostatic sarcomas 1.
In adults leiomyosarcoma...
Prostate specific antigen (PSA) is currently used as a tumour marker for prostate adenocarcinoma.
PSA is a 33 kilodalton glycoprotein produced in prostate epithelial cells. Its normal physiologic role is as a liquefying agent for seminal fluid; only a tiny amount leaks into the blood, therefore...
Prostate-specific membrane antigen (PSMA) (also known as glutamate carboxypeptidase II) is a type II transmembrane glycoprotein that has become an increasingly prominent imaging biomarker 1. PSMA has emerged as a useful target in PET imaging of prostate cancer, especially in the evaluation of sm...
Prostatic abscesses can be a rare complication of prostatitis.
It has become relatively uncommon in clinical practice due to antibiotic therapy in those with prostatitis. It tends to affect diabetic and immunosuppressed patients. Most patients tend to present in the 5th to 6th de...
Prostatic artery embolisation (PAE) is a minimally invasive procedure option utilised to treat the benign prostatic hyperplasia (BPH).
PAE has been used for controlling prostatic haemorrhage (such as those associated prostate cancer) since 1970. However, its use in the treatment o...
Prostatic calcification is a common finding in the prostate gland, especially after the age of 50. They may be solitary but usually occur in clusters 7.
They are rare in children, infrequent below 40, and common in those over 50. Their number and size increase with age 8.
Prostatic carcinoma ranks as the most common malignant tumour in men and the second most common cause of cancer-related deaths in men. Prostatic adenocarcinoma is by far the most common histological type and is the primary focus of this article.
It is primarily a disease of the el...
Prostatic cystadenoma or multilocular cystadenoma of prostate is a rare benign neoplasm arising in the prostate gland.
If lesions are considerably large they may also be termed giant multilocular cystadenomas of the prostate.
Lesions are histologically characterised by glands and cy...
Prostatic infarction refers to necrosis of the prostate gland tissue from a lack of blood supply.
Histology slices on biopsy specimens may show reactive atypia 3.
prostatic artery embolisation
presumed pelvic ischaemia after
cross-clamping of the aorta for coron...
Prostatic tuberculosis or tuberculous prostatitis is an uncommon extrapulmonary manifestation of Mycobacterium tuberculosis infection.
Primary tuberculosis of the prostate is rare. Genitourinary tuberculosis contributes to 5-10% of extrapulmonary cases of tuberculosis in developed...
Prostatic utricle refers to Mullerian duct remnant in males which often manifests as a sac having a slit like orifice at the apex of verumontanum. This projects upward and backward into the substance of the prostate gland.
prostatic utricle cyst
Prostatic utricle cyst (PUC) is an area of focal dilatation that occurs within the prostatic utricle.
They are midline cystic masses in the male pelvis and can be very difficult or impossible to distinguish from a Mullerian duct cyst.
Utricle cysts are most often detected in the ...
The prostatic venous plexus is a network of veins around the anterolateral aspect of the prostate and anterior to the bladder. Tributaries include:
deep dorsal vein of the penis
anterior vesical rami
The receipt of blood from the vesical and prostatic rami connect the prostati...
Prostatitis refers to an infection or inflammation of the prostate gland that presents as several syndromes with varying clinical features. Prostatitis is a clinical diagnosis and imaging is useful to evaluate abscess formation.
The National Institutes of Health (NIH) have classifie...
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...
Prune belly syndrome, also known as Eagle Barrett syndrome 3 or triad syndrome, is a rare anomaly comprising a specific constellation of features. It consists of three major findings:
gross ureteric dilatation
anterior abdominal wall underdevelopment (resulting in the "prune belly" appearance)...
The PSA density (PSAD), is a calculation performed at diagnosis and is the serum PSA level divided by the volume of the prostate gland.
PSA density has been used as a prognostication tool in helping decide between a watch-and-wait or an invasive approach when managing prostate carcinoma. The c...
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...
Pseudoenhancement is an artifact in postcontrast CT evaluation of renal cysts.
The distinction between cystic and solid lesions visualised in CT is primarily made on the basis of whether the lesion enhances with contrast administration. A renal cystic lesion is considered "enhancing" when there...
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...
Pseudoureterocoeles are acquired dilatations of the submucosal portion of the distal ureter that mimic simple ureteroceles. The appearance of the radiolucent wall surrounding the dilated distal ureteral segment (cobra head sign) is an important differentiating point.
The distinction is importa...
A psoas hitch is a method of ureteric re-implantation following distal ureteric resection or injury.
The reconstruction is indicated when the distal ureter is injured or resected for cancer or stricture disease, and the remaining portion of ureter cannot reach the bladder for a ureteroneocystot...
Pulmonary-renal syndromes refer to a group of conditions that can affect the lung and kidneys. These conditions are typically characterised by diffuse alveolar haemorrhage and glomerulonephritis.
Diseases that can result in a pulmonary-renal syndrome includes:
certain pulmonary vasculitides
A putty kidney refers to a pattern of renal calcification associated with renal tuberculosis conventionally described on plain radiography. Calcification characteristically is very homogeneous and ground glass-like, representing calcified caseous tissue 3,4. Premkumar et al. labelled calcificati...
Pyelography (or "pyelogram") refers to imaging of the urinary collecting system.
The term is most often encountered in 'intravenous pyelography' (or "IVP"). For some, this is a misnomer and a test that images intravenous contrast as it travels through the kidney parenchyma into the urinary coll...
Pyelonephritis 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.
Pyelostomy is a rarely performed procedure in which a externalized catheter drains the renal pelvis. It is different from a nephrostomy in that the catheter enters the renal pelvis directly without passing though the renal parenchyma. It is much more prone to complication than a nephrostomy.
Pyonephrosis is a term given to an infection of the kidney with pus in the upper collecting system which can progress to obstruction.
The diagnosis of pyonephrosis is suspected when the clinical symptoms of fever and flank pain are combined with the radiologic evidence of urinary tract obstruct...
Both radiation and chemotherapy can result in severe haemorrhagic cystitis, the appearances of which vary with time from the therapy. It can be divided into acute and chronic.
In the acute phase of radiation and chemotherapy cystitis, there is a hemorrhagic cystitis secondary to denudat...
Randall's plaques are described as subepithelial calcification of the renal papilla 1 which are <2 mm in their greatest dimension. They act as an anchor for calcium oxalate crystals and are considered to be predisposing factor for renal stone formation.
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...
The rectouterine pouch, also known as the rectovaginal pouch, cul-de-sac or pouch of Douglas, is an extension of peritoneum between the posterior wall of uterus and the rectum in females. It is the most dependent part of the peritoneal cavity and is analogous to the rectovesical pouch in males.
Rectovesical pouch is the forward reflection of the peritoneum from the lower third of the rectum to the upper part of the bladder in males.
The rectovesical pouch is the lowest part of the peritoneal cavity and usually contains loops of small bowel or sigmoid colon. It is 7.5 cm...
Renal abscess, like any other abscess, is a collection of infective fluid in the kidney. It is usually a sequela of acute pyelonephritis, where severe vasospasm and inflammation may occasionally result in liquefactive necrosis and abscess formation.
It can affect all ages and has ...
A renal adenoma is type of benign renal neoplasm.
It is traditionally classified into three distinct types 1
renal papillary adenoma
renal tubular adenoma
alveolar renal adenoma
Renal agenesis refers to a congenital absence of one or both kidneys. If bilateral (traditionally known as the classic Potter syndrome) the condition is fatal, whereas if unilateral, patients can have a normal life expectancy.
Unilateral renal agenesis affects approximately 1 in ...
Renal amyloidosis is rare as an isolated entity but can be associated with systemic amyloidosis. Renal involvement from amyloidosis in pathological specimens is quite common. However, renal function compromise is rare.
It usually manifests as nephrotic syndrome:
Renal angiomyolipomas (AML) are a type of benign renal neoplasm encountered both sporadically and as part of a phakomatosis, most commonly tuberous sclerosis. They are considered one of a number of tumours with perivascular epitheloid cellular differentiation (PEComas) and are composed of vascul...
Renal antibiomas are postinflammatory cystic fluid
collections during or after antibiotic treatment for acute
pyelonephritis. These are usually < 3 cm sized, with no or minimal
post contrast wall enhancement or thickening.
They may mimic a renal abscess or perinephric abscess.
Renal arterial cut-off sign, as the name suggests, is an abrupt termination of the contrast-opacified lumen of the renal artery. It may or may not be associated with contrast extravasation.
It is seen in a vascular injury, e.g. segmental or main renal artery thrombosis or occlusion.
The renal arterial resistive index (RI) is a sonographic index to assess for renal arterial disease.
It is measured as
RI = (peak systolic velocity - end diastolic velocity ) / peak systolic velocity
the normal value is ≈ 0.60
with 0.70 being around the upper limits of normal
Renal arteriovenous fistulae (AVFs) are anomalous direct communications between arteries and veins in the kidney, which may be confused with a renal arteriovenous malformation (AVM).
The incidence of renal AVF is variable, estimated at 0.3-19% in native kidneys and 6-8% in ren...
Renal arteriovenous malformations (renal AVMs) are an uncommon vascular anomaly, which may be confused with a renal arteriovenous fistula (renal AVF).
Like arteriovenous malformations elsewhere in the body, a renal AVM is formed by a connection between the arterial and venous structu...
The renal arteries originate from the abdominal aorta and enter the renal hila to supply the kidneys. Any variant in arterial supply is important to clinicians undertaking surgery or other interventional renal procedures.
They arise from the abdominal aorta at the L1-2 ...
Renal artery aneurysms (RAA) are considered the second most common visceral aneurysm (15-22%), most common being splenic artery aneurysm (60%). They are more common in females. Most of the lesions are saccular and tend to occur at the bifurcation of main renal artery.
RAAs occur i...
Renal artery dissection may occur as a result of the following processes 1:
aortic dissection extending to involve the renal artery
iatrogenic (e.g. catheterisation)
connective tissue disease (eg. Marfan syndrome)
Renal artery occlusion can happen acutely due to in-situ thrombus, embolism, or dissection. Unless immediately treated, it can lead to renal infarction 1.
The condition is more common in the elderly, however, it may be seen in a younger age group if they have risk factors (describ...
Renal artery pseudoaneurysms are uncommon vascular finding, with the majority occuring after a renal intervention.
A renal artery pseudoaneurysm differs from a renal artery true aneurysm (as might occur in fibromuscular dysplasia) in that it does not involve all three layers of the a...
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 cell carcinomas (RCC) are primary malignant adenocarcinomas derived from the renal tubular epithelium and are the most common malignant renal tumour. They usually occur in 50-70-year old patients and macroscopic haematuria occurs in 60% of the cases.
On imaging, they have a variety of ra...
Renal cell carcinoma staging using the TNM staging system for renal cell carcinoma. Older but still widely used system in some practices is the Robson staging system.
TNM staging (7th edition)
T1a: tumour confined to kidney, <4 cm
T1b: ltumour confined to kidney, >4 cm but <7 cm
Renal colic (also known as ureteric colic) refers to a pattern of abdominal pain most commonly caused by ureteric calculi. The pain (usually unilateral) is felt in the loin radiating down to the groin and is typically colicky (i.e. coming in waves) corresponding to peristalsis or spasm of the ur...
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 cortical necrosis occurs as a result of severe systemic illness in a variety of settings and can result in permanent renal impairment.
severe haemodynamic shock
traumatic blood loss
Renal cysts are a common finding in the kidneys. Findings common to all "simple" renal cysts are well-marginated, thin walls with no enhancement of the cyst. They can be diagnosed on ultrasound, CT, or MRI. A cystic lesion in the kidney that deviates from the typical "simple" cyst appearance sho...
Renal dysgenesis is a very broad term which can include any form underdevelopment of the kidneys. The spectrum includes:
renal agenesis: complete lack of formation
renal hypoplasia: partial lack of formation
Some authors also classify any form of renal maldevelopment affecting size, shape of ...
Renal forniceal or calyceal rupture is the radiographic finding of a perirenal urine leak as a result of ureteric obstruction.
The renal fornices are the thin pointed projections, arising from the lateral aspects of each minor calyx, and extending a short distance into the renal column...
Renal haemosiderosis results from accumulation of haemosiderin in the kidneys. It is usually considered a benign and incidental radiologic finding and rarely results in clinically apparent renal dysfunction.
Renal haemosiderosis is a known complication of the following conditions:
A renal hilar lip is a developmental anomaly of the kidney. It is an infolding of the cortex at the level of the renal sinus and in this region the renal cortex appears thicker.
On imaging it appears as supra- or infra-hilar cortical bulges. At certain levels of cross-se...