The lateral fossae are concave depressions of peritoneum in the paravesical space that lie between the lateral umbilical folds and the lateral parietal peritoneum. The lateral fossae are the smallest of the anterior paravesical fossae, and typically partially contain the cecum and/or sigmoid col...
The lateral umbilical folds are bilateral raised ridges of parietal peritoneum in the deep aspect of the anterior abdominal wall overlying the inferior epigastric vessels. The paired folds originate medial to the deep inguinal ring and end at the arcuate line on the posterior aspect of the anter...
The lateroconal fascia is the peritoneal thickening which extends anterolaterally from the adjoining merging lateral borders of the anterior and posterior perirenal fasciae.
It increases progressively in length as it ranges distally. It traverses laterally in a transverse plane a...
A handy mnemonic to recall the layers of the scrotum is:
Some Damn Englishman Called It The Testes
D: dartos fascia and muscle
E: external spermatic fascia
C: cremasteric fascia
I: internal spermatic fascia
T: tunica vaginalis
T: tunica albuginea
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, ...
Leiomyoma of the urinary bladder is a rare benign mesenchymal tumor of the bladder. The most common presenting complaints are urinary voiding symptoms such as obstruction and irritation.
These leiomyomas exhibit imaging characteristics on ultrasound, CT and MRI similar to those of uterine leio...
The lentiform fork sign has been described on MRI and is seen as bilateral symmetrical hyperintensities in the basal ganglia surrounded by a hyperintense rim delineating the lentiform nucleus.
It has been postulated to result from metabolic acidosis due to any cause 1, e.g. end stage renal dise...
Leptospirosis results from infection of the zoonoses Leptospira spp. The condition can have multiorgan manifestations. Commonly affected organs include:
lung: pulmonary leptospirosis
liver: hepatic leptospirosis
central nervous system: CNS leptospirosis
skeletal muscle: muscular leptospirosi...
Leukemia testicular manifestations, or testicular leukemia, can be seen in patients during and after acute leukemia. The blood-testis barrier limits chemotherapy from reaching the testicle, and therefore the testicle can act as a harbor for leukemic cells.
typically presents with painless testi...
Leukoplakia of the urinary tract is a squamous metaplasia of the urothelium (keratinization).
Clinically the condition presents with hematuria in one-third of cases, dysuria, frequency and nocturia, and thus it can mimic cystitis. Passage of the desquamated keratinized e...
The levator ani muscle, also known as the muscular pelvic diaphragm, is the musculotendinous sheet that forms the majority of the pelvic floor, supports the pelvic viscera, and aids in urinary and fecal evacuation as well as maintaining continence.
The levator ani has three main ...
A Leydig cell tumor of the testis is an uncommon testicular neoplasm. Its imaging appearance on ultrasound and MRI is nonspecific, but clinically it is associated with serum hormonal imbalance.
1-3% of all testicular tumors, but the most common sex-cord stromal tumor. Tend to be b...
Lichen planus refers to a dermatological condition that typically affects the skin, nails, oral cavity, genitals or perineum.
Skin lesions are characterized by violaceous scaly pruritic plaque eruption while oral lesions are characterized by erosions and lace-like reticular plaques. It is a chr...
Liddle's syndrome is an autosomal dominant condition which inhibits the normal degradation of the ENaC sodium channel, resulting in findings that mimic Conn's syndrome (hyperaldosteronism); hypernatremia, hypokalemia and elevated serum bicarbonate. Typically patients are asymptomatic other than ...
Lipomatosis is a condition where there is diffuse excessive fat deposition within the body. This can especially affect certain regions.
neck and upper region of trunk
lipomatous hypertrophy of the interatrial septum
lipomatous metaplasia of th...
Lithium-induced renal disease is characterized by a progressive decline in renal function, evidenced by increasing serum creatinine and decreased creatinine clearance. The lithium salt causes direct injury to the renal tubules. The duration of lithium therapy increases the risk of progression to...
Lobar nephronia, also known as acute focal nephritis, refers to an intermediate stage between acute pyelonephritis and renal abscess, and is a focal region of interstitial nephritis.
It appears as a wedge of poorly perfused renal parenchyma, without a cortical rim sign.
The condition is discu...
Lobster claw sign refers to a urographic pattern of papillary excavation that may be seen with renal papillary necrosis.
The lobster claw sign occurs when there is excavation around the edge of the papilla and the contrast material that extends into this excavated region looks like the "claws" ...
Localized cystic renal disease (LCRD), also known as localized cystic kidney disease, is an uncommon, non-familial, non-progressive disease characterized by clusters of cysts within the normal renal parenchyma. It can be confused with unilateral autosomal dominant polycystic kidney disease (ADPK...
Loin pain hematuria syndrome is a rare disorder in which patients suffer episodes of severe unilateral or bilateral flank pain with microscopic or gross hematuria in the absence of renal pathology.
Approximately 70% of patients are young females with a peak incidence in the third ...
A loopogram is a fluoroscopic study of an ileal conduit, which is a type of urinary diversion.
This procedure is also known is an ileal conduitogram, ileal loopography or ileostoureterography.
It is a retrograde study in which contrast is injected via the anterior abdo...
The loop-to-loop colon describes an abnormal colonic course associated with the absence of the left kidney from the renal fossa.
The transverse colon extends to the lateral margin of the abdominal wall and the descending colon courses medially to fill the renal fossa, resulting in a "looped" c...
Lower urinary tract symptoms (LUTS) are a constellation of symptoms including 1:
poor stream despite straining
hesitancy, frequency and incomplete emptying of the bladder
terminal dribbling (at the end of the urinary stream)
Although they are most frequently encountered in men with...
Lowe syndrome, also known as the oculocerebrorenal syndrome of Lowe, is a multisystem disorder characterized by anomalies primarily affecting the eyes, nervous system, and kidneys.
It is an extremely rare, pan-ethnic disease, with an estimated prevalence in the general population ...
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)
Lumbar hernias are a rare form of posterior abdominal hernia.
Most common in patients aged between 50 and 70 years with a male predominance 1.
Patients with lumbar hernias can present with a variety of symptoms, including a posterolateral mass, back pain,...
The lying down adrenal sign is a cross-sectional imaging sign of renal agenesis or ectopia in which the ipsilateral adrenal gland appears to be 'lying down' on the psoas muscle posteriorly. Due to the linear as opposed to Y-shaped configuration of the gland in such situations, it is also describ...
Lymphangioleiomyomatosis (LAM) is a rare multi-system disorder that can occur either sporadically or in association with the tuberous sclerosis complex (TSC) and is often considered a forme fruste of TSC.
It almost exclusively affects women of childbearing age 7. The estimated in...
Macronodular adrenal hyperplasia refers to a morphological type of adrenal hyperplasia in which there is adrenal enlargement in the form of large distinct nodules. It can be congenital or acquired.
A specific subtype under this entity is adrenocorticotropin independent macronodular adrenocortic...
A maiden waist deformity is a name given to the appearance when there is medial deviation of both ureters. This typically occurs in retroperitoneal fibrosis. In this condition, there is medial indrawing of the ureters due to deposition of fibrous tissue in the retroperitoneum at the level of the...
Mainzer-Saldino syndrome (also known as conorenal syndrome (CRS)) is a rare condition and is one of the ciliopathies. It is due to mutations in the IFT140 gene, whose protein product is one of the six parts of the intraflagellar transport complex A.
The syndrome's key characteristics are:
Malacoplakia of the urinary tract is an uncommon chronic granulomatous inflammatory disease of the bladder wall. Malakoplakia (meaning "soft plaque") can affect any organ, but the urinary bladder is the most common location.
Malacoplakia has a peak incidence in middle age and has ...
Male pseudohermaphroditism (MPH) is a variation of gender development.
Patients with male pseudohermaphroditism have 46 XY karyotype and may manifest as a female phenotype with various degrees of undervirilization secondary to partial androgen insensitivity.
The male reproductive system (or tract) includes:
It can be imaged using almost the entire range of imaging modalities but ultrasound and MRI are most often used (in part because...
The male urethra is a fibromuscular tube that drains urine from the bladder. It has a longer, more complicated, course than the female urethra and is also more prone to pathology.
The male urethra measures, on average, 18-20 cm in length. It commences at the internal urethral ori...
A helpful mnemonic to remember the 4 segments of the male urethra from proximal to distal.
Pet My Beautiful Pig
Posterior urethra equates to the prostatic and membranous urethras. Anterior urethra equates to the bulbous and penile ...
The Management of Incidental Adrenal Masses revised in 2017 by the Adrenal Subcommittee of the Incidental Findings Committee of the American College of Radiology is an algorithm for the management of patients who are:
adults (i.e. 18-year-old or over)
asymptomatic for adrenal pathology
The manta ray sign is a radiographic appearance in bladder exstrophy. It describes wide midline separation of the pubic bones simulating the appearance of a manta ray swimming towards you 1. The sacrum and iliac wings recall the manta ray’s head and body, with the widely spaced pubic rami formin...
A mature metastasizing teratoma is an uncommon complication of mature testicular teratomas, whereby distant metastatic deposits of histologically mature cells are encountered.
McCune-Albright syndrome (MAS) (also known as McCune-Albright-Sternberg syndrome) is a genetic disorder characterized by the association of:
endocrinopathy: precocious puberty
polyostotic fibrous dysplasia: more severe than in sporadic cases
cutaneous pigmentation: coast of Maine 'cafe au lai...
McDonald and McClellan classified crossed renal ectopia into four types 1:
bilateral crossed renal ectopia without fusion
unilateral crossed renal ectopia
bilaterally crossed renal ectopia: represents 90% of all crossed ectopias and includes crossed fused renal ectopia
crossed unfused rena...
The medial fossae are concave depressions of peritoneum in the paravesical space bounded by the medial umbilical folds and the lateral umbilical folds. The fossae are contained within the inguinal (Hesselbach’s) triangle. The right medial fossa typically partially contains the cecum and/or ileum...
The medial umbilical folds are bilateral raised ridges of parietal peritoneum in the deep aspect of the anterior abdominal wall formed by the underlying medial umbilical ligaments running from the pelvis to the umbilicus. The medial umbilical ligaments are anatomical remnants of the obliterated ...
The median umbilical fold is a raised ridge of parietal peritoneum in the deep aspect of the anterior abdominal wall overlying the median umbilical ligament representing the anatomical remnant of the foetal urachus. It is one of the 5 umbilical folds and should not be confused with the bilateral...
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.
Medullary cystic disease complex belongs to group of pediatric cystic renal diseases charaterised by progressive tubular atrophy with glomerulosclerosis (chronic tubulointerstitial nephritis) and multiple small medullary cysts.
There is no recognized gender predilection
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...
A common mnemonic used to remember the etiology of medullary nephrocalcinosis is:
A: (renal tubular) acidosis
M: medullary sponge kidney
P: papillary necrosis
renal papillary necrosis mnemonic
Medullary sponge kidney is a sporadic condition where the medullary and papillary portions of the collecting ducts are dysplastic and dilated and in most cases develop medullary nephrocalcinosis.
The incidence of medullary sponge kidney is estimated at ≈1:5000.
Megacystis megaureter syndrome describes the radiologic appearance of a large capacity thin-walled bladder and massive primary vesicoureteral reflux.
The pathophysiology of these massively dilated ureters and the large capacity bladder is the constant recycling of large volumes of r...
Melioidosis is an infectious disease caused by the bacterium Burkholderia pseudomallei (previously known as Pseudomonas pseudomallei) and is a multisystem disorder which may affect the lungs, brain, visceral organs, or musculoskeletal system.
Melioidosis is a disease of the monsoo...
Mesoblastic nephroma, also sometimes known as a congenital mesoblastic nephroma (CMN) or fetal renal hamartoma, is, in general, a benign renal tumor that typically occurs in utero or in infancy.
It is the commonest neonatal renal tumor. Diagnosis is usually made in the antenatal p...
Metallic ureteric stents are a type of ureteric stent developed to offer improved symptomatic relief of obstruction when compared to polymeric (polyurethane) stents. They are often used in patients with chronic malignant ureteric obstructions who require placement of long-term ureteral stents to...
Metanephric adenoma (MA) of the kidney is a type of benign renal neoplasm.
While it can present at any age 6, the peak age of occurrence is thought to be around the 5th to 6th decades 2. There may be a 2:1 female preponderance 2.
Metanephric adenoma is as...
Metanephric blastema (or metanephrogenic blastema) is one of the two embryological structure that gives rise to the kidney, the other one being the ureteric bud.
Persistent metanephric blastemas after 36 weeks of gestational age are called nephrogenic rests. They are associat...
Metaplasia is a general pathology term that refers to process when one cell type is replaced by another. It usually occurs in the context of a changed cellular environment to which the new cell type is better adapted 1. Examples include 2-5:
Barrett esophagus: normal squamous epithelium replace...
Metastases to testis are a very rare cause of a testicular mass and may be bilateral in up to 15% of patients.
Metastases to the testes are apparent in ~0.04% of autopsy studies in patients with known malignancy. The average age is 57 years, much older than the primary age for pr...
Microlithiasis (rare plural: microlithiases) merely means very small stones and may refer to:
The middle adrenal (suprarenal) artery is one of the three adrenal arteries that supply the adrenal gland.
The middle suprarenal arteries arise from the aorta on each side between the inferior phrenic artery and the renal artery. They run laterally across the diaphragmati...
Milk-alkali syndrome is the combination of:
It is due to a large amount of calcium and alkali being ingested (e.g. milk and antacids for peptic ulcer disease treatment or calcium carbonate for osteoporosis). It is a cause of medullary nephrocal...
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
Mixed gonadal dysgenesis (MGD) is a type of gonadal dysgenesis characterized by gonadal asymmetry, and/or sex chromosomal mosaicism, as well as retained Müllerian ducts.
Depending on the chromosomal composition, patients may have testes and/or streak gonads.
Mixed epithelial and stromal tumors (MEST) are a family of uncommon renal neoplasms in adults in a spectrum ranging from predominantly cystic (adult cystic nephroma) to more solid tumors.
There is a female preponderance 10:1 1 with tumors occurring predominantly in middle-aged pe...
The abdominal molar tooth sign refers to the appearance of contrast media which has spilled out of the urinary bladder on CT cystography after extraperitoneal bladder rupture.
Contrast flows out of the ruptured bladder, occupying the preperitoneal cavum Retzii and surrounds the bladder in the s...
The molar tooth sign may refer to:
molar tooth sign (CNS)
molar tooth sign (abdomen)
The mons pubis (plural: montes pubis) refers to the rounded protuberant skin-covered soft tissue overlying the symphysis pubis (in both sexes). It is most prominent in adult females.
In females it forms the most superior part of the vulva and it is also called the mons Veneris (plural: montes V...
Moth eaten calyx refers to the ragged, feathery calyceal outline due to irregular erosions of the calyx. It is one of the earliest excretory urographic appearance of genitourinary tuberculosis.
This appearance is due to necrotizing papillitis, which may further progress to form medu...
MR defecography is a dynamic study for evaluation of the pelvic floor and pelvic organ prolapse.
There are four phases of evaluation:
Method of evaluation
Many variations in the techniques described below exist.
MRI targeted prostate biopsy refers to an imaging targeted technique rather than the traditional systematic approach of a prostate biopsy after respective imaging with multiparametric MRI (mpMRI) of the prostate.
As a consequence of the recent advances of multiparametric MRI (mpMRI) of the pros...
MR spectroscopy is a promising development in the radiological evaluation of possible prostate malignancy.
The MR spectroscopic evaluation is mainly based on the choline peak elevation and choline-creatinine ratios.
Choline/creatine to citrate ratios:
> 0.5: suspicious
> 0.8: very suspiciou...
A mulberry stone is one of the types of urinary tract stones. It is formed of calcium oxalate dihydrate. It can be considered as a subset of a jackstone calculus which has a spiked appearance. When the stone has less well-developed spikes, it may appear to have a mamillated appearance, hence it ...
A Müllerian duct cyst is a cyst that arises from remnants of the Müllerian duct and is one of the midline cystic masses in the male pelvis.
Müllerian duct cysts usually occur in the 3rd and 4th decades of life (whereas prostatic utricle cysts are most often detected in the 1st an...
Multicystic dysplastic kidney (MCDK) is a type of non-heritable pediatric cystic renal disease. It results in multiple cysts being formed in utero in the affected kidney.
Unilateral incidence is estimated at 1:2500-4000. There may be a predisposition for the left kidney, a slightl...
Multicystic mesotheliomas are a rare benign subtype of mesothelioma.
The nomenclature for this condition can be confusing due to the use of multiple interchangeable different synonyms that put it together with the peritoneal inclusion cysts. Although there is still some debate on ...
Multilocular cystic renal neoplasm of low malignant potential is a low-grade adult renal tumor composed entirely of numerous cysts. The entity was previously known as multilocular cystic renal cell carcinoma, which usually had clear cell morphology, but was redefined in the 2016 WHO classificati...
Multiparametric MRI (mpMRI) of the prostate combines anatomic information from T1-weighted and T2-weighted sequences with functional information from diffusion-weighted imaging (DWI) and dynamic contrast enhancement (DCE). In some situations other techniques like MR spectroscopy (MRS) may also b...
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 endocrine neoplasia type II (MEN2) is also known as mucosal neuroma syndrome or multiple endocrine adenomatosis. It is a collection of syndromes characterized by the presence of multiple endocrine tumors.
They are autosomal dominant in inheritance, and share medullary thyroid carcinom...
Multiple endocrine neoplasia (MEN) type IIb, also known as MEN type 3 (MEN3) 3 or mucosal neuroma syndrome 2, accounts for only 5% cases of MEN2 and is characterized by:
pheochromocytoma(s): in 50% of patients, often bilateral, and can be extra-adrenal
medullary thyroid cancer: 100% of patient...
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)
Musculus compressor nuda is a small striated musculotendinous sling of the bulbocavernosus muscle, which extends from the anterior and lateral surfaces of the proximal bulbous urethra.
Musculus compressor nuda causes the proximal bulbous urethra to form a symmetric convex cone shape where the t...
N-acetylcysteine (NAC) if often used as a prophylaxis against contrast-induced nephropathy. Protocols for administration vary widely from institution to institution and the true efficacy is still controversial.
A typical protocol is [1-2]:
600 mg acetylcysteine twice daily on the day of the ex...
Neonatal hydronephrosis is most commonly diagnosed antenatally as fetal pylectasis, and in the majority of cases is due to pelvi-ureteric junction (PUJ) obstruction.
pelvi-ureteric junction (PUJ) obstruction (50% of cases 1,6)
vesicoureteric reflux (~20% of cases 5)
Nephroblastomatosis refers to diffuse or multifocal involvement of the kidneys with nephrogenic rests (persistent metanephric blastema).
Nephrogenic rests are found incidentally in 1% of infants.
Nephrogenic rests are foci of metanephric blastema that persist beyond 36...
Nephrocalcinosis, previous known as Anderson-Carr kidney or Albright 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%
Nephrogenic systemic fibrosis (NSF), also known as nephrogenic fibrosing dermopathy, is a complication of gadolinium-based contrast agents used in MRI.
It is characterized by "firm, erythematous, and indurated plaques of the skin associated with subcutaneous edema" 1. Eventually, flexure contra...
Nephroptosis, also known as floating/wandering kidney or ren mobilis, refers to the descent of the kidney more than 5 cm or two vertebral bodies when the patient moves from a supine to upright position during IVU 1,2.
Displacement can also occur medially across the midline, so-called medial nep...
Nephrostomy is a common urologic or interventional radiology procedure in which a tube/catheter is introduced into the renal collecting system (usually the renal pelvis).
Nephrostomies can either be
"open" nephrostomy: after a urological surgical procedure, such as a UPJ stone removal
Nephrotic syndrome results from loss of plasma proteins in the urine and characterized by hypoalbuminemia, hyperalbuminuria, hyperlipidemia, and edema. It may be caused by primary (idiopathic) renal disease or by a variety of secondary causes.
Patients present with marked...
Neuroblastomas are tumors of neuroblastic origin. Although they may occur anywhere along the sympathetic chain, the vast majority arise from the adrenal gland.
They represent the most common extracranial solid childhood malignancy and are the third commonest childhood tumor after leukemia and b...
There are two methods of neuroblastoma staging, one that is based on post-operative patients (INSS) and one developed for pre-treatment patients (INRGSS).
International Neuroblastoma Staging System (INSS)
This staging system is for post-operative patients and mainly for prognosis 1:
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...
Neurocristopathy syndromes encompasses a group of conditions united by abnormal migration, differentiation, division or survival of neural crest cells 1.
neurofibromatosis type I (NF1)