4_primer_mankad_hoey_20150316195755 Flashcards
Renal Embryology
Kidneys form from pro-, meso- and metanephros; first two regress and only latter persistsUreteric bud from outgrowth of mesonephric ductForm in sacrum and migrate caudally by 8 weeks gestation; maturation continues to 5 y/o
US Medulla Cortex
Renal medulla hypoechoic to cortex
Renal Mass CT protocol
NoncontrastCorticomedullary phase (25-30 seconds)Nephrographic phase (80 seconds)
Location Septum of Bertin
90% upper pole, 60% bilateral Associated with bifid renal pelvis
Congenital megacalyces
Excess of enlarged calyces (20-25 vs normal 10-14), causing hypoplastic pyramidsNo obstruction, normal renal parenchyma and function
Pyelocalcyceal Diverticulum Types
Outpouching of calyx into corticomedullary region; usually asyptomatic but may cause calculiType 1: from minor calyxType 2: from infundibulumType 3: from renal pelvis
ADPKD
Cystic dilatation of collecting tubules and nephrons; 0.1% population, 10% dialysis patients, strong penetranceHepatic cysts (70%), intracranial berry aneurysms (20%), pancreatic and splenic cysts 60 y/o
Acquired cystic kidney disease
Multiple renal cysts developed in CRF; occur in 90% patients on dialysis3-5 cysts in each kidney, CRF and no history of inherited cystic diseaseHemorrhagic cysts occur in 50%, can ruptureRCC develops in 7%
Bosniak criteria
- Benign simple cyst, don’t communicate with collecting system2. Minimally complicated, benign but with concerning featuresThin septations (20) 2F. Multiple septa with or without perceptible but not measurable enhancement; can have thick or nodular calcification, also included if hyperattenuating and >3 cm3. Complicated, multiloculated but with malignant features. 4. Clearly malignant with large cystic component
Medullary cystic disease
Due to tubulointerstitial fibrosisPresents with anaemia and renal failureSmall kidneys with multiple small medullary cysts, often merely causes medullary increased echogenicity, thinned cortexThree typesFamilial nephronophthisis (70%): AR, juvenile onset at 3-5 years but also adult typeAdult medullary cystic disease (15%): AD inheritanceRenal retinal dysplasia (15%): recessive, associated with retinitis pigmentosa
Causes of Nephrocalcinosis
Metastatic (normal kidneys), dystrophic (injured tissue) or urine stasisHyperparathyroidism (primary and secondary)Metastatic carcinoma to bone and hypercalcaemia of malignancyProlonged immobilisationSarcoidosisMilk alkali syndromeHypervitaminosis DRTA (often dense medullary calcification)Medullary sponge kidney (urine stasis)HyperoxaluriaBartter’s syndromeProlonged frusemide (usually premature infants)Nephrotoxic drugsPapillary necrosis
Medullary sponge kidney
AKA Benign renal tubular ectasia, Cacchi-Ricci diseaseDysplastic cystic dilatation of papillary / medullary portions of collecting ducts, usually 20-40 y/o75% bilateral, often asymptomatic; 10% develop progressive renal failureIVP - striated nephrogram (brushlike), ‘bunch of flowers’ appearanceAssociations: Hemihypertrophy, Beckwith-Wiedemann, Pyloric stenosis, Ehlers Danlos, RTA, any form of renal cystic disease / ectopia,
RCC Types
Best evaluated in nephrographic phase, venous invasion best characterised by MRIUS: 70% hyperechoic if > 3 cm, 30% if
Oncocytoma
From epithelial cells of proximal tubule, usually well-differentiated and benign but need resectionCentral stellate scar (25-33% on CT) and spoke wheel (angiography), usually homogeneous enhancement, can’t differentiate from RCC on imaging, but FNA can discriminate
Staging RCC
I: kidney onlyII: extrarenal ± adrenal involvement, but confined within Gerota’s fasciaIII: A - renal vein, B - lymph node metastases, C - bothIV: A - direct extension to other organs through Gerota’s fascia; B - metastases (lung (55%) > liver > bone > adrenal > contralateral kidney (10%))
Renal lymphoma
Occurs in 8% lymphoma patients, 75% bilateral, NHL > HL.Characteristically, renal vessels remain patent despite encasementMR: hypointense to cortex on T1W, heterogeneously hypo to isointense on T2WPatterns (five):Mulitple renal masses (59%)Solitary mass (3%)Renal invasion (contiguous RP spread)Perirenal (10%)Diffuse renal infiltration (rare)
Renal metastases
Fifth most common metastatic site, mainly haematogenous spreadLung, breast and contralateral kidneyColonic metastases often solitary and exophyticMelanoma metastases often have perinephric extension
Angiomyolipoma
Benign hamartomas - blood vessels, smooth muscle, fat; DO NOT contain calcificationCan cause pain, haematuria, anaemiaUsually multiple in tuberous sclerosis (80% of TS have AML)Sporadic form commonest (80-90%): F/M = 4/1, usually middle aged; thus 4 cm often resected / ablated.Intratumoural fat almost diagnostic (CT or chemical shift), 5% do not contain fatMay extend into renal vein and IVC
Tuberous sclerosis
AD, variable penetrance; >50% sporadicEpilepsy, mental retardation and adenoma sebaceumAlso subependymal nodules, giant cell astrocytoma, peripheral tubers, retinal hamartomas, cardiac rhabdomyomas, lymphangioleiomyomatosis, shagreen patches, subungual fibromas, bone cysts50% have renal lesionsBilateral renal cystsMultiple AMLs are sine qua non of TS (15% patients)RCC (1-2%)
Renal adenoma
Solid lesion
Renal Pelvis Tumours
Tend to maintain reniform outline of kidneyInverted Papilloma (No malignant potential, 20% risk of associated urothelial malignancy)TCCSCC (5% renal pelvis tumours,
TCC of Upper Renal Tract
Often multifocal; 40-80% have bladder TCC but only 3% bladder TCC later develop upper renal tract TCC10% of upper renal tract neoplasms, 2-4% bilateral, 2-7% calcificationHyperechoic on US and hyperattenuating on CTCauses faceless kidney - obliteration of sinus fat and infiltration of parenchymaStippling sign on IVP - tracking of contrast interstitially in papillary lesionStricturing - thus can mimic renal TB60% ipsilateral recurrence and 50% have lung metastasesStage I and II: limited to lamina propria / muscular layer, III: renal parenchyma / adjacent fat, IV: metastatic (usually liver, lung, bones)
Indications for partial nephrectomy
Solitary RCC
Von Hippel Lindau
AD, almost 100% penetranceUsually renal cysts25-40% develop clear cell RCC (often 30-40 y/o), often synchronous / metachronous; often screen from 20’s.Also have pancreatic cysts (30%), islet cell tumours, phaeochromocytomas (10%, often multiple and ectopic, 50-80% bilateral), retinal angiomas, ANS haemangioblastomasMore rarely endolymphatic sac tumours, cystadenomas of epididymis, broad ligament cysts
GU Tuberculosis
Second most common site of TB, usually haematogenous spread, may be asymptomaticActive / healed pulmonary TB in 50%50% calcification (amorphous granular if active, dense punctate if healed tuberculomas - putty kidney)Usually bilateral asymmetrical involvement, 25% unilateralTubercles become cavities, communicating with calyces, which then stricture, can cause autonephrectomyCan cause epididymitis, hydrocoele, testicular mass, prostatitis, female infertility
GU Tuberculosis Imaging features
Kidneys - Smudged papillae, moth-eaten calyx, ‘hiked-up’ pelvis - cephalad retraction of infero-medial margin of pelvis at PUJUreters - Usually unilateral, beaded corkscrew appearance (alternating scarring & dilatation), aperistaltic and shortened (pipestem)Bladder - Chronic interstitial cystitis causing fibrosis; Small, trabeculated, VU reflux, wall rarely calcifiedProstate - Dense calcification
Emphysematous pyelonephritis
Usually diabetic & E Coli (gas forming gram negatives) infection, occasionally non-DM with obstructionBest diagnosed on CT, often requires nephrectomy if severeType 1 (pyelonephritis): Destruction > one third renal parenchyma, 70% mortality, gas in parenchymaType 2 (pyelitis): Destruction
Xanthogranulomatous pyelonephritis
Replacement of renal parenchyma by lipid laden macrophages, begins in pelvis and extends to cortex and medullaMultiple low attenuation (-10 to 30 HU) xanthomatous masses (may show fine calcifications, thin rim of peripheral enhancement) ± thickened Gerota’s fascia ± psoas abscessChronic indolent bacterial infection, usually E Coli or Proteus; 10% diabetic, typically middle aged females90% diffuse, 10% focalAbsent / decreased contrast excretion on affected side75% due to staghorn calculus; 25% due to PUJ obstruction or tumourMay lead to replacement lipomatosis (severe parenchymal atrophy)
Renal papillary necrosis and causes
Ischaemic coagulative necrosis of pyramids / medullary papillae; chronic tubulointerstitial nephropathy; predominantly affects medullaGradual development of cleft in papilla ± sloughing ± rimlike calcification’Lobster claw’ initially, then ‘ring sign’ around sequestered sloughed papilla, ultimately calyceal blunting after necrosis and absorptionCauses (due to ischaemic and/or infective necrosis)DMAnalgesiaSickle cellPyelonephritisRenal vein thrombosisTuberculosisObstructive uropathy
Renal Trauma Categories
80% blunt trauma, 20% penetratingAbsence of haematuria does not preclude serious renal injuryI (75-85%): Contusions, small lacerations with no communication with collecting system (includes isolated subcapsular and perinephric haematomas, conservative managementII (10%): Laceration through cortex ± urine extravasation; may be managed conservativelyIII (5%): Multiple deep lacerations with renal pedicle injuryIV (rare): PUJ avulsion / laceration of renal pelvis
Renal Haemorrhage
Suburothelial - thickened wall of pelvis / proximal ureter due to bloodSubcapsular - recent blood is higher attenuation than parenchyma, kidney flattened with elevated capsule, eventually may calcify; if large and chronic may cause hypertension (Page kidney)Perinephric - usually extends below renal margin
Renal infarction
Due to RA thrombosis or embolism, vasculitis, trauma, sickle cell, aortic dissectionRenal Artery Occulsion may present with Severe flank pain, haematuria, albuminuria, leukocytosis, fever, tender renal mass; or may be asymptomaticTypesGlobal: Non-enhancing kidney, high density capsular rim (collateral perfusion)Large branch occlusion: Wedge shaped defect, base on capsule, apex towards hilum, ± cortical rim enhancementSmall vessel occlusion (emboli, vasculitis, sickle cell): Multiple, often bilateral infarcts, ‘slit-like’ in sickle cell, may show cortical rim enhancement (unlike pyelonephritis)
Renal vein thrombosis
Causes smooth, swollen kidney with variable contrast excretion (can be dense nephrogram) ± occluded collecting systemCan cause cortical rim sign; varices may indent pelvis / ureterCT: prolonged corticomedullary differentiation, characteristic fine linear densities extending from kidney to perirenal space, enhance post contrastUS: Initially hypoechoic, then hyperechoic at 10 days due to cellular infiltrates / fibrosis; in late phase (several weeks) small hyperechoic kidney with loss of corticomedullary differentiationIf complete acute occlusion, can cause infarctionCauses:Malignant (extrinsic compression or direct extension)Primary renal disease (membranous GN commonest, SLE, amyloid)Secondary from IVC thrombosisInfants: sickle cell, haemoconcentration (diarrhoea, sepsis), hypoxia in congenital heart disease, maternal diabetes
Acute Cortical Necrosis Definition, Causes
Pathological progression of ATN; Ischaemic cortical necrosis with medullary sparing; usually bilateralAcute: unenhanced cortex between enhancing medulla and enhancing cortical rimChronic: small smooth kidneys, may show cortical calcificationCauses (60% ischaemia, 40% nephrotoxins): Haemorrhage (classically 3rd trimester)Septic abortionTrauma with shockSevere dehydrationHaemolytic uraemic syndromeAcute aortic dissectionTransfusion reactionToxins (including snake venom)
Renal artery stenosis
Causes: atherosclerosis (90%; narrows ostium or proximal 2 cm of RA), FMD (mid-distal RA, ‘string of beads’)Causes 1-5% HTN in young adultsCECT: Prolonged CMD implies significant stenosisCEMRA: Highly sensitive in proximal RASAngiography: Gold standard, but can’t assess haemodynamic significance of lesionUS: Peak systolic velocity > 150 cm/s, acceleration time > 0.07 s (parvus et tardus waveform), post-stenotic spectral broadening / flow reversal
Renal Transplant Complications
ATN (normal flow, reduced excretion) - rarely occurs > 1 month post transplantRejection (Resistive index >0.7 ([systolic-diastolic]/systolic, nonspecific), 90% show increased size (but normally decreased if chronic); thickened cortex; large renal pyramids with indistinct CM junction, focal hypechoic areas in cortex / medulla (20%), increased cortical echogenicity (15%)); hyperacute rejection shows decreased flow but delayed excretionCyclosporine toxicity - similar pattern to ATN but later post-transplant, rare within first monthArterial occlusion (87% success of angioplasty for anastomotic stenosis)Venous occlusion (RVT normally occurs in first 3 days post transplant)Urinary leakUrinary obstruction
Causes of perirenal fluid collections post-transplant
Lymphocoele (10-20% at 1-4 months post transplant; usually inferomedial to kidney and linear septations present in 80%)Abscess (usually develops within weeks)Urinoma (develops in first month, generally near VUJ, may be cold on nuclear medicine if not active)Haematoma
Ureteric development
From ureteric bud (if >1 bud, can have ureteric duplication), arising from mesonephric duct; 10-25 calyces/kidneyWeigert-Meyer: Upper moiety ureter inserts inferomedial to lower moietyThus upper moiety can develop ureterocoele (cobra head on IVP; can project into bladder and obstruct other ureter), lower moiety develops refluxUpper moiety may have extravesical insertion - typically bladder neck, urethra or vagina / seminal vesicles, vas deferensEctopic ureter F/M = 6/1; causes UTIs, obstruction, incontinence
Retrocaval ureter
Ureter passes behind IVC and exits between aorta and IVCMedial looping at L2/L3 on IVP, can cause ureteral narrowing
Ovarian vein syndrome
Right gonadal vein crosses ureter and drains into IVC, left gonadal vein drains to left renal veinUreteral notching / dilatation / obstruction due to ovarian vein thrombosis / varicesAssociated with pregnancy
Retroperitoneal fibrosis
Idiopathic form (two thirds) = Ormond’s Disease (M>F)Originates just inferolateral to aortic bifurcation and extends superiorly, but limited anteriorly by peritoneumTypically involves left ureter before right, usually at L3-L5 levelAssociations - IBD, PSC, fibrosing mediastinitis, Riedel’s thyroiditis, sclerosing mesenteritis, orbital pseudotumourImaging - Soft tissue layered around aorta and IVC, loss of peristalsis in involved ureteric segment (but always spares ureteric mucosa), does not extend between aorta and vertebrae (unlike malignant lymphadenopathy)Early or malignant RPF - high T2W; mature fibrotic plaque - low T2WRenal impairment out of proportion with degree of hydronephrosis, but stenting usually easy
Causes and Sequelae of RPF
Causes:AAARP metastases (lymphoma, breast, carcinoid) - Desmoplastic reaction: HD > NHL > anaplastic & metastasesRP haematomaRP abscess (diverticular, appendix)UrinomaDrugs (hydralazine, methylsergide, methyldopa, ergot)RadiationSequelae:Lower extremity / scrotal oedemaDVT
Retroperitoneal tumours
90 % malignant, usually > 10 cm at diagnosisMesodermalLiposarcoma (usually myxoid or pleomorphic; little fat on CT)Leiomyosarcoma (large heterogenously enhancing mass, central necrosis)FibrosarcomaLymphoma, othersNeuralNeurofibromaNeuroblastomaPhaeochromocytomaEmbryonicTeratomaPrimary germ cell tumour
Pelvic lipomatosis
True pelvis infiltrated by unencapsulated mature adipose tissueTwo thirds of cases are black malesCauses UTIs / obstruction, constipationAssociations: cystitis glandularis (75%, form of proliferative cystitis), increased risk bladder adenocarcinoma’Inverted pear’ shaped bladder, reduced bladder capacity, medial deviation of uretersEnlarged retrorectal space on Ba enema
Ureteritis cystica
Sterile submucosal fluid collections due to intramural inflammation, causing encystment and submucosal extension of transitional epithelium; not premalignantUsually unilateral, multicentric, smooth, round filling defects on IVU (most 2-4 mm diameter)Associated with chronic UTIs
Ureteral Psuedodiverticulosis
Outpouchings 1-2 mm of epithelium into lamina propria, associated with inflammation50% develop uroepithelial malignancy
Ureteric trauma
Usually penetrating injury causing urinoma / discontinuity / extravasationAvulsion usually at PUJ due to deceleration (commonest in children)
Malakoplakia
Yellow subepithelial plaques of mononuclear histiocytes containing Michaelis-Gutmann bodiesCobblestone appearance on IVP, most common in bladderF>M, usually diabetic or immunocompromised, strong association with E Coli UTIsCauses LUTs and haematuria; rarely invades bone
Ureteric tumours
50% develop bladder cancer, 75% unilateral, 5% bladder cancer patients develop ureteric cancerMalignant: Epithelial - TCC, SCC, adenocarcinoma; Mesodermal - Sarcoma, angiosarcoma, carcinosarcomaBenign:Epithelial - inverted papilloma, polyp, adenomaMesodermal - fibroma, haemoangioma, myoma, lymphangiomaGoblet sign: retrograde pyelogram with dilated ureteral segment distal to obstruction, with filling defect and mensicusMetastatic sites of ureteric primaries: RP LNs (75%) > liver, lung (60%) > bone (40%) > GIT (20%)
Bacterial cystitis
E Coli > Staph > Strep > PsuedomonasMucosal thickening (cobblestone), stranding perivesical fatEmphysematous cystitis usually E Coli in DM, neurogenic bladder (S2-S4 dermatome; UMN lesion = spastic, LMN lesion = atonic) or outlet obstruction (intramural gas, air/fluid level in bladder)
Cystitis cystica and glandularis
Cystica - mulitple serous fluid filled cystsGlandularis - mucin-secreting glandular hypertrophyChronic reactive inflammation, causes LUTs; muscle layer is intact; both can coexist with GU TBFilling defects on urography with hypervascular polypoid mass on CT & MRLow T1W, low signal with central branching high signal on T2W
Miscellaneous causes of cystitis
Radiation: approximately 15% of patients receiving pelvic irradiationCyclophosphamide: 40% develop haemorrhagic cystitisEosinophilic: Allergic reactions
Schistosomiasis
Association with bladder SCC, foreign body reaction in mucosa, M>F. DDx = TBBladder becomes fibrotic but remains distensible and normal volume.Inflammatory pseudopolyps = bilharzomasXR: Bladder wall (initally anterior at base, then encircles) and distal ureteric calcification (parallel / linear)IVU: Ureteritis cystica, ureteric dilatation / strictures
Inflammatory pseudotumour
Non-neoplastic proliferation of myofibroblastic spindle cells and inflammatory cells with myxoid componentsSymptoms: Haematuria, iron deficiency anaemia, feverSingle exophytic / polypoid bladder mass ± ulceration (but solid and cystic variants); spares trigone, can extend extravesicallyEnhances post contrast on CT and MR, can have internal flow on US
Endometriosis
Bladder commonest site of urinary tract involvement (1-5% of endometriosis, premenopausal only), cyclic haematuria in 20%Usually posterior wall above trigone or dome, may be inseparable from anterior wall of uterus, tends to be deeply infiltratingHigh signal T1W ± high signal T2W ± homogeneous or peripheral contrast enhancement
Nephrogenic adenoma
Benign reactive process to chronic irritation involving lamina propria but not muscle, not premalignant63% recurrence post resection
Bladder malignancy
4% of all cancers, M/F = 3/1, 50-60 y/oTCC (90%) - aniline dye, phenacetin, radiation, tobacco, interstitial nephritisSCC (5%) - calculi, chronic infection, schistosomiasisAdenocarcinoma (2%) - bladder exstrophy, urachal remnant, cystitis glandularis (10% pass mucus PU)95% carcinomas; leiomyosarcoma is commonest non-epithelial malignancyMetastases to bladder: stomach, breastUrachal carcinoma (0.4% bladder cancer, 40% bladder adenocarcinomas) - 70% calcified, 70% occur before 20 y/o
Staging bladder cancer
T1: Mucosa and submucosaT2: Superficial muscle layerT3a: Deep muscle layerT3b: perivesical fatT4: other organs
Leukoplakia
Squamous metaplasia of transitional epithelium (keratinisation), uncertain if premalignant; 30% have haematuriaAssociations: chronic infection (80%), calculi (40%)
Bladder trauma
Extraperitoneal rupture (Pelvic fractures) - conservative managementUsually occurs anterolateral at bladder baseCauses pear shaped bladderIntraperitoneal rupture (Blunt trauma, stab wounds) - surgical treatmentUsually occurs bladder domeContrast collects in paracolic gutters
Urethral injuries
Type 1: Intact urethra, stretched and narrowed by periurethral haematomaType 2: Rupture above urogenital diaphragm; extraperitoneal contrastType 3: Rupture below urogenital diaphragm; contrast in extraperitoneal space and perineum
Urethral strictures - causes
Gonococcal (commonest in USA, 40%) - usually bulbopenile urethraTB - ‘watering can’ perimeumCondylomata acuminata - HPV infection, papillary filling defectsTrauma - instrumentation, catheters (usually penoscrotal junction)Tumors (SCC 80%, TCC 15%; prostate cancer)
Female urethra, diverticulum and carcinoma
Female urethra ≤ 4 cm longDiverticula usually due to obstruction of Skene’s glandsCarcinoma - F/M = 5/1, 70% SCC, 90% in distal two thirds
Vas deferens course
Posterior aspect spermatic cord, diverges at deep inguinal ring, passing anterior to internal iliac artery, forming ejaculatory duct with seminal vesicle at prostatic base
Contents of Spermatic cord
vas deferens, vessels, lymphatics (drain to lateral and preaortic nodes) and nervesNeurovascular bundle in spermatic cord:Internal spermatic (tesicular - aorta), external spermatic (cremasteric - inferior epigastric) and differential arteries (to epididymis and vas - vesicular branch of internal iliac)Pampiniform plexus drains to ipsilateral testicular veinNerves: cremasteric nerve, genital branch of genitofemoral nerve and testicular sympathetic plexus
Testicular embryology
Genital ridges extend from T6 to S2Mesenchyme between seminferous tubules forms Leydig cells (begin to secrete testosterone at 8 weeks)Mesonephric ducts form epididymis, vas deferens, seminal vesicles and ejaculatory ducts, while paramesonephric ducts regressAt 7-8 weeks, testes descend to pelvis, staying at deep inguinal ring until seventh month, then descend to scrotum
Epididymitis
Commonest postpuertal acute scrotal pathology, likely ascending infection (gonococcal, E Coli, pseudomonas, TB); 20% develop orchitisAcute US: Swollen hyperaemic (only sign in 20%) hypoechoic epididymis (>5 mm thick)Thickened scrotal skin ± hydrocoele (if complex suggests pyocoele)Chronic US: Swollen epididymis ± hyperechoic