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64 Challenging Concepts in Urological Surgery
https://t.me/med1917
Learning point
Horseshoe kidney
● Horseshoe kidney incidence is 1
in 500 of the general population
but the stone incidence is
3,4
20– 30%.
● Aetiology:
– Failure of the kidneys to
ascend, possibly due to
failure of regression of caudal
blood supply (e.g. persistent
accessory iliac vessels).
– Lower poles fuse
together— isthmus.
– Inferior mesenteric artery—
landmark of isthmus.
● Horseshoe kidney is
disproportionately associated
with an increased incidence
of UPJO.
● Associated with Edwards,
Turner, and Down syndromes.
Evidence base National
Institute for Health and Care
Excellence 2019 guidelines
Diagnostic imaging: ‘offer urgent
(within 24 hours of presentation),
low- dose non- contrast CT to
adults with suspected renal colic.
If a woman is pregnant, offer
ultrasound instead of CT’.
Pain relief: ‘offer a non- steroidal
anti- inflammatory drug (NSAID) by
any route as first- line treatment for
adults, children and young people
with suspected renal colic’.
8
8
– Mechanical obstruction: presence of aberrant lower pole crossing vessels in up to 50% of cases;
does raise the possibility of a physical obstruction. This is supported by studies that show relief of
obstruction when the aberrant lower pole crossing vessels are mobilized and ‘hitched’— Hallström
technique or ligated.7 However, this area is still under debate.
Figure 6.1 Coronal view of a non- contrast CT scan of abdomen and pelvis. This shows right
peri- pelvicalyceal inflammation (arrow A) and multiple calculi in the right moiety (arrow B) of a
horseshoe kidney.
Expert comment Drainage of kidney
For patients with pyonephrosis (i.e. pus in the collecting system due to obstruction), then the old
surgical adage of ‘if there is pus about, let it out’ is as true today as it has ever been. Antibiotics do
not penetrate well into an infected collecting system and patients with pyonephrosis are going
to be profoundly septic and will need drainage. Many patients, however, even in the presence of
obstruction, do not develop pyonephrosis due to upper urinary tract infection and will resolve with
conservative measures.
This patient did not have clinical features of infected collection in that his temperature was not
swinging, it was not high- grade pyrexia, he was normotensive and only slightly tachycardiac, and,
therefore, a trial of fluid and antibiotics was entirely reasonable. If he had not settled, then drainage
would have been indicated and whether nephrostomy or stent would depend on local expertise.
The nephrostomy has a small risk of significant haemorrhage but guarantees drainage under local
anaesthetic whereas a stent involves anaesthesia for a potentially unstable patient and has a higher risk
of bacteraemia crisis.
Figure 6.2 Coronal view of a CT urogram. (a) Arterial phase showing an accessory artery entering the
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right lower moiety of horseshoe kidney arising from right common iliac artery (arrow A). (b) Excretoryphase CT urogram showing absence of contrast in the right ureter in keeping with right ureteropelvic
junction obstruction of the horseshoe kidney (arrow B). Contrast is seen in left ureter (arrow C).
The patient underwent a couple of radiological scans, and a technetium- 99m
mercaptoacetyltriglycine (MAG3) renogram showed 45% function of the right moiety
with an obstructed drainage pattern in keeping with UPJO. Unfortunately, following
the MAG3 renogram, he developed right loin pain that lasted a few hours but eventually subsided. The CT urogram (arterial phase and excretory phase) confirmed
multiple arterial blood vessels supplying the obstructed right moiety (Figure 6.2).
Thereafter, his case was discussed at the endourology multidisciplinary team meeting.
At the meeting, the stone burden was assessed, and all the calyces were identified
by three- dimensional reconstruction images. Potential management options were
explored.
65Case 6 Ureteropelvic junction obstruction
Evidence base Radiological tests used as a work- up for UPJO
Anatomical imaging
● Ultrasound scan of renal tract: determines hydronephrosis with assessment of renal parenchyma.
● Non- contrast CT scan of abdomen and pelvis: ureteric calculi.
● Contrast CT scan of abdomen and pelvis: delineates vascular anatomy (e.g. crossing vessels).
● CT urogram/ magnetic resonance urogram: level of obstruction.
Functional imaging
● MAG3 renogram: confirms obstruction and relative function. The radiolabelled isotope is injected
intravenously, 15 minutes following administration of furosemide (a diuretic). Four types of
renogram curves are described9:
– Type 1: normal uptake with prompt washout.
– Type 2: a rising uptake curve with no response to diuretics, which suggests obstruction.
– Type 3a: an initially rising curve that falls rapidly in response to diuretics, which suggests non-
obstructive dilatation.
– Type 3b: an initially rising curve that neither falls promptly nor continues to rise (equivocal).
● Whitaker test: largely, a historical test but has a role in equivocal cases of obstruction. This is an
invasive, dynamic test that measures the pressure gradient between the renal pelvis and bladder. It
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requires a nephrostomy tube and urinary catheter connected to pressure transducers. The patient is
prone and diluted contrast media is infused in an antegrade manner at a rate of 10 mL/ min.
– Pressure gradient <15 cmH2O = non- obstructed.
– Pressure gradient between of 15– 22 cmH2O = equivocal.
– Pressure gradient >22 cmH2O = obstructed.
10
At 8 weeks post discharge, the patient was reviewed in the outpatient clinic. I explained the diagnosis of congenital right UPJO with bilateral, multiple renal calculi. We
discussed all the options available, particularly the rationale for surgery. We agreed to
deal with the stone burden in the left moiety once the right moiety had been treated.
He underwent an uncomplicated, dismembered right pyeloplasty plus pyelolithotomy
plus antegrade JJ stent insertion via a low, right subcostal incision. During the operation, the relevant vascular anatomy to the right moiety was identified and preserved,
and the abnormal ureteropelvic junction segment was excised. Using a flexible cystoscope for identification, all renal calculi were removed with a nitinol tipless stone
extractor. The Anderson– Hynes pyeloplasty was performed.11. The renal pelvis was
deliberately not reduced in size. The abdominal drain was removed on day 2, urethral
catheter on day 3, and the patient was discharged home on day 4. He underwent a
flexible cystoscopy and JJ stent removal at 6 weeks, followed by a MAG3 renogram at 3
and 12 months. The histopathological findings reported were subepithelial fibrosis and
mild disarray of the muscularis bundles. He is asymptomatic and has good drainage
from the right moiety. Currently, he prefers to be managed conservatively for the stone
burden in the left moiety.
Expert comment Why not manage conservatively?
In cases of asymptomatic UPJO, conservative management is feasible because the aim of surgery is to
protect renal function and to alleviate symptoms. If the UPJO is incidentally detected, this may indicate
a stable chronic pathological entity and intervention has risks of nephrectomy and anastomotic
stenosis.
Previous evidence would suggest that the progression of renal loss in UPJO treated conservatively and
observed by serial renography may occur in one in ten patients but is unlikely without symptoms.
Once a patient has had a symptomatic episode, it is generally accepted that these are likely to recur.
Therefore, indications for intervention include:
● Recurrent pain
● Previous septic episode/ pyonephrosis
● Progressive renal loss on renography/ morphological features suggesting risk of complication (gross
hydronephrosis or stones)
● Lifestyle in which complications are likely, such as young age or contact sports, then surgical
correction is mandated.
Interestingly, following his MAG3 renogram, the patient developed right loin pain that lasted a few
hours but eventually subsided. This is referred to as Dietl’s crisis and is classical of UPJO.
Expert comment Intervention options
Endopyelotomy is a potential treatment for UPJO; however, the success rates are widely variable and
are less reliable regarding long- term de- obstruction rates than pyeloplasty. There are morphological
factors that would suggest an unfavourable outcome from endopyelotomy such as degree of
hydronephrosis, presence of lower pole crossing vessels, and worse ipsilateral split renal function.13
12
In this case, not only are there renal stones which would require an a percutaneous nephrolithotomy
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but the surgical anatomy (i.e. the horseshoe kidney) would add additional complication to an
endopyelotomy. A pyeloplasty remains the gold standard for definitive de- obstruction of UPJO
regarding symptom relief and renographic function, and in this case will allow stone clearance during
the same procedure.
The options for performing a pyeloplasty in a horseshoe kidney would be open, laparoscopic, or
robotic assisted. The benefits of a laparoscopic/ robotic approach would be small incisions and less
respiratory compromise and fewer long- term wound complications. This has become accepted as
the standard approach; however, with a more complex renal anatomy, a higher degree of expertise to
access each of the calyces would be extremely challenging laparoscopically. Use of the DaVinci robot
with the articulating wrist would allow access to all calyces but would require intraoperative robotic
ultrasound to check for stone clearance; again, this would be extremely challenging.
Expert comment Why insert a ureteric stent?
The use of a ureteric stent is to ensure safe drainage of the renal pelvis of the urine across the
anastomosis while it heals. Anastomotic leaks are a risk of pyeloplasty (although possibly less in
robotic cases with the facilitated suturing), and diverting urine by a ureteric stent reduces these; if they
do occur they are usually managed by reinserting a urethral catheter. A nephrostomy also reduces
leakage but may not act as a scaffold for the healing anastomosis to remain patent. Pyeloplasty is
performed in the paediatric population without ureteric stents without long- term sequalae.14 In adults,
a randomized study has shown no adverse consequences in ureteric stent removal at 1 week over 4
weeks. It might be tempting, therefore, to remove stents early because of symptoms; however, animal
studies have revealed that it can take a week for the mucosa to heal following ureteric disruption and
up to 4 weeks for the muscularis layer to be histologically healed. Hence the reason why ureteric
stents are traditionally kept in for 6 weeks. In the presence of stone disease, a stent is mandatory in
case of distal ureteric stone migration.
67Case 6 Ureteropelvic junction obstruction
Expert comment Why leave capacious right renal pelvis?
An aggressive reduction pyeloplasty is likely to give a faster return to a more normal- looking
excretion curve on a renogram and possibly reduce sluggish drainage in the long term. It does not,
however, improve pain or functional outcomes when compared with a more conservative reduction
in renal pelvis size; furthermore, post- pyeloplasty resolution of dilatation and hydronephrosis is
uncommon.15 In addition, the greater the reduction in tissue, the greater the operative difficulty.
More dissection is required leading to risk to renal blood supply; more suturing is required: the
greater the gap between pelvis and ureter (and hence difficulty in opposing the two), and the greater
chance of inadvertently closing a calyx. In the presence of stone disease, however, the possibility
of a large redundant pelvis having a sump- like effect to collect stone fragments and facilitate
possible future stone formation and the possibility that too large a pelvis may make future flexible
ureterorenoscopy technically more difficult.
A final word from the expert
This case highlights the complexity of unilateral UPJO in a relatively young patient with a
horseshoe kidney and bilateral renal stones. Therefore, I strongly recommend that this type of
case be discussed at the multidisciplinary team meeting. Thorough planning is vital to ensure
counselling of the patient with short- and long- term management objectives. Preoperative
planning, particularly with three- dimensional CT reconstruction images, will identify accessory
vessels such as those arising from iliac vessels, thus avoiding inadvertent injury. Furthermore, this
will aid in the identification of stones within calyces. Although minimally invasive (laparoscopic
68 Challenging Concepts in Urological Surgery
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and robot- assisted) pyeloplasty is increasingly the gold standard in adults,16 this is not the case
in horseshoe kidney with UPJO, as demonstrated with small case series reports.
17,18
In this case,
given the presence of a significant calyceal stone burden, open surgery was considered the best
approach for stone clearance and drainage. However, the future direction is likely to be robot
assisted given the increasing experience in robotic surgery, albeit in specialist centres.
Following pyeloplasty, if the drainage from the kidney is normal on renogram at 12 months,
patients may be discharged from further follow- up.19 In this case, postoperative repeat MAG3
renograms at 3 and 12 months showed good drainage. I would recommend long- term followup due to:
● Risk of recurrent urinary stone formation.
● Unresolved stone burden in left moiety.
● Risk of stone complications— pain, infections, and stone migration.
Although the patient is reluctant to receive further treatment, I would encourage treatment of
the stone burden in the left moiety.
References
1. Soucie JM, Thun MJ, Coates RJ, McClellan W, Austin H. Demographic and geographic vari-
ability of kidney stones in the United States. Kidney Int. 1994;46(3):893– 899.
2. Hiatt RA, Dales LG, Friedman GD, Hunkeler EM. Frequency of urolithiasis in a prepaid
medical care program. Am J Epidemiol. 1982;115(2):255– 265.
3. Janetschek G, Kunzel KH. Percutaneous nephrolithotomy in horseshoe kidneys. Applied
anatomy and clinical experience. Br J Urol. 1988;62(2):117– 122.
4. Cussenot O, Desgrandchamps F, Ollier P, Teillac P, Le Duc A. Anatomical bases of percutan-
eous surgery for calculi in horseshoe kidney. Surg Radiol Anat. 1992;14(3):209– 213.
5. Husmann DA, Milliner DS, Segura JW. Ureteropelvic junction obstruction with a simultan-
eous renal calculus: long- term followup. J Urol. 1995;153(5):1399– 1402.
6. Woodward M, Frank D. Postnatal management of antenatal hydronephrosis. BJU Int.
2002;89(2):149– 156.
7. Keeley FX Jr, Bagley DH, Kulp- Hugues D, Gomella LG. Laparoscopic division of crossing
vessels at the ureteropelvic junction. J Endourol. 1996;10(2):163– 168.
8. National Institute for Health and Care Excellence. Renal and ureteric stones: assessment and
management. NICE guideline [NG118]. National Institute for Health and Care Excellence.
2019. https:// www.nice.org.uk/ guidance/ ng118
9. O’Reilly PH, Lawson RS, Shields RA, Testa HJ. Idiopathic hydronephrosis— the diuresis
renogram: a new non- invasive method of assessing equivocal pelvioureteral junction obstruction. J Urol. 1979;121(2):153– 155.
10. Whitaker RH. Methods of assessing obstruction in dilated ureters. Br J Urol.
1973;45(1):15– 22.
11. Anderson JC, Hynes W. Retrocaval ureter; a case diagnosed pre- operatively and treated suc-
cessfully by a plastic operation. Br J Urol. 1949;21(3):209– 214.
12. Dietl J. Wandernde nieren and deren einklemmung. Wien Med Wohenschr.
1864;14(2):153– 161.
13. Samarasekera D, Chew BH. Endopyelotomy still has an important role in the management
of ureteropelvic junction obstruction. Can Urol Assoc J. 2011;5(2):134– 136.
14. Smith KE, Holmes N, Lieb JI, et al. Stented versus nonstented pediatric pyeloplasty: a
modern series and review of the literature. J Urol. 2002;168(3):1127– 1130.
15. Carpenter CP, Tolley E, Tourville E, Sharadin C, Giel DW, Gleason JM. Hydronephrosis after
pyeloplasty: ‘will it go away?’ Urology. 2018;121:158– 163.
16. Light A, Karthikeyan S, Maruthan S, Elhage O, Danuser H, Dasgupta P. Peri- operative out-
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comes and complications after laparoscopic vs robot- assisted dismembered pyeloplasty: a
systematic review and meta- analysis. BJU Int. 2018;122(2):181– 194.
17. Potretzke AM, Mohapatra A, Larson JA, Benway BM. Transmesenteric robot- assisted
pyeloplasty for ureteropelvic junction obstruction in horseshoe kidney. Int Braz J Urol.
2016;42(3):626– 627.
18. Spencer CD, Sairam K, Challacombe B, Murphy D, Dasgupta P. Robot- assisted laparoscopic
pyeloplasty for the management of pelvi- ureteric junction obstruction in horseshoe kidneys: initial experience. J Robot Surg. 2009;3(2):99– 102.
19. O’Reilly PH, Brooman PJ, Mak S, et al. The long- term results of Anderson- Hynes
pyeloplasty. BJU Int. 2001;87(4):287– 289.
69Case 6 Ureteropelvic junction obstruction
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7
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CASE
Oncocytoma
Andrew Deytrikh
Expert commentary Georgina Reall, James Lenton,
and Anthony Browning
Case history
A 30- year- old lady is referred by her general practitioner as a 2- week wait to the
urology outpatient department having presented with amenorrhoea. A subsequent
ultrasound scan (USS) of the abdomen and pelvis, arranged in primary care, demonstrated a large (59 × 59 × 53 mm) solid vascular mass arising from the left
kidney.
The patient was otherwise fit and well with no past medical history. There was
no family history of renal cancer and her performance status was 0. She was an exsmoker of 10 pack- years, drank approximately 40 units of alcohol per week, and took
the combined oral contraceptive pill.
Her renal function was within normal limits with an estimated glomerular filtration rate (eGFR) of 117 mL/ min/ 1.73 m2 and a creatinine level of 60 μmol/ L. Further
imaging in the form of computed tomography (CT) of the chest and abdomen with
renal phase was arranged. This revealed a 7.3 cm enhancing lesion arising from the
left kidney, with no involvement of the renal vein or associated lymphadenopathy.
Of note, a left- sided inferior vena cava (IVC) was described (Figure 7.1). These images were subsequently discussed in the urology cancer multidisciplinary team (MDT)
meeting, confirming a double IVC with dominant left side below the level of the renal
vein, and with a differential diagnosis which included oncocytoma or renal cell carcinoma (RCC). If the latter were to be true, then this lesion would be radiologically
staged as T2aN0M0.
Figure 7.1 CT abdomen and pelvis. (a) Axial and (b) coronal contrast- enhanced CT scans showing
a 7.3 cm relatively homogeneously enhancing central renal mass with a large central scar (arrow)
consistent with an oncocytoma. (c) Axial CT imaging showing an incidental left- sided IVC, not
associated with an oncocytoma but an important observation in order to prevent inadvertent damage
at the time of surgery.
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Learning point Incidence
The clinical condition and concept of oncocytomas was first described in 1942 by Zippel,1 and
subsequently the first case series was published in 1976.2 We now know that renal oncocytomas
represent between 3% and 7% of all renal tumours,
renal neoplasm. The incidence is higher in men than women with an up to three times male
preponderance,
oncocytomas are unilateral.3 They are formed of epithelial cells with an eosinophilic cytoplasm due
to their numerous mitochondria, the basic component of which is known as the ‘oncocyte’. It is
thought that renal oncocytomas originate from distal renal tubule epithelium, most likely intercalated
cells of the collecting duct.
Learning point Clinical presentation
Oncocytomas are not entities specific to the kidney. They have been described in a number of
organs, namely the salivary and thyroid glands, as well as the adrenals and kidney.3 The majority
of oncocytomas are asymptomatic at presentation and are identified incidentally, more so now
and going forward given the use of cross- sectional imaging, but a minority (17– 21%) do present
with symptoms (haematuria, flank pain, abdominal mass).
occur in a sporadic form without any underlying disease, or may occur in association with
other conditions including chronic renal failure, long- term haemodialysis, and Birt– Hogg– Dubé
syndrome.
Expert comment Left IVC
The fact that the patient has a dominant left IVC is not in itself a cause for concern, and the
operative approach, even with a left- sided renal tumour, does not require an overhaul. Prior to any
renal surgery, vascular variants should be noted, and appropriate and proportional consideration
given. The benefit of reviewing these images alongside a uroradiologist cannot be overstated, and
can prove invaluable. In this particular case, the left gonadal vein was found to drain directly into
the IVC, and was preserved at the time of surgery. A prior appreciation of the anatomy will mitigate
against any unpleasant surprises.
3– 5
with a peak incidence of between 40 and 60.6 Ninety- five per cent of
7,8
9
3,4
making them the commonest benign
3,4
Clinically, renal oncocytosis may
MDT discussion also explored the role of percutaneous biopsy of this renal lesion;
however, this line of investigation was not pursued as the patient preferred definitive
operative intervention rather than surveillance for her renal lesion. In this situation,
foregoing a percutaneous biopsy is entirely reasonable as it is unlikely to change the
upfront management. We will come on to discuss this point further.
The patient was counselled for a left laparoscopic radical nephrectomy, following
discussion and an opinion from the Royal Free Hospital, London. Her procedure was
uncomplicated; she was discharged on her first postoperative day and was given
dalteparin venous thromboembolism prophylaxis for 4 weeks. Histology was reviewed
and confirmed the presence of an oncocytoma (Figure 7.2) with clear resection margins and no evidence of malignancy.
Her creatinine level stabilized at 73 μmol/ L and her eGFR was 93 mL/ min/ 1.73 m2
at 2 years postoperatively. The plan going forward was to continue USS surveillance
of the right kidney for several years, the exact duration of which was not specified, to
ensure no contralateral recurrence.
73Case 7 Oncocytoma
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Figure 7.2 Histology slides. (a) A low- power view of a nested oncocytoma with hypocellular myxoid
stroma (×40, haematoxylin and eosin (H&E) stain). (b) A medium- power view showing uniformity of
tumour cells (×100, H&E stain). (c) A high- power view of oncocytes with uniform round nuclei and
granular eosinophilic cytoplasm (×400, H&E stain). (d) CK7 immunohistochemistry showing focal patchy
strong positivity typical in oncocytoma.
Learning point Histopathology
Macroscopically, the typical gross appearance of an oncocytoma is a solid, 5– 8 cm, wellcircumscribed lesion, often described as mahogany or tan in colour with a central pale scar (usually
seen in larger tumours). Microscopically, they have a nested architecture (other patterns, e.g.
tubulocystic and trabecular, are also seen) and the cells are described as oncocytic (polygonal with
copious granular eosinophilic cytoplasm, central small round nuclei). The background hypocellular
stroma is hyalinized or myxoid. Focal degenerative atypia resulting in bizarre nuclear morphology can
be present. ‘Invasion’ or extension into perinephric fat is sometimes seen; however, there should be no
necrosis and very few mitoses should be present.
Expert comment Histological and immunohistochemical features
On a well- sampled resection with typical histological and immunohistochemical features, it is
reasonable to confidently diagnose oncocytoma. On small core biopsies showing typical morphology,
increased confidence in the diagnosis may be gained from radiological and clinical input at MDT
meetings. In the absence of this supporting information, a cautious biopsy report of ‘oncocytic
neoplasm with features compatible with an oncocytoma’ might be recommended; if any histological
features fall outside of the typical range expected, good communication with the urologist is essential
in determining appropriate management for these patients.
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