Immunohistochemistry in Ureteropelvic Junction Obstruction and Its Correlation to Postoperative Outcome

Association between intraoperative anatomical variation and histopathological parameters in cases of ureteropelvic junction obstruction in children: A cross-sectional study

Introduction

The intraoperative anatomical findings (IOAF) of all ureteropelvic junction obstruction (UPJO) cases are not identical. Moreover, there is also controversy in the literature regarding histopathological (HP) findings in cases of UPJO. In the present study, we evaluated different IOAF and assessed their association with specific HP parameters.

Materials and Methods

This was a cross-sectional study set-up, which was carried out in a tertiary care centre. Children with UPJO who underwent surgery between 2017 and 2020 were enrolled. The following IOAF were noted: Type of pelvis (extrarenal or intrarenal), insertion of the ureter (high or normal), presence of lower pole crossing vessel (CV), negotiation of UPJ segment with double J stent (3 Fr) and length of internal narrowing (LIN) at UPJ. The resected segment of UPJ was assessed at three levels (pelvis, UPJ and ureter) for various HP parameters including fibrosis, oedema, inflammation and smooth muscle hypertrophy (SMH).

Results

Thirty-nine children were included in the study with a mean age of 31 months. The summary statistics of IOAF were intrarenal pelvis in 5 cases, high insertion of the ureter (HIU) in 9, CV in 6, negotiable UPJ in 23, and 16 cases showed LIN >1 cm. All cases showed SMH at the pelvis region and SMH with fibrosis at the UPJ region. At the pelvis region, there was an association between (1) HIU with oedema and chronic inflammation (CIF), (2) CV with CIF and (3) LIN with CIF and SMH. At the UPJ region, there was an association between (1) CV and negotiable UPJ with less fibrosis and (2) LIN with SMH. At the ureteric end, CV showed an association with less fibrosis and more CIF.

Conclusion

All UPJO cases have some common HP findings. Although, some particular IOAF, i.e., presence of CV, negotiable UPJ, HIU and LIN showed association with specific HP parameters.

Variation in the Expression of Interstitial Cell of Cajal-like Cell (CD117) Across Congenital Pelvic-ureteric Junction Obstruction and its Renal Sonological and Functional Correlation: A Prospective Observational Study

Aims and Objectives

This study aims to study the variation in the expression of CD117-positive interstitial cells of Cajal-like cells (ICC-LC) across the upper urinary tract region in children presenting with pelvic-ureteric junction obstruction (PUJO) and its association with renal functional and sonological parameters of patients.

Materials and Methods

A prospective observational study was done on 20 children with congenital PUJO who underwent dismembered pyeloplasty. All children underwent renal sonography (anteroposterior pelvic diameter [APPD], pelvicalyceal ratio [P/C ratio], Mid polar renal parenchymal diameter [MPPD]) and functional imaging scan (LLEC scan or DTPA scan). Three specimens were taken intraoperatively from above PUJ, at the level of PUJ, and below PUJ. Those were examined immunohistochemically using CD117 to count ICC-LC using standard criteria. Variation in the expression of CD117-positive ICC-LC was correlated with the abovestated parameters.

Results

The number of CD117-positive ICC-LC showed a continuous decreasing trend above downward. P/C ratio and APPD showed a parallel trend with ICC-LC distribution, whereas split renal function (SRF) showed an inverse relationship with the expression of ICC-LC. Children with lesser severity of obstruction (APPD <30 mm and SRF >40%) showed a uniform decreasing trend in the number of CD117-positive ICC-LC across PUJ. Children with more severe obstruction (APPD >30 mm and SRF <40%) showed a decrease in the expression of ICC-LC up to the level of PUJO followed by a sudden relatively increased expression of ICC-LC below the obstruction.

Conclusion

The expression of ICC-LC shows a uniformly decreasing trend across obstruction when the severity of obstruction is less. Resurgence in the number of ICC-LC below PUJ in subjects with severe obstruction hints at the emergence of a new pacemaker area below severely blocked PUJ akin to that seen in complete heart block patients and deserves early attention.

Evaluation of Interstitial Cells of Cajal-Like Cells at the Pelviureteric Junction in Children with Pelviureteric Junction Obstruction: A Prospective Study and Review of Literature

INTRODUCTION

The etiopathogenesis of pelviureteric junction obstruction (PUJO) has been debated. Recently, the role of interstitial cells of Cajal-like cells (ICC-LC)has been studied and reported to be the cause of this functional obstruction. We studied the histopathology and ICC-LC density at PUJ and compared it with that of PUJ of the control group and distal ureteric margin of the study group.

METHODS

A prospective study was conducted which included PUJO patients in the study group and the renal tumor patients in the control group. Histopathological examination (muscle hypertrophy and fibrosis) and immunohistochemistry (ICC-LC density) were done. The muscle hypertrophy, fibrosis, and ICC-LC density at the PUJ in both the groups were compared. A similar comparison was performed between the findings at the PUJ and the distal margin in the study group.

RESULTS

The study and control groups included 37 PUJO patients and 13 Wilms tumor patients. The ICC-LC density at PUJ in the study group was significantly lower than that in the control group (P < 0.001) and that at the distal resected margin of the study group (P < 0.001). Significantly increased muscle hypertrophy (P < 0.001) and fibrosis (P = 0.002) were seen at PUJ in the study group compared to the control group. No significant association was noted between the ICC-LC density and muscle hypertrophy at PUJ and the distal resected margin in the study group.

CONCLUSION

A significant decrease in the density of ICC-LC and increased fibrosis and muscle hypertrophy at PUJ in children with PUJO play a role in the etiopathogenesis of the disease.

Variations in the Density and Distribution of Cajal Like Cells Associated With the Pathogenesis of Ureteropelvic Junction Obstruction: A Systematic Review and Meta-Analysis

Introduction: Cajal like cells (CLCs) in the upper urinary tract have an ability to generate coordinated spontaneous action potentials and are hypothesized to help propel urine from renal pelvis into the ureter. The objective of this review was to describe the variations in the density and distribution of CLCs associated with ureteropelvic junction obstruction (UPJO). Materials and Methods: Studies comparing the density and distribution of CLCs in the human upper urinary tract in patients with UPJO and healthy controls were included in this systematic review. We searched online electronic databases; Ovid MEDLINE, Scopus, PubMed and Cochrane reviews for the studies published before October 31, 2020. A meta-analysis was conducted to compare the density of CLCs at the ureteropelvic junction (UPJ) in patients with UPJO and matched controls. Results: We included 20 and seven studies in the qualitative and quantitative synthesis, respectively. In majority (55%) CLCs were located between the muscle layers of the upper urinary tract. The CLC density in the UPJ gradually increased with aging in both healthy subjects and patients with UPJO. The pooled analysis revealed that the density of CLCs at the UPJ was significantly low in patients with UPJO compared to the controls (SMD = -3.00, 95% CI = -3.89 to -2.11, p < 0.01). Conclusions: The reduction in CLC density at the UPJ in patients with UPJO suggests a contribution from CLCs in the pathogenesis of UPJO. Since age positively correlates with CLC density, it is imperative to carefully match age when conducting case control studies comparing the CLC density and distribution. Protocol Registration Number: CRD42020219882.

Relation between Cajal Cell Density and Radiological and Scintigraphic Outcomes in Patients with Ureteropelvic Junction Obstruction

INTRODUCTION

In this study, we aimed to investigate the correlation between Cajal cell density and preoperative and postoperative radiological and scintigraphic parameters in ureteropelvic junction obstruction (UPJO).

METHODS

The study group consisted of 41 renal units (38 consecutive patients; 13 female and 25 male) surgically treated for UPJO. UPJ specimens from patients were immuno-stained with CD117 (c-kit) antibody for interstitial Cajal cells (ICCs). The relation between Cajal cell density and preoperative and postoperative radiological and scintigraphic parameters was evaluated.

RESULTS

The mean age of the patients was 8.52 ± 8.86 (0-35) years. The density of Cajal cells was defined in 2 groups for convenient analysis as 0-5 cells (low) in 19 (46.3%) patients and >5 cells (moderate-high) in 22 (53.6%). There was significant difference between the preoperative and postoperative anteroposterior diameters of the related kidneys in both Cajal groups (p = 0.001-low, p = 0.000-moderate-high) independent of Cajal cell density. Regression in hydronephrosis postoperatively was determined in both Cajal groups (77.8%-low, 64.7%-moderate-high); however, there was no difference between them (p = 0.39). Preoperative T1/2 was significantly longer in the low Cajal group (p = 0.02). Postoperative T1/2 decreased in both low (p = 0.000) and moderate-high (p = 0.001) Cajal groups, but no difference was found between them (p = 0.24). There was significant improvement in the kidney differential function after surgery in the low Cajal density group (p = 0.015) while there was no correlation between the scintigraphic success or improvement and Cajal cell density (p = 0.51).

DISCUSSION/CONCLUSION

ICC deficiency/density could not be shown as a predictive factor for the determination of success rate of pyeloplasty. Despite the lack of any evidence for the degree of deficiency as an indicator for the severity of obstruction and prediction of surgical success, further studies are needed for confirmation.

Factors Accountable for Unabated Obstruction Following Pyeloplasty

Purpose:

Split renal function (SFR) and frusemide washout (FWO) are assessed by the DTPA renogram to measure the renal parenchymal functions as well as the evidence of obstruction, both for diagnosis and to treat the pelviureteric junction obstruction. In good number of renal units, both these parameters remain unaltered even after surgery and cause anguish to parents and referring physicians and are usually attributed toward “defective pyeloplasty.” In this study, we have tried to single out the bona fide responsible factor for the bad outcome; either the nonreversible kidney or the restenosis of pyeloplasty.

Patients and Methods:

We studied file of 69 patients in whom a double “J” (DJ) stent was left in situ for internal drainage for a duration of 8 weeks in the postoperative period. DTPA scans were performed preoperative, at 8 weeks with a stent in place, and at 12 and 24 months postremoval of the stent to assess renal function.

Results:

In our study, 45 patients (65.2%) showed improvement either in SRF or in FWO or in both after 8 weeks following pyeloplasty and 24 of 69 units (34.8%) did not show any change in renal function with DJ stent in place. Only in six units (8.7%), out of 69 units had deterioration of renal function after removal of DJ stent.

Conclusions:

In our opinion, no improvement of renal function found in 24 units (34.8%) even with internal drainage with DJ indicates irreversible renal damage. In 45 units (65.2%), renal function reversed after pyeloplasty and DJ stent. However, after the removal of the DJ, functions deteriorated in six units (8.7%) due to restenosis following pyeloplasties.

The prognostic value of histopathological pattern of the pelviureteric junction in the outcome of pyeloplasty in children

Background

The cause of pyeloplasty failure remains unclear; therefore, increasing interest has been directed to identify the reason for dissatisfactory surgical results. Some studies attempted to investigate the role of the histopathological pattern. The aim of the work is to study the correlation between the histopathological pattern of obstructed pelviureteric junction (PUJ) segment and the outcome of pyeloplasty in children with the PUJ.

Methods

Fifty-four patients with pelviureteric junction obstruction (PUJO) were included in the study; patients were evaluated preoperative. All patients were operated by the same surgeon using Anderson–Hynes pyeloplasty; the resected obstructed PUJ segment examined histopathological using light microscope and image analyzer system to identify mean renal pelvis smooth muscle thickness (mRPSMT), collagen-to-smooth muscle ratio and elastin content.

Results

The study includes 50 patients with mean age Mean 24.48 ± 15.3 months. Two patients show no improvement, while 24 improved at 3 months, 16 improved at 6 months, and 8 improved at 12 months. mRPSMT showed significant difference between improvement groups (136.02 ± 44.4, 173.47 ± 49.69 and 258.56 ± 96.82 μm), while elastin content or collagen-to-smooth muscle ratio showed no significant difference.

Conclusions

Our data showed a clear relationship between mRPSMT and the time over which radiological improvement occurs; increase in mRPSMT is associated with a delay in postoperative radiological improvement time. We found no relation between elastin content nor collagen-to-smooth muscle thickness and postoperative improvement course.

Comparison of different pathological markers in predicting pyeloplasty outcomes in children

PURPOSE

To compare the efficacy of pathological markers like Interstitial cells of Cajal (ICC), neurons and Collagen to Muscle ratio (CM ratio), in predicting pyeloplasty outcomes.

METHODS

Histological sections from 31 patients with UPJO were analyzed for ICC & neurons on immuno-histochemistry and CM ratio on Masson's trichrome staining. Post-operative outcomes were analyzed at 1-year follow up; expressed as excellent, moderate or mild improvement, static and deterioration based on the three factors: ultrasound grade, differential renal function and renogram drainage pattern. The pathological findings were correlated with clinical outcomes.

RESULTS

The study group (n = 31) had a mean age 2.9 (0.6) years (M: F = 22:9). UPJ segment had significantly less ICC/neurons and more collagen compared to normal ureter (p = 0.001). Pathological parameters at the anastomosed end of ureter had a better correlation than those at UPJ with clinical outcome. CM ratio with a stronger correlation (r = - 0.94; p = 0.001) was a better predictor of prognosis than ICC (r = 0.76; p = 0.01) or neuron (r = 0.83; p = 0.01) density. ICC >10/HPF, neurons >6/HPF and CM ratio <1.2 at ureteric end anastomosed were predictors of success.

CONCLUSIONS

CM ratio analysis at anastomosed ureter is a superior marker for predicting pyeloplasty outcomes.

LEVEL OF EVIDENCE

Type 2: Development of diagnostic criteria in a consecutive series of patients.

Influence of Interstitial Cells of Cajal in Congenital Ureteropelvic Junction Obstruction

Background:

The etiopathogenesis of congenital ureteropelvic junction obstruction (UPJO) has been inconclusive in spite of the numerous studies carried out to find the possible causative factor. The results of different studies have been conflicting and contradictory. It has been postulated that the interstitial cells of Cajal (ICC) are the pacemaker cells located in the ureteropelvic junction (UPJ) and regulate the peristalsis in this region. Paucity of these cells may be one of the causative factors for congenital UPJO although there is no clear consensus on this issue. Therefore, the present study has been carried out to ascertain the role of ICC as one of the possible etiological factors for congenital UPJO. The aim of this study is to first identify the presence of ICC at UPJ, second to compare the average number of ICC in congenital UPJO with a control population without UPJO, and third to ascertain whether any correlation exists between the number of ICC and postoperative improvement in function of the affected kidney.

Materials and Methods:

A total number of 30 patients who underwent dismembered Anderson-Hynes pyeloplasty for congenital UPJO between June 2016 and November 2017, were compared with seven controls who underwent nephroureterectomy for various other reasons. The specimen was subjected to immunohistochemistry (IHC), and a quantitative comparison was made for the ICC between cases and controls. The preoperative and postoperative function was evaluated by renal diuretic scintigraphy.

Results:

The disease was more common among males in the ratio of 6.5:1, and there was a predominance of the left-sided involvement. In the studied cases, the average number of ICC seen for every high-power field (hpf) was 4.86 ± 0.76/hpf, whereas in control it was 11.74 ± 0.86/hpf (P = 0.04). The postoperative outcome, as measured by the improvement in split renal function, did not have any correlation with the number of ICC.

Conclusion:

The ICC are present at the UPJ and can be detected by immunohistochemistry due to their CD117 positivity. These cells are significantly low at this site in cases of congenital UPJO when compared to controls without any obstruction. The number of ICC bears no correlation to the postoperative improvement in function.

A Rapid Special Staining Technique for Identification of Normal Ureter by Frozen Section in Children With Ureteropelvic Junction Obstruction

BACKGROUND

The exact etiology of ureteropelvic junction obstruction (UPJO) is unknown, and inadequate excision of the narrow segment has been proposed as a cause of failure in 5% to 7% of cases of pyeloplasty.

AIMS

To study whether frozen section can be useful to detect normal ureter distal to UPJO during pyeloplasty.

METHODS

Histological sections from 31 patients with UPJO were analyzed for collagen to muscle ratio (CMR) on conventional (formalin) and rapid (frozen section) Masson's trichrome staining. Pathological findings were correlated with postoperative outcomes analyzed at 1-year follow-up and expressed as excellent, moderate, or mild improvement, static and deterioration based on ultrasound grade, differential renal function, and renogram drainage pattern.

RESULTS

There was a very strong positive correlation (r = .94; P = .001) between CMR by conventional and rapid frozen Masson's trichrome staining. There was a very strong negative correlation between pyeloplasty outcomes and CMR on conventional staining (r = -.94; P = .001) or rapid frozen Masson's trichrome staining (r = -.91; P = .001). Regression analysis revealed that a CMR of 1.2 or less (95% confidence interval: 1.9-0.7) was associated with a successful outcome.

CONCLUSIONS

It is feasible to intraoperatively identify normal ureter distal to UPJO using CMR analysis on the novel rapid frozen section technique reported.