|Year : 2020 | Volume
| Issue : 1 | Page : 37-41
Clinical, morphologic and histological features of chronic pyelonephritis: An 8-year review
Babatunde Lawrence Ademola1, Akinfenwa T Atanda2, Sani A Aji3, Aliyu Abdu1
1 Department of Medicine, Aminu Kano Teaching Hospital, Kano, Nigeria
2 Department of Pathology, Aminu Kano Teaching Hospital, Kano, Nigeria
3 Department of Surgery, Aminu Kano Teaching Hospital, Kano, Nigeria
|Date of Submission||22-Jul-2019|
|Date of Acceptance||27-Oct-2019|
|Date of Web Publication||14-Jan-2020|
Dr. Babatunde Lawrence Ademola
Department of Medicine, Aminu Kano Teaching Hospital, Kano
Source of Support: None, Conflict of Interest: None
Background: Urinary tract infection (UTI), especially pyelonephritis when inadequately treated may culminate in end-stage renal disease. The study aims to evaluate the risk factors for and clinico-pathologic features of chronic pyelonephritis (CPN) among patients in Aminu Kano Teaching Hospital, Kano, in North-Western Nigeria. Materials and Methods: Data on cases diagnosed as CPN between 2010 and 2017 in the study centre were retrieved from archives and analysed for risk factors and clinic-pathologic features. Results: Forty-three cases of CPN were diagnosed in the study period and comprised 24 males and 19 females, with a male: female ratio of 1.3:1. The ages ranged from 3 to 80 years with a mean age of 37.0 ± 19.6 years. Urinary tract obstruction, poorly treated UTI, HIV infection and polycystic kidney disease were the risk factors in 21 (49%), 15 (35%), 6 (14%) and 1 (2%) cases, respectively. Proteinuria was seen in 10 (23.3%) of the patients, hypertension in 7 (16.3%) and haematuria in 3 (7.0%) of cases. Nephrectomy was done in 17 (39.5%) of the 43 CPN cases, indications for surgery were pus-filled, non-functioning kidneys. The diameters of the removed kidneys ranged from 10 to 28 cm and they weighed between 140 g and 2500 g. Scarring, reported in 79.0% of patients, was the most common pathological finding, followed by pus casts in 48.8% and focal segmental glomerulosclerosis in 27.9%. No statistically significant difference was found between age or gender and aetiology or risk factors of the disease (P > 0.05). Conclusion: CPN with pus-filled and non-functioning kidneys is a common indication for nephrectomy. Urinary tract obstruction, poorly treated UTI, and HIV infection were major risk factors seen in this environment. To prevent this complication there is a need for better training of clinicians in the diagnosis and adequate treatment of UTI.
Keywords: Chronic pyelonephritis, infection, nephrectomy
|How to cite this article:|
Ademola BL, Atanda AT, Aji SA, Abdu A. Clinical, morphologic and histological features of chronic pyelonephritis: An 8-year review. Niger Postgrad Med J 2020;27:37-41
|How to cite this URL:|
Ademola BL, Atanda AT, Aji SA, Abdu A. Clinical, morphologic and histological features of chronic pyelonephritis: An 8-year review. Niger Postgrad Med J [serial online] 2020 [cited 2020 Apr 6];27:37-41. Available from: http://www.npmj.org/text.asp?2020/27/1/37/275803
| Introduction|| |
Pyelonephritis is defined as inflammation of the renal parenchyma and is derived from the Greek words 'pyelo' (pelvis), 'nephros' (kidney) and 'itis' (inflammation). It may be acute and characterised by features of inflammation and sometimes the triad of fever, costovertebral angle pain and nausea (or vomiting). It may also present as chronic pyelonephritis (CPN) which manifests with repeated acute episodes or occurs insidiously over several years and is only discovered as end-stage renal disease (ESRD). The term CPN encompasses the not otherwise specified variants such as xanthogranulomatous pyelonephritis (XGP) and emphysematous pyelonephritis. Most cases of CPN have been linked to vesico-ureteric reflux in the young and recurrent infections, but the entity represents an end-stage disease of many chronic inflammatory renal processes leading to chronic kidney disease. Indeed, it is one of the relative indications for a pre-emptive renal transplant.
Worldwide, CPN accounts for about 4%–6% of patients requiring dialysis for ESRD., Even though incidence and prevalence data on the disease is scanty, available literature estimates that CPN occurs at a rate of about 1–2/1000 women and under 0.5/1000 males. In Nigeria, Ulasi and Ijoma have reported it, co-morbid with other diseases, in 16% of 49 autopsied cases, whereas Nggada et al. in Northern Nigeria reported it as accounting for 28.6% of all nephrectomy cases. This study aims to evaluate the clinical and morphological profile of the disease with a view to identifying associated risk factors and thus aid a better understanding of the disease.
| Materials and Methods|| |
This was a retrospective review of all cases of CPN diagnosed between January 2010 and December, 2017 at the study centre. Data were retrieved from case files of the patients and included age, gender, diagnosis method (nephrectomy/radiology/biopsy), risk factors and gross morphologic and histologic features. The data were extracted and statistically managed with IBM SPSS Statistics for Windows, Version 24.0. IBM Corp. Armonk, NY, USA. Percentages and proportions were used to describe categorical data while mean (standard deviation) was used for continuous data. A chart was used for graphical illustration. Pearson's Chi-square was used to assess categorical variables with aetiology and risk factors and a value of P < 0.05 was considered to be statistically significant.
The diagnosis of CPN was made based on a history of infection of the urinary tract together with changes on excretory urography, which included distortion and clubbing of calices with focal parenchymal narrowing; with/without histological evidence of pyelonephritis. Incompletely treated urinary tract infection (UTI) was defined as persistent UTI with microbiological confirmation on urine microscopy which was treated for less than the recommended duration of therapy (<3 days for lower UTI and 2 weeks for upper UTI) with appropriate antibiotic therapy. Significant proteinuria was defined as the presence of more than 500 mg/day of protein in the urine (≥2 + dipstick protein) on more than one occasion. Hypertension was defined as blood pressure more than or equal to 140/90 mmHg on more than one occasion.
| Results|| |
In the 8 years reviewed, 43 cases were diagnosed as CPN (irrespective of risk factor) or co-morbid with another lesion as seen in two cases of polycystic kidney disease (PKD). The CPN cases comprised 24 males and 19 females, with a Male: Female ratio of 1.3:1. The ages ranged from 3 to 80 years with a mean age of 37.0 ± 19.6 years. Age of patients with the disease rose steadily from age <10 years to a peak in the 30–39 years age group and fell progressively but only to reach a smaller peak in the 60–69 years age group [Figure 1]. Nephrectomy for ESRD with pus-filled and non-functioning kidneys secondary to CPN was done in 17 (39.5%) of the 43 cases and accounted for 29% of all indications for nephrectomy done in the study period.
|Figure 1: Age distribution of the male and female chronic pyelonephritis cases|
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Urinary tract obstruction, incompletely treated UTI, HIV infection and PKD were the risk factors in 21 (49%), 15 (35%), 6 (14%) and 1 (2%) of cases, respectively [Table 1]. Of obstructive causes, genitourinary tract tumours, including prostatic and ovarian were the most common causes in men and women, respectively. These were followed by 3 (7%) cases of ureteric schistosomiasis, 4 (9.3%) cases of ureteric stones (male: female 1:1) and vesico-ureteric reflux in 2 (4.7%) male children. Incompletely treated UTI was the cause of ascending infection in 15 (35%) of cases, while immunosuppression due to HIV infection was seen in 6 (14%) cases. In two male children, CPN complicated PKD.
|Table 1: Risk factors for chronic pyelonephritis relative to age and gender|
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Clinically proteinuria, hypertension and haematuria were seen in 10 (23.3), 7 (16.3) and 3 (7.0%) of the cases, respectively. The surgical nephrectomy specimens were all unilateral and had weights ranging from 140 g to 2500 g. Three (17.6%) of the 17 nephrectomy specimens were shrunken and had maximal kidney length <10 cm, while the kidneys were normal to enlarge in the remaining 14 cases. These cases also showed loss of cortico-medullary differentiation and dilatation of the pelvi-calyceal system [Figure 2]. Histological examination showed scarring in 34 (79.0%) of the cases and xanthogranulomatous change in 5 (11.6%) of cases. Pus casts, focal segmental glomerulosclerosis (FSGS) and arteriolosclerosis were also seen in 48.8%, 27.9% and 16.3% of the cases, respectively [Table 2]. No statistically significant difference was found between age or gender and aetiology or age or gender and risk factors of the disease (P > 0.05).
|Figure 2: Transection of hydronephrotic kidney showing pelvi-calyceal dilatation and a stone causing obstruction of the ureter (arrow)|
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|Table 2: Clinico-pathologic features of the chronic pyelonephritis cases|
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| Discussion|| |
CPN, by itself or co-morbid with other renal lesions, accounted for 29% of renal biopsies in the present study. This is lower than the 54.3% reported by Divyashree et al., 62.8% by Aiman et al. and 78.6% by Awasthi; but similar to the 28.4% documented by Narang et al. and the 28.6% by Nggada et al. All these studies appear to corroborate the observation that CPN is one of the most common indications for renal biopsy and nephrectomy. The preponderance of cases of CPN in the 20–40 age group in this study is similar to that reported by Aiman et al. and reflects the relatively low frequency of childhood risk factors such as vesico-ureteric reflux as seen in this study and that reported by Eke and Eke as well as late presentation in the study setting. The mean age of 37.0 ± 19.6 years in this report is, however, slightly younger than the 44.4 ± 14.8 years reported by Awasthi as well the 45 years reported by Narang et al.
The finding of more cases of male gender-dominated risk factors including ureteric stones and reflux and the other fairly evenly distributed risk factors may explain the higher male: female ratio (1.3:1) in the present study. This is in consonance with reports by most other studies albeit with slightly different magnitude.,,, Obstructive uropathy seen in 49% of our cases was the most common risk factor for CPN in this study. However, while Halle et al. in Cameroon reported a mean age of 50 ± 18 years for their obstructive cases, the bulk of patients in the present study were ≤40 years. The high frequency of urolithiasis (19.1%) as a cause of obstructive uropathy seen in the index series is higher than the 11.2% frequency in the study by El Imam et al. but lower than the 35% reported by Halle et al. With regard to this variability in the incidence of urolithiasis, López and Hoppe in an extensive review of the subject have shown that the incidence of urolithiasis in a given population is dependent on their geography, race, socio-economic status and diet.
Inadequate fluid intake was particularly an important risk factor for urolithiasis, as described by Odoemene et al. in Southern Nigeria; Aji et al., and Emokpae and Gadzama, both in our centre; and Mungadi et al., also in the hotter northern Nigeria. All these studies also reported a male preponderance of up to six times compared to females, thus gender may also be added as a risk factor of urolithiasis in our region of the world. This may be related to lower exposure to sunlight and hence lower risk of dehydration in our women than the men who usually spend more time outdoors. Even though Emokpae and Gadzama found that calcium was predominant in 86.2% of the stones analysed, Aji et al. in their own study, found all patients had normal serum levels for calcium, phosphate and uric acid and a high frequency of infection with Escherichia More Details coli. Fifty-six (73.7%) patients in their study had stones in the upper urinary tract and 20 (26.3%) in the lower urinary tract.
Ureteric schistosomiasis was the second-most common cause of non-neoplastic obstructive uropathy in this study. The mortality rate due to non-functioning kidney from chronic infection with schistosomiasis has been put at about 150,000/year. The male: female ratio of 2:1 as well as preponderance in individuals younger than 40 years found in this study reflect the reported epidemiology of the infestation in our geographic area. Even though urine examination for ova of Schistosoma ova is diagnostic and fairly easy to carry out, shed ova may not be present in urine in chronic cases. In addition to this, resistance of the parasite to praziquantel, the primary drug of choice, appears to be emerging, with hitherto treated patients presenting with complications of progressive disease, thus necessitating repeated dosing.,,
Vesico-ureteric reflux was present in two male patients in this report and was another important non-neoplastic risk factor for CPN in this study. These followed posterior urethral valves with late presentation as observed by Okafor et al. in Nigeria. Yilmaz et al. found vesicoureteral reflux (VUR) and renal scarring in 30.9% and 19.4%, respectively, of 300 children studied; this is in addition to others who have found VUR as the most common risk factor associated with paediatric chronic kidney diseases.
The neoplastic causes of obstructive uropathy resulting in CPN in the present study included huge ovarian masses and benign prostatic hypertrophy, as well as cervical cancer and bladder cancer. In the study by El Imam et al., tumours constituted 20% of causes of obstruction. The higher frequency (32.6%) in the index study reflects late presentation by tumour-bearing patients in our local setting. Thus prompt relief of the obstruction and definitive treatment of the aetiologic tumour cannot be effected. Compounding the problem is that cases caused by unilateral factors are also likely to present late because the patient can still 'make' urine.
Incompletely treated UTI seen in 35% of patients was surmised as the risk factor for CPN in the present study. In the geographic location of the present study, several factors may be responsible for this. These include high prevalence of extended-spectrum β-lactamase producing enterobacteriacae in isolates from UTI in our community-based study; antimicrobial misuse by the general populace predisposing to the emergence of resistant strains and high prevalence of asymptomatic bacteruria in our setting. Thus, concerted efforts need to be made in developing new diagnostic and therapeutic strategies, locally and internationally.
The pattern of mortality in HIV-positive individuals is experiencing a shift from opportunistic infection-related to chronic diseases-related, not only in developed countries but also in developing countries. However, the risk factors for chronic renal diseases, including late HIV diagnosis, HIV drug-related toxicity and hypertension as well as genetic susceptibility, appear to be more prevalent in sub-Saharan Africa., Although the number of cases of HIV-related CPN in this study are fewer, the higher frequency of 14% compared to the 7.9% reported by Wyatt et al. in a Caucasian population may reflect racial factors in chronic kidney disease.
Clinical presentation of cases of CPN may be protean and mistaken for nephrotic syndrome. Persistent proteinuria, which has been explained by exudation of protein-rich fluid out of the persistently affected kidney, was the mode of presentation in 23.3% of patients. This, together with hypertension has also been reported by others in their study of patients with CPN. Based on the latter study, the authors concluded that chronic pyelonephritic patients over the age of 18 years presenting to nephrologists with proteinuria and/or hypertension with a serum creatinine ≤90 μmol/l may be reassured that the chances of developing end-stage renal failure in the future are very small if properly followed up. Three percentage of our index cases presented with haematuria; however, these were cases of schistosomiasis. Thus, a heightened index of suspicion for these modes of presentation is essential for prompt and appropriate intervention.
Based on the study by Okeke et al. on renal dimensions among Nigerians, nephrectomy specimens were considered shrunken if <10 cm in length, and this was found in 17.6% of the kidney specimens in the present study and is comparable to the 20.2% reported by Divyashree et al. This has implication for the radiological diagnosis of early cases where atrophy may not be advanced or in Stage I hydronephrotic cases. Scarring and FSGS [Figure 3] seen in the present study is also similar to that described by others and testament to delays in seeking appropriate treatment.
|Figure 3: Marked tubular atrophy with casts, interstitial inflammation and fibrosis and a sclerotic glomerulus (arrow) with peri-glomerular fibrosis (H and E, ×40)|
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XGP was seen in 5 (11.6%) of cases in the index study. While a study with a larger sample size has described a female preponderance, ours (male:female ratio of 1:1), as well as that of others, have found this entity to also be common in males. The clinical significance of this variant of pyelonephritis lies in its differential diagnosis clinically and radiologically as perinephric abscess or renal cell carcinoma and histologically as a clear cell carcinoma., Fine-needle aspiration cytology and computed tomographic scans have, however, been found useful in the proper evaluation of these cases, especially in the context of ureteric stones., This association with ureteric stones was also found by the present study.
The prevention, detection and management of CPN will require intensive efforts by multiple specialties, and thus, it is a meeting point for nephrologists, surgeons and pathologists. It is indeed a reason for more collaboration between specialists.
| Conclusion|| |
This study, unlike those from more developed countries, finds adults younger than 40 years of age to be more commonly affected by CPN, with incompletely treated infective aetiology and late presentation characterising most of the cases.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]