Dialysis-associated acquired cystic kidney disease imitating autosomal dominant polycystic kidney disease in a patient receiving long-term peritoneal dialysis

Contrast-enhanced ultrasound of renal masses in the pre-transplant setting: literature review with case highlights

With the rising incidence of chronic kidney disease worldwide, an increasing number of patients are expected to require renal transplantation, which remains the definitive treatment of end stage renal disease. Medical imaging, primarily ultrasonography and contrast-enhanced CT and/or MRI, plays a large role in pre-transplantation assessment, especially in the characterization of lesions within the native kidneys. However, patients with CKD/ESRD often have relative contraindications to CT- and MR-contrast agents, limiting their utilization within this patient population. Contrast-enhanced ultrasound (CEUS), which combines the high temporal and spatial resolution of ultrasonography with intravascular microbubble contrast agents, provides a promising alternative. This review aims to familiarize the reader with the literature regarding the use of CEUS in the evaluation of cystic and solid renal lesions and provide case examples of its use at our institution in the pre-transplant setting.

Increased prevalence of kidney cysts in individuals carrying heterozygous COL4A3 or COL4A4 pathogenic variants

BACKGROUND

Clinical variability among individuals with heterozygous pathogenic/likely pathogenic (P/LP) variants in the COL4A3/COL4A4 genes (also called autosomal dominant Alport syndrome or COL4A3/COL4A4-related disorder) is huge; many individuals are asymptomatic or show microhematuria, while others may develop proteinuria and chronic kidney disease (CKD). The prevalence of simple kidney cysts (KC) in the general population varies according to age, and patients with advanced CKD are prone to have them. A possible association between heterozygous COL4A3, COL4A4 and COL4A5 P/LP variants and KC has been described in small cohorts. The presence of KC in a multicenter cohort of individuals with heterozygous P/LP variants in the COL4A3/COL4A4 genes is assessed in this study.

METHODS

We evaluated the presence of KC by ultrasound in 157 individuals with P/LP variants in COL4A3 (40.7%) or COL4A4 (53.5%) without kidney replacement therapy. The association between presence of KC and age, proteinuria, estimated glomerular filtration rate (eGFR) and causative gene was analyzed. Prevalence of KC was compared with historical case series in the general population.

RESULTS

Half of the individuals with P/LP variants in COL4A3/COL4A4 showed KC, which is a significantly higher percentage than in the general population. Only 3.8% (6/157) had cystic nephromegaly. Age and eGFR showed an association with the presence of KC (P < .001). No association was found between KC and proteinuria, sex or causative gene.

CONCLUSIONS

Individuals with COL4A3/COL4A4 P/LP variants are prone to develop KC more frequently than the general population, and their presence is related to age and to eGFR. Neither proteinuria, sex nor the causative gene influences the presence of KC in these individuals.

Frequency of Acquired Renal Cystic Disease in Patients on Long-Term Hemodialysis and Associated Renal Cell Carcinoma

Background

Acquired cystic renal disease is one of the complications of end-stage renal disease (ESRD) patients on dialysis. We aimed to define the prevalence of acquired cystic renal disease in a dialysis center in a tertiary care setup in Pakistan.

Materials and methods

We conducted a cross-sectional study of 246 patients with ESRD from October 1, 2017, to March 30, 2018. We collected patient demographic data, comorbidities, duration (years), frequency (sessions/week), length of each dialysis session (hours), ultrasound findings, cystic renal disease occurrence, and associated complications for analysis.

Results

Our patient population consisted of 115 women (46.7%) and 131 men (53.3%) and had a mean age of 55.9 ± 15.1 years. Thirty-seven patients were on dialysis for one year, 78 (31.7%) for two years, and 131 (53.3%) for three or more years, as its more common with increasing duration. The mean dialysis duration was 2.3 ± 0.7 years. Of 246 patients, 49 (19.9%) had acquired cystic renal disease.

Conclusions

Given improved health care facilities, an increasing number of patients have a good survival on dialysis and develop long-term complications associated with end-stage renal disease, such as acquired cystic renal disease. Because the acquired renal cystic disease is associated with renal cell carcinoma, physicians should evaluate dialysis patients for renal cell carcinoma, especially after three to five years of dialysis.

Acquired Cystic Kidney Disease: A Hidden Complication in Children on Chronic Hemodialysis

Objective

To determine the frequency of acquired cystic kidney disease (ACKD) in children on chronic hemodialysis.

Material and methods

In this single-center cross-sectional study, 150 children were included who were on chronic hemodialysis for six months. Ultrasound was done to see the renal cysts. Cystic changes that could not fulfill the criteria for ACKD were also noted and analyzed.

Results

The mean age was 14.5 ± 3.5 years, of these 63 (42%) were males. Acquired cysts were detected in 53 (35%) of the patient and 18 patients (12%) had solitary cysts. The distribution of these entities was similar across all age groups. The underlying etiologies in the descending order were unknown 64 (43%), stone disease 31 (21%), each of the congenital anomalies of the kidney and urinary tract, and glomerulonephritis 23 (15%), and others nine (6%). A higher frequency of ACKD was detected in the children on renal replacement therapy for more than two years (33 out of 53 children, 63% with a p-value of 0.004).

Conclusion

The ACKD was found in one-third of our hemodialysis children and its frequency increases with the duration of hemodialysis. This percentage may not reflect the true prevalence as there is a lack of consensus on the definition of ACKD. Periodic assessment of chronic kidney disease patients for the development of ACKD especially on chronic hemodialysis is required to reduce the morbidity.

Acquired cystic kidney disease: an under-recognized condition in children with end-stage renal disease

Acquired cystic kidney disease (ACKD) is a condition that occurs predominantly in patients with end-stage renal disease (ESRD). In contrast to hereditary cystic kidney disease, ACKD is characterized by the presence of multiple small cysts in bilaterally small kidneys. Limited pediatric data suggest a high incidence (21.6-45.8%) of ACKD in children on dialysis, comparable to that in adults, with an increased frequency associated with a longer duration of dialysis. Recent research has shed light on the pathogenesis of ACKD, such as activation of proto-oncogenes. Although most patients with ACKD are asymptomatic, the condition can be complicated by renal cell carcinoma. Routine surveillance should therefore be considered in at-risk populations.

Diagnosing nonneoplastic lesions in nephrectomy specimens

CONTEXT

Nonneoplastic changes are often identified in nephrectomy specimens removed for renal neoplasms. Although they may be of prognostic or therapeutic importance, they are often overlooked. Nephrectomy is also performed for nonneoplastic lesions, the most frequent of which are urinary obstruction and end-stage renal disease, but the tissue diagnosis of these conditions and the implicated clinicopathologic correlation may not be well appreciated.

OBJECTIVE

To outline these nonneoplastic lesions with special attention to important diagnostic caveats and clinicopathologic correlations.

DATA SOURCES

The presented information was derived from literature, personal experience, and review of case materials at the authors' institutions.

RESULTS

Nonneoplastic lesions are seen in most (90%) nephrectomy specimens removed for renal neoplasms. Although these lesions span the spectrum of "medical" kidney diseases, the most frequent of them are hypertensive nephrosclerosis and diabetic nephropathy. Recognition of these diseases is important because they are often first diagnosed and later confirmed clinically. Furthermore, the severity of these lesions may predicate both short- and long-term renal function and thus help guide treatment. Among conditions that necessitate nephrectomy, advanced urinary obstruction, end-stage renal disease, and end-stage renal disease with acquired cystic changes are probably the most frequent. These conditions have characteristic morphologic features, but they may be associated with superimposing lesions previously not well described. These superimposing lesions may create diagnostic confusion; yet, some of them are the reason for nephrectomy. Thus, acute bacterial infection, urine polyp, granulomatous pyelitis, papillary necrosis, massive bleeding, and renal dysplasia can develop against the background of obstructive nephropathy. Renal neoplasms may develop from the background of end-stage renal disease without cystic changes. A renal neoplasm or massive bleeding with or without neoplasm is usually the reason for nephrectomy in kidney with acquired cystic kidney diseases. Thus, while nonneoplastic changes are frequent in nephrectomy specimens, they are often unrecognized. Awareness of these conditions and a familiarity with their diagnostic features as well as the implicated clinicopathologic correlation should help obviate this diagnostic problem.

Polycystic kidneys: a cautionary story

We describe the imaging appearances of a patient with bilateral, synchronous, multiloculated renal cell carcinoma with a predominantly cystic nature. The patient had progressive chronic renal failure. He was initially erroneously diagnosed as having autosomal dominant polycystic kidney disease (ADPKD) on the basis of the imaging findings. We believe this to be the first report describing bilateral synchronous renal carcinomas replacing the renal parenchyma imitating ADPKD.

Renal cystic neoplasms and renal neoplasms associated with cystic renal diseases: pathogenetic and molecular links

Cystic renal neoplasms represent an isolated cystic mass not accompanied by cystic change of the renal parenchyma. Although cystic change may be seen in any type of renal neoplasm, a few (i.e., cystic renal cell carcinoma, cystic nephroma, cystic partially differentiated nephroblastoma, mixed epithelial and stromal tumor) are characterized by constant cystic change that may involve the entire tumor. Cystic kidney disease is characterized by cystic change, which usually involves the kidneys in a bilateral and diffuse pattern, does not create a discreet mass, and is due to hereditary or developmental conditions. Some of the cystic kidney diseases are not known to give rise to renal neoplasm; others such as autosomal polycystic kidney disease or multicystic dysplastic kidney may fortuitously coexist with renal neoplasms. Three conditions (acquired cystic kidney disease, tuberous sclerosis, and von Hippel-Lindau disease) are associated with renal neoplasms with such a high frequency that they are considered preneoplastic. This article reviews the differential diagnoses among cystic neoplasms. It also focuses on the underlying genetic and molecular mechanisms for the relationship between cystic renal diseases and renal neoplasms.