Clinicopathological characteristics and disease chronicity in native kidney biopsies in Flanders

Background

The Flemish Collaborative Glomerulonephritis Group (FCGG) registry provides complete population data on kidney disease epidemiology in the region of Flanders (Belgium), as it captures all native kidney biopsies performed in its population of 6.5 million inhabitants.

Methods

From 2017 until 2019, 2054 adult kidney biopsies were included from 26 nephrology centers (one biopsy per patient). Data on nephrotic and nephritic syndrome were available in 1992 and 2026 biopsies, respectively. In a subgroup of 898 biopsies containing ≥10 glomeruli from 2018 to 2019, disease chronicity was graded using the Mayo Clinic Chronicity Score (MCCS). The association between clinical variables and MCCS was determined using simple and multiple linear regression models.

Results

Nephrotic syndrome (present in 378 patients, 19.0%) was most frequently caused by minimal change disease in younger patients (18-44 years), membranous nephropathy in older patients (45-74 years) and amyloidosis in the elderly (>75 years). Nephritic syndrome (present in 421 patients, 20.8%) was most frequently caused by immunoglobulin A nephropathy (IgAN) in younger patients (18-64 years) and ANCA-associated vasculitis (AAV) in older patients (>64 years). AAV and IgAN were the most frequent underlying diagnoses in biopsies in which crescents were identified. In multivariable analysis, acute and chronic kidney disease and diagnoses of diabetic kidney disease, nephrosclerosis and hyperoxaluria/hypercalcemic nephropathy were associated with the highest MCCS increases.

Conclusions

The FCGG registry validates data from previous Western European registries and provides a snapshot of disease chronicity in the whole biopsied Flemish population.

Epidemiology of native kidney disease in Flanders: results from the FCGG kidney biopsy registry

Background

The Flemish Collaborative Glomerulonephritis Group (FCGG) registry is the first population-based native kidney biopsy registry in Flanders, Belgium. In this first analysis, we report on patient demographics, frequency distribution and incidence rate of biopsied kidney disease in adults in Flanders.

Methods

From January 2017 to December 2019, a total of 2054 adult first native kidney biopsies were included. A ‘double diagnostic coding’ strategy was used, in which every biopsy sample received a histopathological and final clinical diagnosis. Frequency distribution and incidence rate of both diagnoses were reported and compared with other European registries.

Results

The median age at biopsy was 61.1 years (interquartile range, 46.1–71.7); male patients were more prevalent (62.1%) and biopsy incidence rate was 129.3 per million persons per year. Immunoglobulin A nephropathy was the most frequently diagnosed kidney disease (355 biopsies, 17.3% of total) with a similar frequency as in previously published European registries. The frequency of tubulointerstitial nephritis (220 biopsies, 10.7%) and diabetic kidney disease (154 biopsies, 7.5%) was remarkably higher, which may be attributed to changes in disease incidence as well as biopsy practices. Discordances between histopathological and final clinical diagnoses were noted and indicate areas for improvement in diagnostic coding systems.

Conclusions

The FCGG registry, with its ‘double diagnostic coding’ strategy, provides useful population-based epidemiological data on a large Western European population and allows subgroup selection for future research.

Intraoperative frozen section histopathology for the diagnosis of periprosthetic joint infection in hip revision surgery: the influence of recent dislocation and/or periprosthetic fracture

AIMS

To evaluate the accuracy of intraoperative frozen section histopathology for diagnosing periprosthetic joint infection (PJI) during hip revision surgery, both for patients with and without recent trauma to the hip.

PATIENTS AND METHODS

The study included all revision total hip replacement procedures where intraoperative frozen section histopathology had been used for the evaluation of infection in a single institution between 2008 and 2015. Musculoskeletal Infection Society criteria were used to define infection. 210 hips were included for evaluation. Prior to revision surgery, 36 hips had a dislocation or a periprosthetic fracture (group A), and 174 did not (group B).

RESULTS

The prevalence of infection was 14.3% (5.6% in group A and 16.1% in group B). Using Feldman criteria, the sensitivity of histopathology was 50.0%, specificity 47.1%, positive predictive value 5.3% and negative predictive value 94.1% in group A. The sensitivity of frozen section histopathology was 75.0%, specificity 96.5%, positive predictive value 85% and negative predictive value 95.3% in group B.

CONCLUSIONS

Intraoperative frozen section histopathology is reliable for the diagnosis of PJI if no dislocation or periprosthetic fracture has occurred prior to hip revision surgery.

Anisometric Cell and Dysplastic Lipomas in a Retinoblastoma Patient

Anisometric cell lipoma (ACL) and dysplastic lipoma (DL) are underrecognized subtypes of benign lipomatous tumors, with wide variation in cell size, microscopic fat necrosis, and no or mild nuclear changes (DL). ACL/DL appear more commonly in retinoblastoma patients, in whom an increased incidence of lipomas has been established. The occurrence of ACL/DL in retinoblastoma patients suggests that RB1 aberrations play a role in its pathogenesis, similar to spindle cell/pleomorphic lipoma. In this article, we present a patient with a history of retinoblastoma with multiple lipomas histologically consistent with ACL/DL. Analysis of the lipomas supports involvement of RB1 in the development of ACL/DL. Dysplastic changes were only seen in a single lipoma, which harbored an additional TP53 mutation. While providing further support for the occurrence of ACL/DL in retinoblastoma patients, we also suggest that DL is an ACL with TP53 mutation.

Safety and sample adequacy of renal transplant surveillance biopsies

PURPOSE

To report on the safety and adequacy of surveillance biopsy for detecting subclinical lesions in clinically stable renal grafts.

MATERIALS AND METHODS

We established an in-patient surveillance biopsy program with the elective performance of a renal transplant biopsy during the first year after renal transplantation. All biopsies in our centre were performed or supervised by the same operator. Patients were admitted to the hospital the day of biopsy and were discharged after 24h of observation. All patients were biopsied in supine position, using a 16-gauge needle with a spring-loaded gun (Bard) under real-time ultrasound guidance. Complication rates were retrospectively scored using the patients' charts and blood counts before and after biopsy. Major complications were defined as those requiring an intervention for resolution, a transfusion of blood products or an invasive procedure (angiography or surgery), and those that led to acute renal obstruction or failure, septicaemia, graft loss or death. In all other cases complications were considered minor. An adequate biopsy was defined as the presence of 7 or more glomeruli and at least one artery in the biopsy specimen.

RESULTS

We performed 282 surveillance biopsies in 248 patients between January 2006 and December 2011. None of the complications were major. We observed 6% minor complications (n = 17). 5.6% (n = 16) of the complications were related to bleeding, with macroscopic haematuria as the most common condition (n = 10; 3.5%), followed by pain (n = 6; 2.1%) eighter due to a perinephric hematoma (n = 5) or a subcutaneous hematoma (n = 1). The biopsies contained a median number of 9 glomeruli (range 0-39) with 70% of biopsies containing at least 7 glomeruli and one artery.

CONCLUSION

The procedure for taking surveillance biopsies was proven to be safe. There were no major complications and only rare minor complications. The majority of the samples were adequate for histological examination.