The risks associated with percutaneous native kidney biopsies: a prospective study.

BACKGROUND: The known risks and benefits of native kidney biopsies are mainly based on the findings of retrospective studies. The aim of this multicentre prospective study was to evaluate the safety of percutaneous renal biopsies and quantify biopsy-related complication rates in Italy. METHODS: The study examined the results of native kidney biopsies performed in 54 Italian nephrology centres between 2012 and 2020. The primary outcome was the rate of major complications 1 day after the procedure, or for longer if it was necessary to evaluate the evolution of a complication. Centre and patient risk predictors were analysed using multivariate logistic regression. RESULTS: Analysis of 5304 biopsies of patients with a median age of 53.2 years revealed 400 major complication events in 273 patients (5.1%): the most frequent was a ≥2 g/dL decrease in haemoglobin levels (2.2%), followed by macrohaematuria (1.2%), blood transfusion (1.1%), gross haematoma (0.9%), artero-venous fistula (0.7%), invasive intervention (0.5%), pain (0.5%), symptomatic hypotension (0.3%), a rapid increase in serum creatinine levels (0.1%) and death (0.02%). The risk factors for major complications were higher plasma creatinine levels [odds ratio (OR) 1.12 for each mg/dL increase, 95% confidence interval (95% CI) 1.08-1.17], liver disease (OR 2.27, 95% CI 1.21-4.25) and a higher number of needle passes (OR for each pass 1.22, 95% CI 1.07-1.39), whereas higher proteinuria levels (OR for each g/day increase 0.95, 95% CI 0.92-0.99) were protective. CONCLUSIONS: This is the first multicentre prospective study showing that percutaneous native kidney biopsies are associated with a 5% risk of a major post-biopsy complication. Predictors of increased risk include higher plasma creatinine levels, liver disease and a higher number of needle passes.

Case Report: Optic Atrophy and Nephropathy With m.13513G>A/MT-ND5 mtDNA Pathogenic Variant.

Isolated complex I deficiency represents the most common mitochondrial respiratory chain defect involved in mitochondrial disorders. Among these, the mitochondrial DNA (mtDNA) m.13513G>A pathogenic variant in the NADH dehydrogenase 5 subunit gene (MT-ND5) has been associated with heterogenous manifestations, including phenotypic overlaps of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes, Leigh syndrome, and Leber's hereditary optic neuropathy (LHON). Interestingly, this specific mutation has been recently described in patients with adult-onset nephropathy. We, here, report the unique combination of LHON, nephropathy, sensorineural deafness, and subcortical and cerebellar atrophy in association with the m.13513G>A variant.

Renal involvement in sarcoidosis: histological patterns and prognosis, an Italian survey.

BACKGROUND: Granulomatous interstitial nephritis in sarcoidosis (sGIN) is generally clinically silent, but in <1% causes acute kidney injury (AKI). METHODS: This Italian multicentric retrospective study included 39 sarcoidosis-patients with renal involvement at renal biopsy: 31 sGIN-AKI, 5 with other patterns (No-sGIN-AKI), 3 with nephrotic proteinuria. We investigate the predictive value of clinical features, laboratory, radiological parameters and histological patterns regarding steroid response. Primary endpoint: incident chronic kidney disease (CKD) beyond the 1°follow-up (FU) year; secondary endpoint: response at 1°line steroid therapy; combined endpoint: the association of initial steroid response and outcome at the end of FU. RESULTS: Complete recovery in all 5 No-sGIN-AKI-patients, only in 45% (13/29) sGIN-AKI-patients (p=0.046) (one lost in follow-up, for another not available renal function after steroids). Nobody had not response. Primary endpoint of 22 sGIN-AKI subjects: 65% (13/20) starting with normal renal function developed CKD (2/22 had basal CKD; median FU 77 months, 15-300). Combined endpoint: 29% (6/21) had complete recovery and final normal renal function (one with renal relapse), 48% (10/21) had partial recovery and final CKD (3 with renal relapse, of whom one with basal CKD) (p=0.024). Acute onset and hypercalcaemia were associated to milder AKI and better recovery than subacute onset and patients without hypercalcaemia, women had better endpoints than men. Giant cells, severe interstitial infiltrate and interstitial fibrosis seemed negative predictors in terms of endpoints. CONCLUSIONS: sGIN-AKI-patients with no complete recovery at 1°line steroid should be treated with other immunosuppressive to avoid CKD, in particular if males with subacute onset and III stage-not hypercalcaemic AKI.

[Relevance of an accurate microscopic examination of urinary sediment in a patient after mitral valve surgery].

Hemoglobinuria, clinically revealing as gross hematuria associated with anemia, increased hemolysis indices, acute kidney injury (AKI), can all be caused by mechanical intravascular hemolysis following mitral valve surgery. It can result from factors related to the surgical procedure or acquired later, such as paravalvular leak (PL), whose definite diagnosis is based on transesophageal echocardiography. We report the case of a patient who experienced macrohematuria and AKI, initially attributed to acute glomerulonephritis, two months after mitral valve surgery. Careful microscopic examination of the urinary sediment was a diriment diagnostic tool to differentiate acute renal failure caused by hemoglobinuria from hematuria in the course of acute glomerulonephritis, directing clinicians to investigate post-operative valvular dysfunction. From the literature review we can deduce that, notwithstanding new technologies in cardiac surgery, this rare form of AKI from intravascular hemolysis requires immediate nephrological attention and that the use of microscopic urinary sediment is decisive.

PLA2R Immunohistochemistry Staining in Membranous Glomerulopathy: A Challenging Stain to Interpret But a Potentially Useful Diagnostic Tool.

Circulating autoantibodies to phospholipase A2 receptor (PLA2R-Ab) are detected in >70% of patients with primary membranous glomerulonephritis (MGN). Detection of PLA2R antigen in renal tissue, with immunohistochemistry (PLA2R IHC), strongly correlates with serum PLA2R-Ab, although it is more sensitive. As PLA2R IHC in literature has no univocal interpretation, we suggest reliable criteria for a standard approach for the assessment of immunostaining for differential diagnosis between primary and secondary MGN. We analyzed PLA2R IHC expression in 40 biopsies of patients with MGN and serum PLA2R-Ab titer at the time of biopsy. We carefully evaluated, at high magnification, the immunostaining pattern and distribution, regardless of intensity, in capillary loops, mesangium, and podocytes of all glomeruli.We defined, adopting this approach, positive stain when a granular pattern, coarse and/or fine, diffuse or focal, and global or segmental were observed. Negative stain was defined by mesangial staining, when there was a dirty pattern, or a peripheral staining of capillary loops with a smoky linear pattern. Podocytes showed homogenous cytoplasmatic stain both in positive and negative cases and in external negative controls. We found PLA2R IHC and serum PLA2R-Ab positivity in early-middle stage MGN compared with advanced stage more frequently. Correct stratification of patients with MGN needs PLA2R-Ab detection in serum and renal tissue. PLA2R IHC test, although a challenging stain, can be an easy diagnostic tool but requires reliable interpretation keys for a standard approach to the assessment of immunostaining.

WITHDRAWN: Nephrotic syndrome in primary myelofibrosis with renal extramedullary hematopoiesis and glomerulopathy in the JAK inhibitor era.

Ahead of Print article withdrawn by publisher. The publisher apologizes for any inconvenience this has caused. The article was scheduled for the journal "Clinical Nephrology. Case Studies" (issn 2196-5293). The article is available in PubmedCentral: https://www.ncbi.nlm.nih.gov/pubmed/29350220 
.

Nephrotic syndrome in primary myelofibrosis with renal extramedullary hematopoiesis and glomerulopathy in the JAK inhibitor era.

Primary myelofibrosis (PMF) is an uncommon form of myeloproliferative neoplasm (MPN) characterized by a proliferation of predominantly megakaryocytes and granulocytes in the bone marrow that, in fully-developed disease, is associated with reactive deposition of fibrous connective tissue, extramedullary hematopoiesis (EMH), and splenomegaly. Kidney involvement is rare and clinically presents with proteinuria, nephrotic syndrome, and renal insufficiency. Renal damage can be due to EMH and glomerulopathy. Renal EMH presents three patterns: infiltration of the interstitium with possible renal failure caused by functional damage of parenchyma and vessels, infiltration of capsule and pericapsular adipose tissue, and sclerosing mass-like lesions that can cause hydronephrosis and hydroureter with obstructive uropathy and renal failure. Glomerulopathy associated with PMF is rarely described, ranging from 1 month to 18 years from diagnosis of the neoplasm to renal biopsy. It is characterized by expansion and hypercellularity mesangial, segmental sclerosis, features of chronic thrombotic microangiopathy (TMA), and intracapillary hematopoietic cells infiltrating in absence of immune-mediated glomerulonephritis. We present a nephrotic syndrome in PMF-related glomerulopathy, associated with EMH, without renal failure, in a patient under treatment for 2 years with JAK2 inhibitor ruxolitinib. Despite treatment, the patient died 7 months after renal biopsy. Nephrologists still know very little about this topic and there is no homogeneous data about incidence, pathogenesis, and optimal treatment of this poor prognostic PMF-associated nephrotic syndrome. We focus on data in the literature in the hope of stimulating hematologists, nephrologists, pathologists to future studies about the natural history of renal involvement, useful for optimal management of this rare pathology.

PTPN22 R620W polymorphism in the ANCA-associated vasculitides.

OBJECTIVES: PTPN22 is involved in T-cell activation and its R620W single-nucleotide polymorphism (SNP) has been shown to predispose to different autoimmune diseases. The aims of this study were to investigate the role of the PTPN22 R620W SNP in conferring susceptibility to the ANCA-associated vasculitides (AAVs), and to explore potential associations between the PTPN22 genotype and the disease manifestations. METHODS: PTPN22 R620W SNP was genotyped in a cohort of 344 AAV patients [143 with granulomatosis with polyangiitis (Wegener's) (GPA), 102 with microscopic polyangiitis (MPA) and 99 with Churg-Strauss syndrome (CSS)] and in 945 healthy controls. RESULTS: The frequency of the minor allele (620W) was significantly higher in GPA patients than in controls [P = 0.005, χ(2 )= 7.858, odds ratio (OR) = 1.91], while no statistically significant association was found with MPA or CSS. Among GPA patients, the 620W allele was particularly enriched in ANCA-positive patients as compared with controls (P = 0.00012, χ(2 )= 14.73, OR = 2.31); a particularly marked association was also found with ENT involvement (P = 0.0071, χ(2 )= 7.258, OR = 1.98), lung involvement (P = 0.0060, χ(2 )= 7.541, OR = 2.07) and skin manifestations of all kinds (P = 0.000047, χ(2 )= 16.567, OR = 3.73). CONCLUSION: The PTPN22 620W allele confers susceptibility to the development of GPA (but not of MPA or CSS), and particularly of its ANCA-positive subset.

Renal involvement in systemic amyloidosis--an Italian retrospective study on epidemiological and clinical data at diagnosis.

BACKGROUND: Few data are available on epidemiology and clinical picture of renal involvement in different forms of systemic amyloidosis. METHODS: Patients with biopsy-proven systemic amyloidosis diagnosed in Italy between January 1995 and December 2000 were selected from 49 Nephrology and Internal Medicine Units provided they showed signs characteristic of renal involvement. Clinical and laboratory information were collected by using a specific data form for diagnosis integrated by a questionnaire on diagnostic tools. Collected data were matched both with the Italian Registry of Renal Biopsies (IRRB) and the Registry of the Italian Society of Amyloidosis (SIA) in order to approximate the incidence of the disease. RESULTS: Of all patients, 373 were finally selected throughout Italy with an estimated mean incidence of renal amyloidosis of 2.1 per million population (p.m.p.) per year. Of those, 237 were affected from AL (primary) amyloidosis, 104 from AA (secondary) amyloidosis and 6 from AF (heredofamilial) forms. In 26 cases the type of amyloidosis remained undetermined. Among patients with AL, 36 presented an associated multiple myeloma (MM). Rheumatoid arthritis (RA) was the commonest underlying disease in AA. Median age ranged between 63 and 65 years in all groups. Males were prevalent in AL and females in AA. The main clinical features of renal involvement were represented by nephrotic syndrome and renal failure observed in 59 and 54% of cases, respectively. The presence of a lambda light chain, either in serum or urine was significantly associated to a more elevated urinary protein loss and to a reduced renal function. Patients with AA showed a worse renal function at presentation than patients with AL, possibly due to a late diagnosis and/or referral to nephrology units. Diagnosis was obtained by renal biopsy in 315 cases, by abdominal fat tissue (AFT) aspiration/biopsy in 156 patients and by other organ biopsies in 47 patients. Characterization of deposits was extremely variable among referring centres. CONCLUSIONS: Our results point to an increased incidence of renal amyloidosis observed in Italy over the period 1996-2000 with AL as the prevalent type. Characterization of amyloid deposits still remains the major diagnostic challenge of the disease. The institution of networks dedicated to rare diseases is strongly recommended in order to effectively afford this challenge.