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BACKGROUND AND AIMS Acute interstitial nephritis (AIN) represents an important cause of acute kidney injury. The most common etiology of AIN is drug-induced disease. Definitive diagnosis of AIN requires renal biopsy. Despite this, there is a lack of consensus regarding precise histological diagnostic criteria, and the clinical significance of common histological findings is uncertain. The aim of this study was to explore the histological characteristics of drug-induced AIN and to evaluate their impact on the renal outcome. METHOD We conducted a retrospective study that included patients with biopsy proven drug-induced AIN, followed in the department of nephrology of Charles Nicolle hospital in Tunis during the period between 1990 and 2019. Histological diagnosis of AIN was based on the presence of an interstitial inflammatory cell infiltrate with or without fibrosis. RESULTS During the period of the study, we collected 69 cases of biopsy proven AIN. The diagnosis of drug-induced AIN was performed in 23 patients (33%), with a medium age of 35 years. In eight patients (35%), nonsteroidal anti-inflammatory drugs were the culprit, followed by antibiotics in six patients (26%) and other drugs in three cases (13%). In six patients (26%), no single drug could be identified as the culprit, and these were classified as multidrug causes. The presence of acute kidney disease was the main indication for the kidney biopsy. All cases were characterized by a prominent tubulointerstitial inflammatory cell infiltrate. Interstitial infiltration was mild in three cases (13%), moderate in five cases (17%) and severe in 15 cases (65%). The interstitial infiltrate consisted predominantly of lymphocytes. The presence of eosinophils has been noted in 10 cases (43%). Interstitial granulomas were noted in two patients (8%). Interstitial edema and tubulitis were observed in 13 (56%) and 6 cases (26%), respectively. In seven patients (30%) interstitial fibrosis was present, and four patients (17%) had mild-to-moderate tubular atrophy, whereas tubular necrosis was present in seven cases (30%). After a mean follow up of 24 months, eight patients (35%) progressed to chronic kidney disease. Histological factors associated with poor renal outcome, were interstitial fibrosis (P ˂ 0.001) and tubular atrophy (P = 0.01). Patients with interstitial edema (P ˂ 0.001) or tubulitis (P = 0.005) had a better renal prognosis. CONCLUSION Renal biopsy is required to establish a definitive diagnosis of drug-induced AIN. Nevertheless, it is not carried out in a systematic way. The composition of cells in the interstitial infiltrate may at times be helpful in determining the etiology of AIN. In particular, the presence of a considerable proportion of eosinophils favors a diagnosis of drug-induced AIN. Moreover, during drug-induced AIN, histological data have a great prognostic value. In our study, the main histological prognostic factors were interstitial fibrosis, tubular atrophy, interstitial edema and tubulits. Further studies are needed to validate these results and establish a score based on histological data in order to predict renal outcome during drug-induced AIN.

Background and Aims Mesangial deposits Ig A was described the first time in 1968 by Berger and Hinglais. It remains the most common primary glomerulonephritis worldwide. It is often idiopathic but can also be secondary. The aim of our study is to describe the epidemiologic characteristics, the incidence and the anatomopathological features of 501 IgA nephropathy (IgA N) patients. Method It is a retrospective mono-centric study including patients having IgA N in the renal biopsy done in our department among a period of 17 years. Results We analyzed data of 8427 patients who underwent renal biopsy. 81% had glomerular nephropathy with 7.3% (501) IgA N. A male-to-female ratio of 2.27. The average age was 28.7 years. IgA N was primary in 80.2% cases and secondary in 17.8% cases. The most frequent secondary IgA N was rheumatoid purpura (74.8%). There was a male predominance in Berger‘s disease as well as in rheumatoid purpura. Berger’s disease was more common in adults, whereas rheumatoid purpura was more common in children. The main indication of renal biopsy was proteinuria with hematuria in 23.2% of cases and nephrotic syndrome in 23.8%. The association of non-nephrotic proteinuria, hematuria, arterial hypertension and renal injury was found in 9.3% whereas isolated macroscopic hematuria only in 6.4% of cases. According to HAAS classification, HAAS 3 was the most frequent. OXFORD classification used only from 2010, and M1, S1, E0, T0 and M1, S1, E0, T2 were the most frequent. Glomerular lesions were associated to tubulo interstitial and vascular lesions in 48.2% of cases. Conclusion IgA nephropathy is the most common glomerular disease and a frequent cause of end stage renal disease. Because of a clear increase of it’s incidence in our country and the delay in the diagnosis, a systematic screening of urines is needed in our country as it’s done in Singapore and Japan.

Background and Aims Anti-Glomerular basement membrane disease « anti-GBM » is a rare autoimmune disease. It most often results in a rapidly progressive glomerulonephritis syndrome associated with intra-alveolar hemorrhage. The diagnostic confirmation is histological, by the demonstration of linear deposits of immunoglobulins (IgG) along the glomerular basement membrane. The aim of our study was to describe its epidemiological, clinical, biological, immunological, histological, and evolutionary characteristics and to identify the different prognostic factors for predicting patient survival and renal survival. Method It was a retrospective, descriptive and analytical study including patients over 16 years old with anti-GBM disease proved by kidney biopsy and followed up over a period of 32 years (January 1985 to July 2017), in Internal Medicine Department of Charles Nicolle Hospital of Tunis. Results We collected 32 patients with a sex ratio H/F = 1.13. The mean age at diagnosis was 42 years old with extremes of 18 to 81 years old. The most frequent extra-renal manifestations were pulmonary (53%), neurological (12.5%) and ocular (6%) manifestations. Hematuria associated with proteinuria was constantly found. The latter was nephritic in 31% of patients. All patients had renal insufficiency on admission, oligo-anuric in 60% of cases. The use of extra-renal treatment at admission was necessary in 75% of patients. On the immunological level, the search for anti-MBG antibodies, performed in 20 patients, was positive in 65% of cases. All our patients had undergone a renal biopsy puncture with direct immunofluorescence study. Diffuse extra-capillary glomerulonephritis was observed in 93% of patients. Corticotherapy was initiated in 27 cases, associated with plasma exchange in 21 cases and cyclophosphamide in 17 cases. Nine of our patients died in the first year. Renal outcome was marked by partial remission in 2 cases and end-stage renal failure in 19 cases. In univariate analysis, an age greater than 60 years and the occurrence of respiratory distress were predictors of death. Oligo-anuria and need dialysis on admission were predictive factors for progression to end-stage renal failure. Conclusion Anti-GBM disease is a serious illness. Current therapeutic modalities have significantly improved patient survival. These must be intensive and rapid in order to hope for a favorable renal evolution whose prognosis remains reserved.

Background and Aims Hypertension is a common manifestation during systemic lupus erythematosus (SLE). Its mechanism is multifactorial and microthromboses of renal arterioles seem to be the most important mechanism. The objective of our study is to identify the histological and evolutionary characteristics of patients with lupus nephritis (LN) presenting with hypertension. Method A retrospective study of 85 patients followed for LES with lupus nephritis documented by a renal biopsy collected in 17 years and presenting with hypertension. Results Among 174 patients with LN, eighty-five (48.58%) are hypertensive. A sex ratio F / H of 6.08. The mean age of LN diagnosis was 36.4 years old [13 -75 years old]. The average time to onset of hypertension was 25.8 months [0-204 months]. Malignant hypertension was present in 12% of patients. Antiphospholipid Antibody Syndrome (APLS) was found in 35.3% of cases. Renal biopsy showed LN class II in 2 cases, class III in 8 cases, class IV in 43 cases, class V isolated in 8 cases and class VI in 3 cases. Vascular lesions were arteriolosclerosis in 40% of cases and thrombotic microangiopathy (TMA) lesions in 17.6% of cases. The treatment was essentially based on blockers of the renin angiotensin system, either as monotherapy or in combination with calcium channel blockers, beta blockers or central antihypertensives. The evolution was marked by the occurrence of cerebrovascular accidents associated in 7 cases with APLS and coronary artery disease in 2 cases. Renal evolution was marked by total and durable remission in 27.5%, chronic renal disease in 31.7%, and end-stage renal failure in 40.8% of cases. Blood pressure was balanced in 40,5 % of cases and unbalanced in 59,5% of cases. Conclusion In our lupus patients, hypertension was common, associated with severe glomerular and vascular lesions and a rather severe renal prognosis.

Background and Aims Systemic Lupus Erythematosus (SLE) is associated with an increased risk of cardiovascular morbidity and cardiovascular mortality. The risk of cardiovascular events is 1.3–2.7 times higher in SLE patients than in the general population, and even higher in patients with lupus nephritis (LN). Traditional risk factors as well as SLE-specific and treatment-related factors all contribute to the increased risk of cardiovascular disease. The primary aim of the present study was to evaluate cardiovascular risk factors, morbidity and mortality in patients with LN. Method This is a retrospective study of patients over the age of 16, with LN proved by kidney biopsy and followed up in our department over a period of 17 years. The diagnosis of lupus was made according to criteria of The American College of Rheumatology revised in 1997. Demographic, clinical and para-clinical data were collected from medical observations. Results We collected 155 women and 19 men with a sex ratio F / H of 8.2. The mean age at the time of the discovery of LN was 32.6 years [15-45 years]. Overall median follow-up time was 81.2 months. Renal symptomatology was dominated by proteinuria noted in all patients with an average proteinuria at 3.3 g / 24h, associated to a nephrotic syndrome in 68% of patients, hematuria was present in 69% of patients and renal failure was present in half of cases with an average serum creatinine of 110 µmol / l. At the time of diagnosis of LN, hypertension was noted in 48.9% of cases, diabetes in 2.8% of cases and obesity in 57.4% of cases with an index average body mass of 28.5 Kg / m2. Smoking was reported in 17.2% of the cases. The average cholesterol level was 5,5±2,1 mmol/l, the average triglycerid level was 2,5±1,1 mmol/. Antiphospholipid syndrome was found in 14.9% of cases. We performed 243 renal biopsies with 174 initial and 69 iterative biopsies. The histological lesions were polymorphic dominated by LN class IV (54.3%), arteriolosclerosis was observed in 47.7% and lesions of thrombotic microangiopathy in 29.8%. Corticosteroid therapy was prescribed in all patients combined with immunosuppressive therapy in 54.6% of cases. The overall survival of the patients at 10 years was 85%. During follow-up, cardiovascular complications found in our series were mainly strokes (6.3%) and coronary insufficiency (5.2%) and transient ischemic attack (6.9%). After a univariate analysis, the additional cardiovascular risk factors identified in our study were antiphospholipid syndrome (p = 0.01), renal failure (p = 0.01), long-term corticosteroid therapy (p = 0.009), the chronicity of the disease (evolution of lupus> 10 years) (p = 0.014), proliferative forms (p=0.001), arteriolosclerosis (p=0.0002) and lesions of thrombotic microangiopathy (p=0.018). Survival in patients without cardiovascular risk factors was better (96% vs 88%). Conclusion In conclusion, in addition to traditional risk factors SLE patients have several disease related risk factors that explain increase cardiovascular disease. A careful control for this risk factors is essential to continuously improve survival in SLE.

Background and Aims Crystal-induced kidney disease refers to kidney injury caused by intratubular crystal deposition. The most common forms of crystalline nephropathy encountered in renal pathology are nephrocalcinosis and oxalate nephropathy. The purpose of our study is to determine the epidemiological and clinical characteristics of hyperoxaluria diagnosed from renal biopsy. Method We retrospectively reviewed all kidney biopsy specimens evaluated at renal pathology laboratory, from 1976 to 2019. The biopsy specimens were received from multiple medical department and medical centers. We studied 8900 biopsy specimens and we were focused on patients whose diagnosis of hyperoxaluria was made from renal biopsy Results We identified 25 cases (15 children and 10 adults) with a sex ratio H / F of 0.9. Mean age at diagnosis was 17.2 years old [4 months-73 years old]. Most patients were offspring of consanguineous mating (14 of 25) with intermarriage of first-degree cousins being the most common pattern. A family history of chronic kidney disease was found in 13 patients: indeterminated nephropathy (n = 6) and renal stone (n = 5) and primary hyperoxaluria (n=2). Among our patients, five had a history of urolithiasis. One patient had a history of chronic diarrhea related to Crohn's disease and one patient had a history of cephalic pancreatectomy and ileal resection. Initial symptoms and signs were dominated by renal failure (n = 25) with mean creatinine of 789.5 μmol / l [306-1832μmol / l], associated with proteinuria in 10 patients and hematuria in 11 patients. Arterial hypertension was present in 4 patients. Oligo anuria was reported in 4 patients without dilation of the urinary excretory pathways. In our patients, the diagnosis of crystalin nephropathy was revealed by renal biopsy. In one case, the diagnosis was made after renal transplant. In 4 cases the diagnosis was made by postmortem kidney biopsy. In all cases, the kidney biopsy specimen showed extensive intratubular crystal deposition and tubulointerstitial mononuclear cell infiltration with features of tubular injury and interstitial fibrosis. Examination of histologic slides showed colorless refractile crystals of polygonal appearance. Multicolored birefringence under polarized light identified these crystals as calcium oxalate. After different investigations (genetic and biological analysis), the diagnosis of hyperoxaluria was confirmed. Hyperoxaluria was primary in 23 patients and secondary in 2 patients. Conclusion Hyperoxaluria is a rare condition, often serious, involving renal prognosis and sometimes life-threatening, especially in early-onset forms. Early diagnosis and treatment should be done as soon as possible to slow the progression to end-stage renal failure. In patients with renal insufficiency, the diagnosis of hyperoxaluria is difficult. Renal biopsy can help when clinical and radiological data are not sufficient.