Granulomatous Interstitial Nephritis Research Articles

#68 Novel clinical application of urinary angiotensin-converting enzyme assay in renal sarcoidosis: a retrospective observational study

Abstract Background and Aims Renal manifestations of sarcoidosis are observed in approximately 1–5% and characterized mainly by granulomatous interstitial nephritis, which could lead to kidney failure. Angiotensin-converting enzyme (ACE) reflects the presence of granuloma; hence, serum ACE and tubular injury markers are measured in renal sarcoidosis (RS); however, they either have low sensitivity or low specificity. Although its practicality has not been established, the use of ACE levels in cerebrospinal fluid has been reported for neuro-sarcoidosis. Therefore, we hypothesized that urinary ACE could reflect granuloma presence in the kidneys and could be a disease-specific marker for RS. Method This was a single-center, retrospective observational study. We evaluated clinical characteristics and kidney biopsy findings from electronic medical record surveys and kidney biopsy specimens. The control groups included sarcoidosis without renal involvement (SAR-control) and tubulointerstitial nephritis without a sarcoidosis etiology (TIN-control). Serum and urinary ACE levels were measured, and urinary fractional excretion of ACE (FEACE) was investigated. Serum ACE assay and urinary ACE levels were measured using the colorimetric method with p-hydroxybenzoyl-glycyl-L-histidyl-L-leucine. A total of six patients (three with RS; one with sarcoidosis as controls; and two with TIN controls) with undetectable urinary ACE levels were excluded from the urinary ACE and FEACE analyses. Tubulointerstitial lesions were visually assessed for essentially normal (%), inflammatory cell infiltrates (%), tubular atrophy (%), and interstitial fibrosis (%) by several board-certified nephrologists, and analyzed the correlation of these lesions with each marker. Results This study included 18 patients with RS, 18 as SAR-control, and 10 as TIN-control. Serum ACE, urinary ACE, and FEACE levels in the RS group were significantly higher than those in the control groups. Receiver operating characteristic analysis identified FEACE and serum ACE levels as useful biomarkers for diagnosing RS among patients with both controls, respectively. In the RS group, FEACE was positively correlated with the degree of tubulointerstitial injury (r = 0.69, P = 0.0045), and the cutoff value of FEACE for diffuse tubulointerstitial injury (50.0% or more) was 0.39%, with a sensitivity and specificity of 100.0%. Furthermore, obvious positive correlations were observed among FEACE, inflammatory cell infiltrates (r = 0.53, P = 0.044), and interstitial fibrosis (r = 0.56, P = 0.029) in the RS group but not in the TIN-control. Conclusion Combination with serum and urinary ACE could help diagnose and assess disease severity among patients with RS.

40 A case report description of a patient with CVID and Granulomatous Interstitial Nephritis

40 A case report description of a patient with CVID and Granulomatous Interstitial Nephritis

Kidney manifestations of sarcoidosis

Renal involvement is a clinically relevant organ manifestation of sarcoidosis, leading to increased morbidity and complications. Although the exact incidence remains unknown, renal disease is likely to occur in up to one third of all sarcoidosis patients. Every patient with newly diagnosed sarcoidosis should receive a renal work-up and screening for disrupted calcium metabolism.Amid various forms of glomerulonephritis, granulomatous interstitial nephritis is the most common one, but it rarely leads to renal impairment. Histologically, granulomas can be absent. Nephrocalcinosis and nephrolithiasis are frequent forms when hypercalcaemia or hypercalciuria occur. Drugs used for treatment of systemic sarcoidosis can also cause renal damage.Due to its high heterogeneity, renal sarcoidosis can be difficult to treat. Glucocorticoids and various immunosuppressive treatments have been proven to be effective based on case series, but clinical trials are lacking. A treatment guideline for renal sarcoidosis is urgently needed.In this review article, we present an overview of the different forms of renal sarcoidosis and the diagnostic steps to confirm renal involvement; in addition, we provide insights on the management and available treatments. A better understanding regarding the pathogenesis of sarcoidosis is the key for the development of more specific, targeted therapies.

Granulomatous Acute Interstitial Nephritis Revealing Multisystem Sarcoidosis Associated with Thyroiditis and Cushingoid Syndrome: Report of a Case and Review of the Literature

Introduction: Sarcoidosis can present with acute renal failure (ARF) due to granulomatous interstitial nephritis (GIN). We report the case of granulomatous acute renal failure (ARF) revealing multisystemic sarcoidosis in the nephrology department of the Aristide Le Dantec hospital in Dakar. Observation: Mrs. kD aged 54 with a past history of high blood pressure for 22 years, a multi nodular euthyroid goiter, referred to the nephrology department for impaired renal function. The clinical examination revealed at entry, deterioration in the general condition with weight loss and non-selective anorexia. Clinical anemia was also noted. The clinical examination also revealed Cushingoid syndrome and dry mouth syndrome. On biology, the blood count showed bicytopenia with anemia at 10.9 g/dl and leukopenia at 2620/mm3. There was an impairment of renal function with creatinine at 139.2 mg/l and blood urea at 1.76 g/l. The renal ultrasound became normal. Cervical ultrasound showed an aspect of abscessed thyroiditis of the right lobe. Chest computed tomography (CT) showed bilateral hilar adenomegaly and a band of bilateral basal linear atelectasis. The renal biopsy showed glomeruli of subnormal structure, the interstitium is riddled with tuberculoid follicles formed of epithelioid and multinucleated histiocytes of the Langhans type. The diagnosis of granulomatous acute interstitial nephritis revealing multisystemic sarcoidosis was kept. The evolution was favorable after 1 month of treatment with corticosteroid therapy with a clear improvement in renal function. Conclusion: Renal manifestations during sarcoidosis are rare. They can be indicative of the disease as in our patient. Renal biopsy is essential in any patient presenting with impaired renal function with extra-renal signs.

De novo normotensive scleroderma renal crisis six years after living-donor renal transplantation in a patient with overlapping systemic sclerosis/systemic lupus erythematosus syndrome: a case report

BackgroundScleroderma renal crisis (SRC) is a critical kidney involvement of systemic sclerosis (SSc), often resulting in end-stage renal disease. Although the recurrence of SRC in the allograft has been reported, the development of de novo SRC after kidney transplantation has not been reported. Furthermore, normotensive SRC, which rarely occurs, makes prompt diagnosis more challenging. This fact should be recognized widely among nephrologists.Case presentationWe report a 37-year-old Japanese man with overlapping SSc/systemic lupus erythematous syndrome who developed normotensive SRC in the transplanted kidney shortly after glucocorticoid escalation. Six years prior to admission, he underwent an ABO-compatible living donor kidney transplantation because of lupus nephritis. He was admitted to our hospital for gradually worsening kidney dysfunction. A kidney biopsy showed idiopathic granulomatous interstitial nephritis and high-dose prednisolone was prescribed. Although renal function improved tentatively, it deteriorated again a week later. A secondary kidney biopsy revealed acute thrombotic microangiopathy, leading to the diagnosis of normotensive SRC because all other causes were excluded, and blood pressure was within normal range. Adding an angiotensin-converting enzyme inhibitor and tapering glucocorticoid slowed the speed of deterioration of his kidney function, but he finally required hemodialysis induction.ConclusionsSRC can newly develop even in the transplanted kidney, especially when high-dose glucocorticoid is administered. Normotensive SRC makes the diagnosis challenging, so nephrologists should carefully monitor patients with SSc and transplanted kidneys to treat SRC promptly.

Interferon-gamma Release Assay-positive Granulomatous Interstitial Nephritis in a Patient with a History of Diffuse Large B Cell Lymphoma.

Tuberculosis is a common etiology of granulomatous interstitial nephritis (GIN). However, the absence of evidence of lung involvement and lack of mycobacterial isolation in cultures make the etiological diagnosis and treatment decision challenging. We herein report a 46-year-old man with severe renal failure, a persistent fever, and a history of lymphoma. A renal biopsy exhibited GIN. Despite no evidence of tuberculosis except for a positive interferon-gamma release assay (IGRA), the patient was successfully treated with anti-tuberculosis drugs. Our case suggests that anti-tuberculosis therapy should be considered for patients with IGRA-positive GIN after excluding other etiologies.

Clinicopathological Characteristics and Outcomes of Renal Sarcoidosis: A Series Study of 18 Patients from a Single Center

Introduction: Sarcoidosis is characterized by noncaseating granulomatous inflammation in multiple organs. Renal involvement is rare, and granulomatous interstitial nephritis (GIN) is the predominant histological feature. Renal sarcoidosis (RS) is usually diagnosed by exclusion, combining clinical and histological findings, and often remains misdiagnosed. This retrospective study aimed to describe the characteristics and prognosis of patients with RS in China. Methods: Eighteen patients with RS from a single center were enrolled, of whom 15 had biopsy-proven tubulointerstitial nephritis. Their clinicopathological features and renal outcomes were analyzed to understand this rare disease better. Results: Eighteen patients (14 male/4 female) were included in our study. The median estimated glomerular filtration rate (eGFR) was 30.36 (11.57, 60.14) mL/min/1.73 m². In 15 patients undergoing a renal biopsy, GIN was the most common pathological phenotype (66.67%). Seventeen patients had follow-up records, with a median follow-up of 24.07 (8.82, 60.90) months. One month after treatment, median eGFR increased significantly from 30.36 (11.57, 60.14) mL/min/1.73 m² to 58.53 (39.35, 80.65) mL/min/1.73 m², and proteinuria decreased from 1.10 (0.69, 1.58) g/24 h to 0.68 (0.52, 1.05) g/24 h. No patients relapsed or developed end-stage renal disease. Conclusion: RS is a rare but important cause of tubulointerstitial injury, with a favorable long-term prognosis if properly diagnosed and treated promptly.

The Evolving Spectrum of Kidney Histology in HIV-Positive Patients in South Africa

Sub-Saharan Africa remains challenged by the highest burden of human immunodeficiency virus (HIV), an epidemic of tuberculosis (TB), and increasing number of people with HIV (PWH) on antiretroviral therapy (ART), all of which may result in kidney injury. This observational cohort study describes the spectrum of kidney disease in PWH in South Africa, between 2005 and 2020. Kidney biopsies were analyzed in 4 time periods as follows: early ART rollout (2005-2009), tenofovir disoproxil (TDF) introduction (2010-2012), TDF-based fixed dose combination (2013-2015), and ART at HIV diagnosis (2016-2020). Logistic regression was used to identify factors associated with HIV-associated nephropathy or focal segmental glomerulosclerosis (HIVAN/FSGS) and tubulointerstitial disease (TID). We included 671 participants (median age 36, interquartile range, 21-44 years; 49% female; median CD4 cell count 162 [interquartile range, 63-345] cells/mm3). Over time, ART (31%-65%, P< 0.001), rate of HIV suppression (20%-43%, P< 0.001), nonelective biopsies (53%-72%, P< 0.001), and creatinine at biopsy (242-449 μmol/l, P< 0.001) increased. A decrease in HIVAN (45%-29% P< 0.001) was accompanied by an increase in TID (13%-33%, P< 0.001). Granulomatous interstitial nephritis accounted for 48% of TID, mostly because of TB. Exposure to TDF was strongly associated with TID (adjusted odds ratio 2.99, 95% confidence interval 1.89-4.73 P< 0.001). As ART programs intensified and increasingly used TDF, the spectrum of kidney histology in PWH evolved from a predominance of HIVAN in the early ART era to TID in recent times. The increase in TID is likely due to multiple exposures that include TB, sepsis, and TDF as well as other insults.

Case of Granulomatous Interstitial Nephritis with Mediastinal Lymphadenopathy

Granulomatous interstitial nephritis (GIN) is a rare diagnosis on kidney biopsy. It is generally diagnosed on kidney biopsy in patients with renal dysfunction with no significant proteinuria. The etiology of GIN is multifactorial. A high index of suspicion for tuberculosis should be kept in all patients with GIN.

Renal replacement therapy in sarcoidosis.

Sarcoidosis is a systemic inflammatory disease of unknown etiology. Kidney involvement in sarcoidosis may be present in up 25-30% of cases. An early diagnosis and prompt treatment with corticosteroids can improve the prognosis but rarely renal sarcoidosis can lead to kidney failure needing renal replacement therapy (RRT). Acute kidney injury (AKI) in sarcoidosis may be caused by granulomatous interstitial nephritis (GIN) or hypercalcemia. These disorders are usually clinically silent and may lead end stage renal disease (ESKD) if not diagnosed or detected too late. In patients with ESKD, dialysis and renal transplantation can offer results comparable to those observed in patients with other causes of kidney failure. Based on a review of literature, we present an overview of RRT in patients with AKI or chronic kidney disease (CKD) caused by sarcoidosis.

Difficulties in the differential diagnosis of granulomatous interstitial nephritis

Difficulties in the differential diagnosis of granulomatous interstitial nephritis

Renal Sarcoidosis Presenting as Fanconi Syndrome

Fanconi syndrome is an extremely rare complication of renal sarcoidosis. We describe a case of biopsy-proven granulomatous interstitial nephritis secondary to sarcoidosis with the rare presenting feature of Fanconi syndrome. Our patient successfully received steroids initially, followed by mycophenolate and infliximab. These findings provide clinicians an important insight in recognizing this rare complication of sarcoidosis and opportunity to consider alternative regimens that can avoid or reduce side effects of first-line steroid therapy.

Renal Limited Sarcoidosis Presenting as Granulomatous Interstitial Nephritis

Renal Limited Sarcoidosis Presenting as Granulomatous Interstitial Nephritis

The pathological and outcome characteristics of renal lesions in Crohn’s disease

BackgroundThe inflammatory bowel disease, containing Crohn’s disease and ulcerative colitis, was rare in the population, especially in the complication of kidney disease. A few studies had found proteinuria played a potential indicator of inflammatory bowel disease occurrence and activity. This study aimed to better define the histopathologic spectrum and study the outcome of renal disease in Crohn’s disease.MethodsA retrospective study of 3557 Crohn's disease from January 1st, 2016 to July 1st, 2021 in the Sixth Affiliated Hospital of Sun Yat-sen University identified 20 (0.56% [20/3557]) patients who underwent kidney biopsy. All biopsy specimens were examined by standard procedures containing light microscopy, immunofluorescence, and electron microscopy.ResultsTwenty cases were shown in this review study. Subnephrotic proteinuria (30% [6 of 20]), persistent hematuria and proteinuria (25% [5 of 20]), and isolated hematuria with acanthocytes (25% [5 of 20]) were the main indications for kidney biopsy. The most common diagnosis was IgA nephropathy (70% [14/20]), followed by minimal change disease (10% [2/20]), acute interstitial nephritis (5% [1/20]), granulomatous interstitial nephritis (5% [1/20]), non-IgA mesangial proliferative nephritis (5% [1/20]) and thin basement membrane nephropathy (5% [1/20]). The Lee classification of IgA nephropathy was mostly II or III level. Glomerular mesangial hyperplasia was the most common pathologic manifestation according to the MEST-C Sore. After twelve-month treatment, the majority of patients turned to complete remission of renal disease by measuring proteinuria, while 3 patients still stayed in the relapse stage and 6 patients turned to partial remission by measuring hematuria.ConclusionsIgA nephropathy is the most common kidney biopsy diagnosis in Crohn's disease. Renal damage in Crohn's disease mainly involves the glomerulus, especially the mesangial matrix. After the treatment, proteinuria might be in remission, but hematuria remains.

Renal sarcoidosis.

Sarcoidosis is a systemic inflammatory disease of unknown etiology. The pathogenesis rests on an aberrant T cell response to unidentified antigens in individuals predisposed by genetic and environmental factors. Increased expression of polarized macrophages and disequilibrium between effector and regulator T cells contribute to the formation of noncaseating granulomas, that are frequently found in affected organs. The main kidney abnormalities in sarcoidosis are granulomatous interstitial nephritis (GIN) and hypercalcemia-related disorders. The clinical diagnosis is difficult. The outcome is variable, ranging from spontaneous remission to end-stage kidney disease (ESKD). Early diagnosis and prompt treatment with corticosteroids can improve the prognosis. Hypercalcemia may be responsible for acute kidney injury (AKI) caused by vasoconstriction of afferent arterioles. Complications of persistent hypercalcemia include nephrocalcinosis and renal stones. In patients with ESKD, dialysis and transplantation can offer results comparable to those observed in patients with other causes of kidney failure. Based on a review of the literature, we present an overview of the etiopathogenesis, the renal manifestations of sarcoidosis and their complications, management and prognosis.

Hypercalciuria may predict better response to immunosuppressive therapyin renal sarcoidosis: a case series.

Renal sarcoidosis is a rare cause of tubulointerstitial nephritits(TIN). The clinical and pathological characteristics, as well as outcomes, of renal sarcoidosis remain unclear. This single-center study retrospectively analyzed 18 patients affected bysarcoidosis with tubulointerstitial nephritis (TIN) and 53 patients with tubulointerstitial nephritisnot related to sarcoidosis.Patientswere further stratified into the granulomatous (12 sarcoidosis and 6 non-sarcoidosis) and non-granulomatous (6 sarcoidosis and 47 non-sarcoidosis) TIN groups. Half of the patients with renal sarcoidosis had signs ofacute kidneyinjury at kidneybiopsy, 94% of whom presented with extra-renal involvement. The prevalence of hypercalcemia, hypercalciuria, and elevated serum angiotensin-converting enzyme levels was 27.6%, 33.3%, and 31.3%, respectively. Renal sarcoidosis patients with eGFR < 30mL/min/1.73 m2 scored higher for total chronic tubulointerstitial injury (p = 0.044) and glomerular sclerosis (p = 0.027). Compared to non-sarcoidosispatients, higher urinary calcium levels (for patients with GFR [Formula: see text] 40mL/min/1.73 m2, p = 0.034), lower scores of acute tubular injury (p = 0.008), and more prominent glomerular sclerosis were observed in renal sarcoidosis. Similar characteristics of chronicity and hypercalciuria were also identified in granulomatous interstitial nephritis; however, interstitial inflammation was obvious (p = 0.001). Patients with renal sarcoidosis were initially treated with corticosteroids. Five patients receiving immunosuppressive agents showed better long-term renal recovery. High 24-h urine calcium (adjusted by weight) was identified as a factor associated with long-term remission. Renal sarcoidosis is a systemic disease of insidious onset and chronic progression, sharing similar features of chronicity and hypercalciuria with granulomatous interstitial nephritisof other cause. Hypercalciuria may predict a better response toimmunosuppressive therapy, presumablyindicating active interstitial inflammation; thus, strengthened immunosuppression might be considered.

MULTISYSTEMIC SARCOIDOSIS: AN UNUSUAL PRESENTATION

TYPE: Case Report TOPIC: Pulmonary Manifestations of Systemic Disease INTRODUCTION: Sarcoidosis is a chronic multisystemic disease characterized by noncaseating granulomas which affects the pulmonary system and intrathoracic lymph nodes most frequently. Pleural and renal involvement in sarcoidosis is rare. CASE PRESENTATION: A 34 year old African American female with presented with progressively worsening shortness of breath. Of note, this was her fourth hospitalization in six months. Her first presentation was for flank pain. Workup revealed a renal infiltrative process and a left sided pleural effusion. Kidney biopsy was significant for noncaseating granulomas. A right lower lobe pulmonary embolus (PE) was diagnosed on her second admission and recurrent left sided pleural effusions were noted on the third and fourth admissions. Hepatic infiltrative hypodensities in the liver were visualized. Angiotensin converting enzyme level was 137 U/L. On her final presentation, bronchoscopy demonstrated a stereotypical cobblestone appearance and transbronchial lymph node biopsy demonstrated non-necrotizing granulomatous disease. DISCUSSION: Most cases of sarcoidosis tend to affect the lungs, however, both pleural effusion or granulomatous interstitial nephritis (GIN) as a presenting symptom of the disease is uncommon. Pleural involvement is sarcoidosis occurs in 0.7-10%. Clinically relevant GIN is identified in 0.5-0.9% of native kidney biopsies making it a rare histological diagnosis. With workup for other pathology being negative, sarcoidosis was assessed as the cause for the unique clinical course of this patient with biopsy proven pleural and renal disease, and possible hematologic, ocular, and hepatic involvement. CONCLUSIONS: Clinicians must maintain a high level of suspicion for sarcoidosis in patients with multisystemic disease, due to the potential for atypical presentations. DISCLOSURE: Nothing to declare. KEYWORD: Sarcoidosis

MO137: Sarcoidosis in a Living Kidney Donor Candidate: Case Report and Review of the Literature

Abstract BACKGROUND AND AIMS Sarcoidosis (SCD) is a granulomatous disease that mostly affects young adults, presenting with hilar adenopathy, lung reticular opacities and skin/joint/eye lesions. Incidence varies in Europe between 0.3% and 1.5%, higher in southern countries. Up to one-third of patients have extrathoracic manifestations. Renal involvement varies among different case series. Despite a prevalence of about 13% in autopsies on systemic SCD affected individuals, it is clinically evident in 0.7–4.3% of patients, with a reduced glomerular filtration rate associated with mild or absent urinary anomalies. It usually presents as a tubulointerstitial nephritis at kidney biopsy. Noncaseating granulomas are typical but not always present. Renal injury can also derive from hyperkalcaemia and hypercalciuria (secondary to vitaminD production in granulomas), which cause nephrocalcinosis or nephrolitiasis. A clinical presentation with hyperkalcaemia associates to a better response to therapy (prednisone 1 mg/kg/day for 6–12 weeks, tapered in 6–9 months). An Italian survey on SCD acute kidney injury (AKI) described female sex, hyperkalaemia and absence of granulomas at biopsy as positive prognostic factors, without any correlation between proteinuria and histological damage. SCD AKI evolved to CKD in over 60% of cases (37.5% without comorbidities at onset), with a mean GFR slope of 5 mL/min/year when granulomatous interstitial nephritis was present. METHOD We describe the case of a 55-year-old male, who proposed as a living kidney donor for his wife. His clinical history included a paranoid episode 20 years before, compensated and on psychiatric follow-up at the moment of the screening, dyslipidaemia and normal blood pressure. RESULTS Preoperative screening showed a renal function just above safety threshold for donation (cystatin C-creatinine CKD-EPI 80 mL/min/1.73 m2), a normal urinary sediment and no proteinuria. A thoracic and abdominal CT scan (Figure 1) described numerous aorto-caval adenopathies, stable at a second CT after 3 months. Lungs were unaffected, kidneys and the urinary tract were regular, without calcifications or stones. No infection was detected (negative QuantiFERON, HIV, EBV &amp;lt;1000 copies/mL), suggesting a differential diagnosis between lymphoma and SCD. Serum and urine electrophoresis, immunofixation, light chains, Bence Jones and peripheral blood lymphocyte typing were checked in parallel to ACE dosing; 24-h urine calcium, calcemia, vitamin D, dermatological and ocular examination all normal. An endobronchial ultrasound biopsy was performed, after a PET (Figure 2) to identify the targets with the highest SUV (3.9–6.7). Histology described normal lymphocytes, noncaseating granulomas with sarcoidosis epithelioid histiocytes. CONCLUSION Stage 1 pulmonary SCD without clinical renal involvement was confirmed. Although in a single case of living kidney donation from SCD affected subject was reported, data on GFR deterioration in the long term are lacking. Considering the baseline renal function of the potential donor and the not-quantifiable risk of future AKI, we decided to deem him unfit for donation, despite the absence of markers of disease activity at the moment of the screening. Kidney biopsy will be considered in the future in case of urinary abnormalities or GFR deterioration.

Hematological Malignancies and the Kidney.

The incidence of hematologic malignancies is on the rise worldwide. Kidney disease is ubiquitous in patients with hematologic malignancies, encompassing a wide spectrum of disorders involving each kidney compartment, including the vasculature, tubules, interstitium, and glomerulus, and there is significant overlap of kidney involvement with each hematologic malignancy. Vascular disorders include both microvascular and macrovascular damage, via thrombotic microangiopathy, hyperleukocytosis, hyperviscosity, and cryoglobulinemia. The tubulointerstitial compartment may be affected by prerenal azotemia and acute tubular injury, but malignant infiltration, tumor lysis syndrome, extramedullary hematopoiesis, cast nephropathy, granulomatous interstitial nephritis, and lysozymuria should be considered in certain populations. Obstructive uropathy may occur due to nephrolithiasis or retroperitoneal fibrosis. Glomerular disorders, including membranoproliferative, membranous, minimal change, and focal segmental glomerulosclerosis, can rarely occur. By understanding how each compartment may be affected, care can best be optimized for these patients. In this review, we summarize the widely varied etiologies of kidney diseases stratified by kidney compartment and hematologic malignancy, focusing on demographics, pathology, pathophysiology, mechanism, and outcomes. We conclude with common electrolyte abnormalities associated with hematologic malignancies.

Spectrum of Biopsy Proven Primary Tubulointerstitial Diseases of the Kidney: A Single Centre Study

Background: The tubulointerstitial diseases can be due to a wide variety of etologies and mechanisms which vary with age, race and geographical area. In this study we aim to study the clinicopathological spectrum of biopsy proven primary tubulointerstitial diseases among patients in North India.&#x0D; Methods: This is a 5 year retrospective, single centre cohort, observational study.The data base was searched to identify all patients with primary tubulointerstitial diseases in their native kidney biopsies.&#x0D; Results: A total of 3091 renal biopsies were studied of which 283 were primary tubulointerstitial diseases. The mean age of patients was 43.2 (±14.6) years. Most of the patients were males with acute kidney injury as the most common presentation. Tubulointerstitial nephritis was the most common disease occurring in 126 patients. Acute interstitial nephritis was seen in 81 patients and chronic interstitial nephritis was seen in 45 patients. Granulomatous interstitial nephritis was seen in 27 patients. There were four patients of pigment nephropathy, 83 cases of acute tubular necrosis and 19 cases of cast nephropathy.&#x0D; Conclusion: Primary tubulointerstitial diseases comprise about 9.1% of the total cases. Tubulointerstitial nephritis is the most common diagnosis in these patients. Tuberculosis is still a leading cause of granulomatous interstitial nephritis in our country followed by fungal etiology. Acute cortical necrosis affects mostly females post obstretric complications in our setup. Given the enemic nature of malaria in India, G-6PD deficiency is an important differential in patients presenting with pigment nephropathy.&#x0D; Keywords: Biopsy, Tubulointerstitial Diseases of the Kidney, Tuberculosis, Acute cortical necrosis