The protean face of renal sarcoidosis

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.

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.

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.

Efficacy and safety of methylprednisolone pulse followed by oral prednisone versus oral prednisone alone in sarcoidosis tubulointerstitial nephritis. A randomized, open-label, controlled clinical trial

OBJECTIVE

To determine the benefit of pulsed methylprednisolone for improving renal function in sarcoidosis tubulointerstitial nephritis (TIN).

PATIENTS AND METHODS

A multicenter, prospective, randomized, open-labeled, controlled trial in patients with biopsy-proven acute TIN due to sarcoidosis was conducted in 21 sites in France. Patients were randomly assigned to receive a methylprednisolone pulse 15 mg/kg/day for 3 days then oral prednisone (MP group) or oral prednisone 1 mg/kg/day alone (PRD group). The primary endpoint was a positive response at 3 months, defined as a doubling of eGFR as compared with before randomization.

RESULTS

We randomized 40 participants. Baseline eGFR before PRD was 22 ml/min/1.73m2 (interquartile range [IQR] 16-44) and before MP was 25 ml/min/1.73m2 (IQR 22-36) (P = 0.3). The two groups did not differ in underlying pathological lesions, including mean percentage of interstitial fibrosis and intensity of interstitial infiltrate. In the intent-to-treat population, the median eGFR at 3 months did not significantly differ between the PRD and MP groups: 45 (IQR 34-74) and 46 (IQR 39-65) ml/min/1.73m2. The primary endpoint at 3 months was achieved in 16/20 (80%) PRD patients and 10/20 (50%) MP patients (P = 0.0467). eGFR was similar between the two groups after 1, 3, 6, and 12 months of treatment. For both groups, eGFR at 1 month was highly correlated with eGFR at 12 months (P < 0.0001). The two groups did not differ in severe adverse events.

CONCLUSION

As compared with a standard oral-steroid regimen, intravenous MP may have no supplemental benefit for renal function in patients with TIN due to sarcoidosis. ClinicalTrials.gov: NCT01652417; EudraCT: 2012-000149-11.

Acute interstitial nephritis after COVID-19 vaccination

A woman in her 70s presented to the hospital being generally unwell 8 days following the first dose of the AstraZeneca COVID-19 vaccination. She was in stage III acute kidney injury (AKI) with hyperkalaemia and metabolic acidosis. Urinalysis showed haematoproteinuria. Renal immunology screen was negative. She subsequently underwent two renal biopsies. The second biopsy showed features consistent with acute tubulointerstitial nephritis. She was commenced on oral steroids, which led to marked improvement of her renal function.There are reasons why AKI can occur post vaccination such as prerenal AKI from reduced oral intake postvaccination due to feeling unwell or developing vomiting or diarrhoea. Intravenous fluids were given to this patient but with no meaningful improvement in renal function. She developed a possible reaction to the AstraZeneca COVID-19 vaccine, which led to AKI as supported by the interstitial inflammation and presence of eosinophils on renal biopsy.

Clinical Features, Histopathology and Differential Diagnosis of Sarcoidosis

Sarcoidosis is a chameleon disease of unknown etiology, characterized by the growth of non-necrotizing and non-caseating granulomas and manifesting with clinical pictures that vary on the basis of the organs that are mainly affected. Lungs and intrathoracic lymph nodes are the sites that are most often involved, but virtually no organ is spared from this disease. Histopathology is distinctive but not pathognomonic, since the findings can be found also in other granulomatous disorders. The knowledge of these findings is important because it could be helpful to differentiate sarcoidosis from the other granulomatous-related diseases. This review aims at illustrating the main clinical and histopathological findings that could help clinicians in their routine clinical practice.

Co-Existence of Sarcoidosis and Sjögren's Syndrome with Hypercalcemia and Renal Involvement: A Case Report and Literature Review

BACKGROUND

Sarcoidosis and Sjögren's syndrome (SS) are chronic multi-system inflammatory diseases of unknown origin that most commonly attack the salivary glands. Both of the diseases have vague and non-specific symptoms, causing difficulties for the clinicians to distinguish between the two diseases. Main diagnostic criteria of SS exclude sarcoidosis. However, a co-existence of both diseases should be noted. Here, a case of co-existing sarcoidosis and Sjögren's syndrome is reported, complicated with severe hypercalcemia and renal failure, in addition to a literature review.

CASE PRESENTATION

A 71-year-old man visited our hospital complaining of daily progressive oral dryness, thirst, and blurred vision with a feeling of dry eyes for a one-year duration. His physical examination showed enlargement of both sides of cervical and supraclavicular lymph nodes. Lung auscultation showed decreased breath sounds with bibasilar inspiratory crackles. However, initial laboratory results revealed severe hypercalcemia with moderate hypercalciuria and renal failure. The final diagnosis was co-existing SS and sarcoidosis according to clinical, radiological, and laboratory data. The patient received oral prednisone therapy for 18 months. After a follow-up of years, the serum calcium concentration, renal function, and chest CT scan remained normal after prednisone treatment stopped for more than 18 months.

CONCLUSION

In the literature, calcium metabolic disorder and renal involvement have not been reported among patients with Sarcoidosis and Sjögren's syndrome, suggesting that calcium metabolic disorder may be underestimated. Serum and urine calcium concentration should be measured in addition to routine laboratory tests.

Systemic Sarcoidosis Presenting with Renal Involvement Caused by Various Sarcoidosis-associated Pathophysiological Conditions

A 61-year-old man was diagnosed with sarcoidosis involving the lungs, eyes, parotid gland and extrathoracic lymph nodes complicated by chronic kidney injury and hypercalcemia. Kidney biopsy showed non-specific interstitial nephritis and nephrosclerosis. However, immunohistochemical staining of cell surface markers revealed a multinucleated giant macrophage surrounded by T-cells, suggesting granulomatous interstitial nephritis. Corticosteroid improved the kidney function, and reduced the serum levels of calcium and angiotensin-converting enzyme. Sarcoid nephropathy may be caused by the combination of several sarcoidosis-associated pathophysiological conditions and a comprehensive kidney examination should be performed to assess the type of injury when determining a treatment strategy.

Renal sarcoidosis: a rare case

Sarcoidosis is a multisystemic granulomatous disease with rare renal involvement. We describe a case of a 45-year-old female patient admitted to the hospital with severe acute kidney injury and uveitis. After clinical investigation, sarcoidosis with renal, hepatic and ocular involvement was diagnosed. Renal biopsy revealed acute granulomatous interstitial nephritis and treatment with systemic corticosteroids was started with marked improvement in renal function.

Tubulointerstitial nephritis and uveitis

PURPOSE OF REVIEW

Tubulointerstitial nephritis and uveitis (TINU) is an important yet underrecognized ocular inflammatory syndrome. This review summarizes key historical publications that identified and defined the syndrome, and more recent literature that reveal the importance of urinary β2-microglobulin testing and kidney biopsy in the diagnostic evaluation of patients with TINU. Additionally, research studies providing new insights into disease pathogenesis are highlighted.

RECENT FINDINGS

In contrast with initial reports of TINU manifesting exclusively as an anterior uveitis in pediatric patients, more recent reports have identified TINU in patients of all ages with a wide range of ocular manifestations. Urinary β2-microglobulin has emerged as a sensitive and specific laboratory screening test, and the role of kidney biopsy in differentiating TINU from sarcoidosis continues to evolve. Genetic studies have identified HLA-DQA101, HLA-DQB105, and HLA-DRB101 as high-risk alleles and the identification of antimonomeric C-reactive protein antibodies suggests a role for humoral immunity in disease pathogenesis. Management strategies have evolved to include systemic anti-inflammatory treatment as a result of important outcome studies in patients with significant renal and ocular disease.

SUMMARY

With greater recognition, understanding, and treatment of this syndrome, both ocular inflammation and renal disease can be better addressed.

Management of extrapulmonary sarcoidosis: challenges and solutions

Background

Sarcoidosis is a chronic multisystem disease of unknown etiology characterized by noncaseating granulomas that most often involves the lungs, but frequently has extrapulmonary manifestations, which might be difficult to treat in individual patients.

Objective

To review different disease manifestations, focusing on extrapulmonary organ systems, and to provide treatment options for refractory cases.

Materials and methods

We performed a literature search using Medline and Google Scholar for individual or combined keywords of “sarcoidosis, extrapulmonary, treatment, kidney, neurosarcoidosis, cardiovascular, gastrointestinal, transplantation, musculoskeletal, rheumatology, arthritis, and skin”. Peer-reviewed articles, including review articles, clinical trials, observational trials, and case reports that were published in English were included. References from retrieved articles were also manually searched for relevant articles.

Results and conclusion

Isolated involvement of a single organ or organ system is rare in sarcoidosis, and thus all patients must be thoroughly evaluated for additional disease manifestations. Cardiac sarcoidosis and neurosarcoidosis may be life-threatening. Clinicians need to assess patients comprehensively using clinical, laboratory, imaging, and histopathological data to recommend competently the best and least toxic treatment option for the individual patient.

[Many faces of sarcoidosis]

Sarcoidosis is a systemic, inflammatory, granulomatous disease of unknown origin that can involve any organ. More than 90% of patients have thoracic sarcoidosis, which most frequently presents with bilateral hilar lymphadenopathy. In approximately 20% of patients with thoracic sarcoidosis there is involvement of the lung parenchyma as well as mostly asymptomatic cardiac sarcoidosis in up to 55% of patients. Most patients are asymptomatic and the diagnosis is an incidental finding on chest X-ray or during clarification of unspecific symptoms, such as fatigue or cough. In approximately two thirds of patients the disease undergoes spontaneous remission and in one third the disease follows a chronic or even progressive course. Furthermore, sarcoidosis can also be manifested in the abdominal organs, the central nervous system (CNS) and the musculoskeletal system. These manifestations are frequently subclinical and require targeted diagnostics when sarcoidosis is clinically suspected.

Necrotizing crescentic glomerulonephritis related to sarcoidosis: a case report

INTRODUCTION

Renal injury due to sarcoidosis develops in less than a quarter of patients with this systemic disease. In most cases, granulomatous tissue alters the production of vitamin D, which leads to hypercalciuria, nephrocalcinosis, and nephrolithiasis. Granulomatous interstitial nephritis is another well-recognized pathological process associated with sarcoidosis. However, a glomerular pathology is very rarely noted, and only a few cases are reported to have cellular crescentic glomerulonephritis.

CASE PRESENTATION

We describe the case of a 26-year-old African American woman with systemic sarcoidosis, with a unique constellation of renal lesions, including noncaseating epithelioid granulomatous necrotizing interstitial nephritis, cellular crescent formation, and necrotizing vasculitis. Immunosuppressive therapy was helpful for alleviating her nephrotic syndrome and maintaining the stability of her renal function over a 30-month period.

CONCLUSION

Glomerular involvement of sarcoidosis needs to be considered in the differential diagnosis in cases of rapidly progressive glomerular nephritis.

Granulomatous interstitial nephritis

Granulomatous interstitial nephritis (GIN) is a rare entity detected in ∼0.5-0.9% of all renal biopsies. GIN has been linked to several antibiotics such as cephalosporins, vancomycin, nitrofurantoin and ciprofloxacin. It is also associated with NSAIDs and granulomatous disorders such as sarcoidosis, tuberculosis, fungal infections, and granulomatosis with polyangiitis. Renal biopsy is critical in establishing this diagnosis, and the extent of tubular atrophy and interstitial fibrosis may aid in determining prognosis. Retrospective data and clinical experience suggest that removal of the offending agent in conjunction with corticosteroid therapy often results in improvement in renal function. We describe a patient with a history of multiple spinal surgeries complicated by wound infection who presented with confusion and rash with subsequent development of acute kidney injury. Urinalysis demonstrated pyuria and eosinophiluria, and renal biopsy revealed acute interstitial nephritis with granulomas. These findings were attributed to doxycycline treatment of his wound infection. This review explores the clinical associations, presentation, diagnosis, and treatment of this uncommon cause of acute kidney injury.

Sarcoidosis presenting with hypercalcaemia following withdrawal of long-term immunosuppression in renal transplantation

Long-term immunosuppression, including corticosteroids, is a hallmark of renal transplantation. We describe a patient who had a failed transplant after 15 years, subsequent graft nephrectomy and withdrawal of his immunosuppression therapy including prednisolone. Within months of complete cessation of prednisolone, he developed hypercalcaemia and subsequent systemic symptoms including ocular, respiratory and dermatological. A skin biopsy demonstrated non-caseating granulomatous lesion and a diagnosis of sarcoidosis was confirmed. Re-commencement with prednisolone resulted in complete resolution of clinical and biochemical features of sarcoidosis. Sarcoidosis is unlikely to present in the immunosuppressed patient. This case highlights that unexplained hypercalcaemia at the time of withdrawal of immunosuppression, including corticosteroids, may be a feature of sarcoidosis.

[Renal diseases in rheumatology]

Renal involvement and renal function disorders are commonplace in patients with rheumatic diseases and are often decisive for the prognosis. Typical nephrological complications in rheumatology are renal manifestations or delayed sequelae of the underlying disease in addition to drug-induced renal failure, e.g. by nonsteroidal anti-inflammatory drugs (NSAIDs). The differentiation from other common causes of disturbed renal function (e.g. diabetes and hypertension) is important and often difficult in individual cases. Renal involvement can be clinically manifested in many different ways. The spectrum ranges from slight functional disorders with, for example discrete erythrocyturia/proteinuria and normal renal function up to rapidly progressive renal failure. The probability of renal damage also varies greatly between different underlying diseases. For example, renal involvement in rheumatoid arthritis is a rarity but in contrast relatively normal in systemic lupus erythematosus. In the course of the differential diagnostics urine sediment, protein values and sonography are still the most important factors and the indications for kidney biopsy should be generously applied. Early initiation of immunosuppression can substantially improve the renal prognosis of inflammatory systemic diseases.

Renal sarcoidosis with limited lung manifestations expressing Propionibacterium acnes antigens in the affected tubulointerstitium

Sarcoidosis is a granulomatous multisystemic disorder of unknown origin that can affect the kidneys. Previous reports from Japan and Europe have indicated a link between Propionibacterium acnes infections and sarcoidosis. Here, we present the case of a 68-year-old woman with hypercalcemia and renal failure. A kidney biopsy was performed, which showed granulomatous tubulointerstitial nephritis with a large nonnecrotic nodule that contained mononuclear inflammatory cells and multinucleated giant cells. Subsequent immunohistochemical analysis revealed intracytoplasmic structures, which strongly indicated the presence of the P acnes antigen. Treatment with methylprednisolone ameliorated the patient's hypercalcemia and renal failure. This case report emphasizes the potential of chronic P acnes infection to cause sarcoidosis.

Oxygen nano-bubble water reduces calcium oxalate deposits and tubular cell injury in ethylene glycol-treated rat kidney

Renal tubular cell injury induced by oxalate plays an important role in kidney stone formation. Water containing oxygen nano-bubbles (nanometer-sized bubbles generated from oxygen micro-bubbles; ONB) has anti-inflammatory effects. Therefore, we investigated the inhibitory effects of ONB water on kidney stone formation in ethylene glycol (EG)-treated rats. We divided 60 rats, aged 4 weeks, into 5 groups: control, the water-fed group; 100 % ONB, the 100 % ONB water-fed group; EG, the EG treated water-fed group; EG + 50 % ONB and EG + 100 % ONB, water containing EG and 50 % or 100 % ONB, respectively. Renal calcium oxalate (CaOx) deposition, urinary excretion of N-acetyl-β-D-glucosaminidase (NAG), and renal expression of inflammation-related proteins, oxidative stress biomarkers, and the crystal-binding molecule hyaluronic acid were compared among the 5 groups. In the control and 100 % ONB groups, no renal CaOx deposits were detected. In the EG + 50 % ONB and EG + 100 % ONB groups, ONB water significantly decreased renal CaOx deposits, urinary NAG excretion, and renal monocyte chemoattractant protein-1, osteopontin, and hyaluronic acid expression and increased renal superoxide dismutase-1 expression compared with the EG group. ONB water substantially affected kidney stone formation in the rat kidney by reducing renal tubular cell injury. ONB water is a potential prophylactic agent for kidney stones.

Atypical sarcoidosis diagnosed by bone marrow biopsy during renal workup for possible multiple myeloma

Sarcoidosis is a multi-organ disease of unknown etiology characterized by non-caseating granulomas. Here we report the case of a 78-year-old white male with a past medical history of diabetes mellitus, hypertension, and chronic kidney disease stage III with a baseline serum creatinine of 2.5 mg/dl. The patient had a prior admission history for acute kidney injury (AKI) attributed to dehydration and medication-induced nephro-toxicities. He presented to the renal clinic for follow-up with acute worsening of chronic kidney failure with a serum creatinine level of 3.5 mg/dl. Examination revealed that he was anemic and mildly hypercalcemic with suppressed parathyroid hormone and had proteinuria of 1.3 g per day. The computed tomography scan of the abdomen revealed right renal pelvic non-obstructing calculi. Serum protein electrophoresis revealed gammopathy with two distinct monoclonal peaks consisting of immunoglobulin G (IgG) kappa and IgG lambda, respectively. The kappa/lambda ratio was within normal limits, and urine protein electrophoresis showed no evidence of a monoclonal peak or Bence Jones proteins. Further workup for multiple myeloma, including bone marrow (BM) biopsy, revealed polyclonal plasma cells and B cells with no clonality. No morphological and immune-phenotypic evidence of plasma cell dyscrasia was found, but BM biopsy did show numerous non-caseating granulomas consistent with sarcoidosis. Skin biopsy from non-scaly 6-mm skin colored papule also showed non-caseating granulomas. The patient had elevated angiotensin-converting enzyme levels (165 ug/l) and an erythrocyte sedimentation rate of 27 mm/h. Kidney biopsy did not show granulomas. The hypercalcemia, proteinuria, and AKI responded well after 2 weeks of 60 mg oral prednisone daily.

Clinicopathological study of glomerular diseases associated with sarcoidosis: a multicenter study

Background

The association between sarcoidosis and glomerular diseases has not been extensively investigated in a large series and the potential features of this uncommon association remain to be determined.

Methods

We retrospectively identified 26 patients with biopsy-proven glomerular lesions that occurred in a sarcoidosis context. Potential remission of glomerular disease and sarcoidosis under specific treatment (steroid and/or immunosuppressive agents) was recorded for all patients. Demographic, clinical and biological characteristics were assessed at the time of kidney biopsy for each patient. Therapeutic data were analyzed for all patients.

Results

Glomerular disease occurred after the diagnosis of sarcoidosis in 11 of 26 cases (42%) (mean delay of 9.7 years). In six patients (23%), the glomerulopathy preceded the sarcoidosis diagnosis (mean delay 8 years). In the last nine patients (35%), both conditions occurred simultaneously. The most frequent glomerular disease occurring in sarcoidosis patients was membranous nephropathy in eleven cases. Other glomerular lesions included IgA nephropathy in six cases, focal segmental glomerulosclerosis in four patients, minimal change nephrotic syndrome for three patients and proliferative lupus nephritis in two patients. Granulomatous interstitial nephritis was associated with glomerular disease in six patients and was exclusively found in patients in whom the both disease occurred simultaneously. In nine patients with simultaneous glomerular and sarcoidosis diseases, we observed a strong dissociation between glomerular disease and sarcoidosis in terms of steroid responsiveness. At the end of the follow-up (mean of 8.4 years), six patients had reached end-stage renal disease and three patients had died.

Conclusions

A wide spectrum of glomerular lesions is associated with sarcoidosis. The close temporal relationship observed in some patients suggests common causative molecular mechanisms of glomerular injury but complete remission of both diseases in response to exclusive steroid therapy is infrequent.

[Kidney involvement in sarcoidosis]

Sarcoidosis is a chronic multisystemic inflammatory disorder of unknown etiology, characterized by the presence of non-necrotizing epithelioid and giant cell granulomas. Various renal manifestations have been reported in patients with sarcoidosis. Disorders of bone and mineral metabolism related to the overexpression of 25-hydroxyvitamin-D1α-hydroxylase by alveolar and granuloma macrophages are frequently associated with sarcoidosis. Hypercalcemia and hypercalciuria are a major cause of renal injury predisposing to pre renal azotemia, acute tubular necrosis, nephrolithiasis and nephrocalcinosis. Therapeutic management of hypercalcemia includes preventive measures (limited sunlight exposure, limited vitamin D and calcium intakes, and adequate hydration) and specific treatment in cases of severe hypercalcemia (corticosteroid therapy, chloroquine or ketoconazole). Granulomatous tubulointerstitial nephritis is the most common renal lesion associated with sarcoidosis leading to end stage renal disease in some patients. In these cases, interstitial fibrosis seems to appear early in the course of sarcoidosis and is a major prognostic factor requiring rapid corticosteroid therapy to reduce the risk of severe renal impairment. Membranous nephropathy seems to be the most frequent glomerular disease that may occur in association with sarcoidosis. Among kidney allograft recipients, the risk of recurrence of granulomatous tubulointerstitial nephritis is high and may have a negative impact on the graft survival.

Immune reconstitution renal-limited sarcoidosis presenting as acute kidney injury

An HIV-infected asymptomatic woman developed acute kidney injury six weeks after initiation of combination antiretroviral therapy (cART). A renal biopsy revealed both renal-limited sarcoidosis and HIV nephropathy. The acute renal injury reversed with glucocorticoid therapy.

Tumor necrosis factor-alpha inhibitor treatment for sarcoidosis

Sarcoidosis is a chronic multisystem disease of unknown etiology, characterized by noncaseating granulomatous infiltration of virtually any organ system. Treatment is often undertaken in an attempt to resolve symptoms or prevent progression to organ failure. Previous studies have suggested a prominent role for tumor necrosis factor-alpha (TNF-α) in the inflammatory process seen in sarcoidosis. TNF-α and interleukin-1 are released by alveolar macrophages in patients with active lung disease. Corticosteroids have proved to be efficacious in the treatment of sarcoidosis, possibly by suppressing the production of TNF-α and other cytokines. Three agents are currently available as specific TNF antagonists: etanercept, infliximab, and adalimumab. Although data from noncomparative trials suggest that all three have comparable therapeutic effects in rheumatoid arthritis, their effects in a granulomatous disease such as sarcoidosis are less consistent. In this review, current data on the effectiveness are summarized.

Renal co-morbidity in patients with rheumatic diseases

Renal co-morbidity is common in patients with rheumatic disease based on regular assessment of serum and urine parameters of renal function. When patients present with both arthritis and renal abnormalities the following questions have to be addressed. Is kidney disease a complication of rheumatic disease or its management, or are they both manifestations of a single systemic autoimmune disease? Is rheumatic disease a complication of kidney disease and its management? How do rheumatic disease and kidney disease affect each other even when they are unrelated? The present review provides an overview of how to address these questions in daily practice.

Renal manifestations of systemic illness in children

Kidney disease may be associated with a systemic disorder or found in isolation. With advances in the understanding of the pathophysiology of glomerular disorders, the distinction between primary and secondary glomerular disease is no longer valid. A wide spectrum of glomerular, vascular, and tubulointerstitial diseases may accompany autoimmune disorders, nephritogenic pharmaceuticals, infections, or complement dysregulation. This article focuses on renal manifestations of systemic diseases such as vasculitis, drug- and infection-related tubulointerstitial injury, and thrombotic disorders.

Tubulointerstitial nephritis associated with IgG4-related autoimmune disease

Autoimmune pancreatitis is a chronic fibroinflammatory condition primarily affecting the pancreas. Recent accumulating evidence suggested that autoimmune pancreatitis is a systemic autoimmune disease (immunoglobulin G4 [IgG4]-related autoimmune disease) affecting various organs with dense infiltration of IgG4-positive mononuclear cells. Tubulointerstitial nephritis is still a mysterious disease with an unknown cause. We report 2 cases of tubulointerstitial nephritis associated with autoimmune pancreatitis. In these patients, dense infiltrations of IgG4-positive mononuclear cells were observed in renal interstitium, with high serum IgG4 levels. Furthermore, in patient 1, who had sclerosing cholangitis, serum alkaline phosphatase and serum creatinine levels changed synchronously. Steroid therapy was followed by improved renal function and serum IgG4 levels in both patients. Because tubulointerstitial nephritis associated with IgG4-related autoimmune disease shows a favorable response to steroids and the renal dysfunction and pancreatic dysfunction are reversible, awareness of this entity is necessary for early diagnosis and prompt treatment. In addition, these cases support the hypothesis that IgG4-related autoimmune disease could be one cause of tubulointerstitial nephritis.

[Renal manifestations in rheumatic diseases]

Inflammatory rheumatic diseases other than systemic vasculitides and systemic lupus erythematosus are frequently associated with renal abnormalities, which are clinically less apparent due to the subtle course and the often only moderate impairment of renal function. These abnormalities include vascular, glomerular and tubulointerstitial changes. Renal manifestations in the course of rheumatoid arthritis influence the prognosis of the disease. Renal involvement due to AA amyloidosis following long-standing inflammatory joint disease can lead slowly, over years, to end-stage renal disease. A scleroderma renal crisis in the course of systemic sclerosis can potentially result in end-stage renal disease within days. The differential diagnosis of renal abnormalities in a rheumatic patient should include drug induced renal impairment as well as infection.

Proposed mechanisms in renal tubular crystal retention

The production of concentrated urine inevitably leads to the precipitation of poorly soluble waste salts in the renal tubular fluid. These crystallization processes are physiologic and without consequences as long as all crystals are excreted with the urine. The retention of crystals in the renal tubules, however, may lead to tubular nephrocalcinosis. Here, we present a brief survey of the possible mechanisms involved in this process, which seems to depend predominantly on the presence of regenerating/(re)differentiating cells in the renal tubules. Crystal binding to the surface of these cells can be mediated by a number of luminal membrane molecules, including acidic fragment of nucleolin-related protein, annexin-II, osteopontin, and hyaluronan.

Sarcoidosis presenting with hearing loss and granulomatous interstitial nephritis in an adolescent

Granulomatous interstitial nephritis is an uncommon finding in a kidney biopsy. The differential diagnosis is broad and includes infections, drug exposure, and sarcoidosis. Sarcoidosis, a systemic disorder of unknown etiology characterized by the presence of noncaseating granulomata in affected organs, is rare in children. We discuss an adolescent boy with the unusual presentation of granulomatous interstitial nephritis and acute deafness. Sarcoidosis should be considered as part of the differential diagnosis for children and adolescents with hearing loss and kidney disease.

Sarcoid tubulo-interstitial nephritis: Long-term outcome and response to corticosteroid therapy

Sarcoidosis is a chronic relapsing multi-systemic disorder characterized by the development of non-caseating granulomas. Granulomatous tubulo-interstitial nephritis is an uncommon manifestation of this condition. We identified 39 patients with sarcoidosis and renal disease from a single center of whom 17 patients had biopsy-proven tubulo-interstitial nephritis. They were analyzed with respect to demographic and clinical features, including response to corticosteroids and length of follow-up. They all presented with significant renal impairment. At presentation the mean+/-s.d. estimated glomerular filtration rate (eGFR) was 26.8+/-14 ml/min by modification of diet in renal disease (MDRD) equation 7. With treatment there was a significant improvement in renal function with eGFR 49.6+/-5.2 ml/min (P<0.01) at 1 year, and 47.9+/-6.8 ml/min (P<0.05) at the last review. The median follow-up was 84 months (range 6-284 months). Patients with chronic kidney disease (CKD) 3, the mean eGFR was 38.30+/-2.4 ml/min at presentation and 60.2+/-7.4 ml/min at 1 year (P=0.02) and in CKD 4 it improved from 19+/-2 to 38+/-6.6 ml/min at 1 year (P<0.05). After the 1st year, the change in eGFR was +0.8 ml/min/year for CKD 3 and -2 ml/min/year for CKD 4 (P<0.05). Three patients ceased their therapy either due to complications or poor compliance and experienced a worsening of renal function which was then reversed on re-commencing corticosteroids. Corticosteroids are effective in advanced tubulo-interstitial nephritis due to sarcoidosis. Long-term treatment is necessary to preserve renal function and to delay the onset of end-stage renal disease.

Crystal Retention in Renal Stone Disease: A Crucial Role for the Glycosaminoglycan Hyaluronan?

The mechanisms that are involved in renal stone disease are not entirely clear. In this article, the various concepts that have been proposed during the past century are reviewed briefly and integrated into current insights. Much attention is dedicated to hyaluronan (HA), an extremely large glycosaminoglycan that may play a central role in renal stone disease. The precipitation of poorly soluble calcium salts (crystal formation) in the kidney is the inevitable consequence of producing concentrated urine. HA is a major constituent of the extracellular matrix in the renal medullary interstitium and the pericellular matrix of mitogen/stress-activated renal tubular cells. HA is an excellent crystal-binding molecule because of its size, negative ionic charge, and ability to form hydrated gel-like matrices. Crystal binding to HA leads to crystal retention in the renal tubules (nephrocalcinosis) and to the formation of calcified plaques in the renal interstitium (Randall's plaques). It remains to be determined whether one or both forms of renal crystal retention are involved in the development of kidney stones (nephrolithiasis).

IgM-immune complex glomerulonephritis associated with sarcoidosis

We present a case of proliferative glomerulonephritis with peculiar IgM deposition associated with sarcoidosis. A 62-year-old woman, who had been diagnosed with sarcoidosis 3 years previously because of abnormalities on chest X-ray radiophotographs and lymph node pathology, was admitted to our hospital for the evaluation of proteinuria and microscopic hematuria. Laboratory findings showed renal dysfunction (creatinine clearance, 52 ml/min), a moderate range of urinary protein (1.51 g/day), and increased serum lysozymes (20.7 microg/ml; normal range, 3.4-8.6 microg/ml). Serum calcium level was within the normal range. Renal biopsy revealed immune complex glomerulonephritis (IgM deposition type) with a membranoproliferative pattern, without granuloma or calcium deposition. Corticosteroid (initial dose of prednisolone [PSL], 1 mg/kg per day) was administered, but neither renal function nor urinary protein improved. She then became nephrotic and her renal function gradually deteriorated. To our knowledge, among uncommon glomerulonephritides with sarcoidosis, five cases of immune complex glomerulonephritis with IgM deposition have been reported. Immune complex glomerulonephritis with IgM deposition is unusual and could be related to sarcoidosis; it may be a characteristic pathology which could provide a clue to elucidate the pathogenesis of sarcoidosis.

Isolated sarcoid granulomatous interstitial nephritis responding to infliximab therapy

Sarcoidosis is a systemic disease with multiorgan involvement. In children, renal impairment of sarcoidosis usually is caused by either hypercalcemia leading to nephrocalcinosis or interstitial nephritis with or without granulomata. We report the case of a 13-year-old boy presenting with severe arterial hypertension and acute renal failure caused by an isolated sarcoid granulomatous interstitial nephritis (GIN). Other known causes of GIN, eg, drug intake or fungal or mycobacterial infection, were excluded, and there was no evidence of extrarenal sarcoid involvement. Renal function improved initially with prednisone treatment. Blood pressure was controlled using ramipril, nifedipine, furosemide, dihydralazine, and metoprolol. Later, the patient showed signs of severe steroid toxicity and progressive renal failure. Monthly treatment with infliximab, a tumor necrosis factor-alpha antibody, was started, resulting in steady improvement in renal function and resolution of renal granulomata. In addition, antihypertensive medication could be reduced, and low-dose prednisone therapy was maintained. To our knowledge, this is the first report of successful treatment with infliximab of a patient with sarcoid GIN.