Nephrotic syndrome associated with hemophagocytic syndrome

Acute kidney injury after CAR-T cell infusion

Chimeric antigen receptor T (CAR-T)-cell, an adaptive immune therapy is approved for patients with acute lymphoblastic leukemia and diffuse large B-cell lymphoma. Its use and subsequent toxicities are expected to rise in the coming years. The main toxicities are cytokine release syndrome, hemophagocytic lymphohistiocytosis and immune effector cell associated neurotoxicity syndrome. Cytokine release syndrome is observed in up to 40% of patients. Almost 20% of patient suffer from acute kidney injury after CAR-T cell infusion. Associated factors are high-grade cytokine release syndrome, a prior autologous or allogeneic stem cell transplantation andrequirement of intensive care unit. Several mechanisms may contribute to the occurrence of acute kidney injury after CAR-T infusion: hypoperfusion during cytokine release syndrome, cytokine injury, T cell infiltration, tumor lysis syndrome and sepsis-induced injury. Kidney injury is associated with substantial increase in morbi-mortality.

Collapsing Glomerulopathy

Collapsing glomerulopathy (CG) is a pattern of kidney injury characterized by segmental or global collapse of the glomerular tuft associated with overlying epithelial cell hyperplasia. Although CG may be idiopathic, a wide range of etiologies have been identified that can lead to this pattern of injury. Recent advances have highlighted the role of inflammatory and interferon signaling pathways and upregulation of apolipoprotein L1 (APOL1) within podocytes in those carrying a high-risk APOL1 genotype. In this review, we describe the etiology, pathogenesis, pathology, and clinical course of CG, focusing on nonviral etiologies. We also describe current treatments and explore potential therapeutic options targeting interferon/APOL1 pathways in CG.

Acute kidney injury in critical care: complications of hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is an immune dysfunction characterized by an exaggerated and pathological inflammatory response, potentially leading to systemic inflammatory reactions and multiple-organ failure, including renal involvement. HLH can be classified as primary or secondary, with primary HLH associated with genetic mutations affecting cell degranulation capacity, and secondary HLH often linked to infections, tumors, and autoimmune diseases. The pathogenesis of HLH is not fully understood, but primary HLH is typically driven by genetic defects, whereas secondary HLH involves the activation of CD8+ T cells and macrophages, leading to the release of inflammatory cytokines and systemic inflammatory response syndrome (SIRS). The clinical presentation of HLH includes non-specific manifestations, making it challenging to differentiate from severe sepsis, particularly secondary HLH due to infections. Shared features include prolonged fever, hepatosplenomegaly, hematopenia, hepatic dysfunction, hypertriglyceridemia, and hypofibrinogenemia, along with histiocytosis and hemophagocytosis. However, distinctive markers like dual hemocytopenia, hypertriglyceridemia, hypofibrinogenemia, and elevated sCD25 levels may aid in differentiating HLH from sepsis. Indeed, no singular biomarker effectively distinguishes between hemophagocytic lymphohistiocytosis and infection. However, research on combined biomarkers provides insights into the differential diagnosis. Renal impairment is frequently encountered in both HLH and sepsis. It can result from a systemic inflammatory response triggered by an influx of inflammatory mediators, from direct damage caused by these factors, or as a consequence of the primary disease process. For instance, macrophage infiltration of the kidney can lead to structural damage affecting various renal components, precipitating disease. Presently, tubular necrosis remains the predominant form of renal involvement in HLH-associated acute kidney injury (HLH-AKI). However, histopathological changes may also encompass interstitial inflammation, glomerular abnormalities, microscopic lesions, and thrombotic microangiopathy. Treatment approaches for HLH and sepsis diverge significantly. HLH is primarily managed with repeated chemotherapy to eliminate immune-activating stimuli and suppress hypercellularity. The treatment approach for sepsis primarily focuses on anti-infective therapy and intensive symptomatic supportive care. Renal function significantly influences clinical decision-making, particularly regarding the selection of chemotherapy and antibiotic dosages, which can profoundly impact patient prognosis. Conversely, renal function recovery is a complex process influenced by factors such as disease severity, timely diagnosis, and the intensity of treatment. A crucial aspect in managing HLH-AKI is the timely diagnosis, which plays a pivotal role in reversing renal impairment and creating a therapeutic window for intervention, may have opportunity to improve patient prognosis. Understanding the clinical characteristics, underlying causes, biomarkers, immunopathogenesis, and treatment options for hemophagocytic lymphohistiocytosis associated with acute kidney injury (HLH-AKI) is crucial for improving patient prognosis.

Concept and Diagnostic Challenges of Renal-Limited Hemophagocytic Syndrome/Macrophage Activation Syndrome

Hemophagocytic syndrome/macrophage activation syndrome (HPS/MAS) is a serious clinical condition that frequently leads to multiple organ failure, including acute kidney injury (AKI). Although the pathogenesis of AKI is not yet fully understood, it is believed to result from uncontrolled activation of the immune system involving macrophages and cytotoxic lymphocytes. Renal histology in HPS/MAS often presents with characteristic foamy glomerular lesions (glomerular lipidosis) with massive macrophage infiltration, known as histiocytic glomerulopathy. In this review, we introduce the recently proposed concept of renal-limited HPS/MAS as a novel etiology of histiocytic glomerular lipidosis. Patients with renal-limited HPS/MAS often develop AKI but do not fulfill the diagnostic criteria for HPS/MAS because their systemic manifestations are less severe. Therefore, the diagnosis largely depends on characteristic histological findings, that is, diffuse and global glomerular accumulation of foamy macrophages and cytotoxic lymphocytes accompanied by the interaction of these cells as well as the exclusion of various differential diseases. Although there are no established therapeutic regimens, these patients receive various types of therapies, including high-dose glucocorticoids, immunosuppressants, or anti-interleukin-1 drug, and generally achieve favorable outcomes. We summarized the concept, diagnostic challenges, and recent topics of this disease entity and discussed treatment options based on our own experiences.

Clinical Features of Cytokine Storm Syndrome

Cytokine storm syndrome (CSS) is a severe life-threatening condition characterized by a clinical phenotype of overwhelming systemic inflammation, hyperferritinemia, hemodynamic instability, and multiple organ failure (MOF), and, if untreated, it can potentially lead to death. The hallmark of CSS is an uncontrolled and dysfunctional immune response involving the continual activation and expansion of lymphocytes and macrophages, which secrete large amounts of cytokines, causing a cytokine storm. Many clinical features of CSS can be explained by the effects of pro-inflammatory cytokines, such as interferon (IFN)-γ, tumor necrosis factor (TNF), interleukin (IL)-1, IL-6, and IL-18 [1-7]. These cytokines are elevated in most patients with CSS as well as in animal models of CSS [8, 9]. A constellation of symptoms, signs, and laboratory abnormalities occurs that depends on the severity of the syndrome, the underlying predisposing conditions, and the triggering agent.

The metabolic effects of APOL1 in humans

Harboring apolipoprotein L1 (APOL1) variants coded by the G1 or G2 alleles of the APOL1 gene increases the risk for collapsing glomerulopathy, focal segmental glomerulosclerosis, albuminuria, chronic kidney disease, and accelerated kidney function decline towards end-stage kidney disease. However, most subjects carrying APOL1 variants do not develop the kidney phenotype unless a second clinical condition adds to the genotype, indicating that modifying factors modulate the genotype-phenotype correlation. Subjects with an APOL1 high-risk genotype are more likely to develop essential hypertension or obesity, suggesting that carriers of APOL1 risk variants experience more pronounced insulin resistance compared to noncarriers. Likewise, arterionephrosclerosis (the pathological correlate of hypertension-associated nephropathy) and glomerulomegaly take place among carriers of APOL1 risk variants, and these pathological changes are also present in conditions associated with insulin resistance, such as essential hypertension, aging, and diabetes. Insulin resistance may contribute to the clinical features associated with the APOL1 high-risk genotype. Unlike carriers of wild-type APOL1, bearers of APOL1 variants show impaired formation of lipid droplets, which may contribute to inducing insulin resistance. Nascent lipid droplets normally detach from the endoplasmic reticulum into the cytoplasm, although the proteins that enable this process remain to be fully defined. Wild-type APOL1 is located in the lipid droplet, whereas mutated APOL1 remains sited at the endoplasmic reticulum, suggesting that normal APOL1 may participate in lipid droplet biogenesis. The defective formation of lipid droplets is associated with insulin resistance, which in turn may modulate the clinical phenotype present in carriers of APOL1 risk variants.

Case report of extranodal natural killer/T-cell lymphoma that induced secondary hemophagocytic syndrome-related histiocytic glomerulopathy

Hemophagocytic syndrome (HPS) is a proliferative disease of the mononuclear macrophage system involving multiple organs and systems. We report a 50-year-old Asian woman who presented with unexplained fever and proteinuria. Laboratory tests showed cytopenia, considerably elevated serum ferritin and IL-2 receptor concentrations, and evidence of hemophagocytosis in the bone marrow. A renal biopsy showed macrophage infiltration into the glomerulus, resulting in podocyte and endothelial cell damage. We finally diagnosed the patient with extranodal natural killer/T-cell lymphoma, nasal type that induced HPS-related histiocytic glomerulopathy. Proteinuria and inflammation responded to treatment with high-dose pulsed methylprednisolone combined with VP-16 and cyclosporine. To the best of our knowledge, this is the first documented case of HPS-related histiocytic glomerulopathy triggered by a malignant tumor.

Streptococcal Infection-related Glomerulonephritis in an Elderly Diabetic Patient Complicated by Hemophagocytic Syndrome and Cytomegalovirus Nephritis

There has been a significant shift in epidemiology and renal outcomes of infection-related glomerulonephritis (IRGN) in recent years. The renal prognosis of IRGN is often poor in adults, especially in the elderly and diabetics. We herein report an elderly diabetic patient with IRGN due to streptococcal infection complicated by hemophagocytic syndrome and cytomegalovirus nephritis, which is uncommon among non-transplant patients. Infection control and steroids did not recover the patient's renal function. For elderly IRGN patients with diabetes, a further investigation of the most effective treatment for related renal outcomes is needed.

Acute Kidney Injury in Cancer Immunotherapy Recipients

Cancer immunotherapy has now entered clinical practice and has reshaped the standard of care for many cancer patients. With these new strategies, specific toxicities have emerged, and renal side effects have been described. In this review, we will describe the causes of acute kidney injury in CAR T cell, immune checkpoint inhibitors and other cancer immuno-therapy recipients. CAR T cell therapy and bispecific T cell engaging antibodies can lead to acute kidney injury as a consequence of cytokine release syndrome, tumor lysis syndrome, sepsis or specific CAR T cell infiltration. Immune checkpoint blockade most often results in acute tubular interstitial nephritis, but glomerular diseases have also been described. Although the pathophysiology remains mostly elusive, we will describe the mechanisms of renal damage in these contexts, its prognosis and treatment. As the place of immunotherapy in the anti-cancer armamentarium is exponentially increasing, close collaboration between nephrologists and oncologists is of utmost importance to provide the best standard of care for these patients.

Renal involvement as a unique manifestation of hemophagocytic syndrome

Renal-limited hemophagocytic syndrome (HPS) is a rare clinical setting characterized by abnormal activation of the immune system. Fever associated with pancytopenia, hepatosplenomegaly with liver dysfunction, and hypofibrinogenemia are usually observed in HPS. From a histological level, the presence of non-malignant macrophages infiltrating bone marrow and organs represents the hallmark of this condition. Non-malignant macrophages are associated with phagocytizing activities involving other blood cells. While primary HPS is usually associated with inherited dysregulation of the immune system, secondary HPS usually occurs in the context of infection or is linked to a neoplastic process. Clinical presentation varies and can potentially lead to life-threatening settings. While renal involvement has frequently been reported, however, detailed descriptions of the kidney manifestations of HPS are lacking. More critically, the diagnosis of HPS is rarely supported by renal biopsy specimens. We report four rare cases of biopsy-proven renal-limited HPS in patients presenting with acute kidney injury (AKI). The available evidence on this topic is critically discussed in light of the possible emergence of an autonomous entity characterized by an isolated kidney involvement.

Molecular signaling pathways, pathophysiological features in various organs, and treatment strategies in SARS-CoV2 infection

Cytokine storms and extra-activated cytokine signaling pathways can lead to severe tissue damage and patient death. Activation of inflammatory signaling pathways during Cytokine storms are an important factor in the development of acute respiratory syndrome (SARS-CoV-2), which is the major health problem today, causing systemic and local inflammation. Cytokine storms attract many inflammatory cells that attack the lungs and other organs and cause tissue damage. Angiotensin-converting enzyme 2 (ACE2) are expressed in a different type of tissues. inhibition of ACE2 activity impairs renin-angiotensin (RAS) function, which is related to the severity of symptoms and mortality rate in COVID-19 patients. Different signaling cascades are activated, affecting various organs during SARS-CoV-2 infection. Nowadays, there is no specific treatment for COVID-19, but scientists have recognized and proposed several treatment alternatives, including applying cytokine inhibitors, immunomodulators, and plasma therapy. Herein, we have provided the detailed mechanism of SARS-CoV-2 induced cytokine signaling and its connection with pathophysiological features in different organs. Possible treatment options to cope with the severe clinical manifestations of COVID-19 are also discussed.

Hemophagocytic Lymphohistiocytosis Associated With Hemolytic Uremic Syndrome in a Child: A Case Report and Systematic Literature Review

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disorder resulting from excessive activation and nonmalignant proliferation of T-lymphocytes and macrophages. Hemolytic uremic syndrome (HUS) is a disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. Reports pertaining to the association between HLH and HUS are rarely published; however, we report on a 4-year-old boy who was diagnosed with both conditions and treated successfully with high-dose steroid and intravenous immunoglobulin. Differentiating HUS from HLH can be challenging because of their clinical similarities. Therefore, prompt diagnosis and immunosuppressive treatment are essential and life-saving to these patients.

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.

Low total cholesterol predicts early death in children with hemophagocytic lymphohistiocytosis

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a rapidly progressive and potentially life-threatening disorder. Identifying risk factors and timely adjustment of the given treatment regimens is critical to reducing the early mortality in HLH patients. Hypocholesterolemia has been reported to be associated with poor prognosis in a variety of critical illnesses. However, serum cholesterol is rarely studied in HLH patients, and its prognostic value is unclear.

METHODS

We conducted a retrospective cohort study in National Clinical Research Center for Child Health and Disorders (Chongqing), identifying pediatric HLH patients (including genetically confirmed pHLH and not genetically confirmed pHLH) diagnosed with the HLH-2004 protocol and treated with immunochemotherapy between January 2008 and December 2020. The patients' blood lipid levels at initial diagnosis of HLH, including triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), were reviewed based on electronic medical records. Both Cox and logistic regression models were used to estimate the effects of blood lipid indicators on early death (within 30 days after diagnosis).

RESULTS

A total of 353 patients were enrolled in the study, with a median age at diagnosis of 45 months. The observed 30-day mortality rate was 19.05% (64/336, 17 were lost to follow-up) and Kaplan-Meier-estimated 3-year survival rate was 61.67% (95% CI, 56.27%-67.59%). DNA-targeted sequencing of HLH-related genes was performed in 173 (49.0%, 173/353) patients (not all patients with suspected pHLH underwent genetic testing), and 29 patients were diagnosed with genetically confirmed pHLH. Lipid panel was performed in 349 patients: 91.98% (321/349) had TG ≥ 1.80 mmol/L, 62.75%(219/349) had TG ≥ 3.00 mmol/L, 92.84% (324/349) had HDL-C ≤ 1.04 mmol/L, 58.74% (205/349) had LDL-C ≤ 1.30 mmol/L and 24.64% (86/349) had TC ≤ 3.11 mmol/L. TC ≤ 3.11 mmol/L and BUN ≥ 7.14 mmol/L were the independent risk factors for 30-day mortality [HR(95%CI): 2.85(1.46, 5.57) and 2.90(1.48, 5.68), respectively]. The presence of one of these risk factors increased the 30-day mortality rate by 6-fold [HR = 6.24, 95%CI: (3.18, 12.22)] and the presence of two risk factors by nearly 10-fold [HR = 9.98, 95%CI: (4.23, 23.56)] compared with the patients with no risk factors.

CONCLUSION

Severe derangement of lipoproteins is common in children with HLH, and decreased TC is an independent risk factor for early death. Hypocholesterolemia should be included as a biomarker during the diagnosis and management of HLH patients.

Histiocytic Glomerulopathy Associated With Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a systemic inflammatory syndrome characterized by heightened activation and proliferation of nonmalignant macrophages and excessive cytokine release. Whereas acute kidney injury is common in this syndrome, direct glomerular involvement by activated histiocytes is very rare. We present the case of a man in his 20s who presented with fevers, malaise, flank pain, anemia, thrombocytopenia, severe acute kidney injury, and proteinuria. A kidney biopsy revealed histiocytic glomerulopathy and subacute thrombotic microangiopathy, and he was diagnosed with HLH. Recovery of kidney function occurred following steroid therapy. A review of kidney involvement by HLH is provided.

Collapsing Focal Segmental Glomerulosclerosis and Acute Kidney Injury Associated With Chimeric Antigen Receptor T-Cell (CAR-T) Therapy: A Case Report

Chimeric antigen receptor T (CAR-T) cell treatment is a rapidly emerging therapy for relapsed/refractory hematologic malignancies. Although cytokine release syndrome is a common complication, a concomitant development of biopsy-proven collapsing glomerulopathy and acute kidney injury (AKI) has not been described with CAR-T cell therapy. We report a man in his early 20s with relapsed/refractory pre–B-cell acute lymphoblastic leukemia and compensated liver cirrhosis who received 3 courses of CD19-directed CAR-T cells. After the third CAR-T cell therapy, he developed severe cytokine release syndrome accompanied by new onset of nephrotic syndrome and AKI. Cytokine release syndrome was treated with tocilizumab. His kidney biopsy showed collapsing glomerulopathy, glomerulitis, and interstitial nephritis along with complete podocyte foot-process effacement. Due to disease progression, he was subsequently treated with bispecific CD19-directed CD3 T-cell engager antibody, blinatumomab, during which he developed another episode of cytokine release syndrome with exacerbation of nephrotic-range proteinuria and his AKI progressed to stage 3 chronic kidney disease. Excess cytokine-induced podocyte and renal tubulointerstitial injury and/or “on-target off-tumor” direct renal cell toxicity are the probable mechanisms of kidney injury. Further such reports will increase our understanding of the pathophysiologic basis of kidney injury with CAR-T treatment.

Hemophagocytic lymphohistiocytosis and thrombotic microangiopathy after parvovirus B19 infection and renal transplantation: a case report

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening disease characterized by hyperactivation of the immune system that causes hypercytokinemia and potentially multi organ failure. HLH can occur in patients with underlying rheumatic or autoinflammatory disorders. Additionally, HLH can develop in patients during infections or malignancies without a known genetic predisposition.

CASE PRESENTATION

We herein report a patient, who presented with fever, both acute kidney and liver injury, anemia, thrombocytopenia and HSV stomatitis. HLH was diagnosed based on clinical criteria and qPCR revealed an acute parvovirus B19 infection as potential underlying infectious trigger. Treatment was started with both IVIG and dexamethasone. Subsequently, kidney biopsy demonstrated TMA.

CONCLUSIONS

In rare cases both HLH and aHUS can occur simultaneously in a patient as a consequence of viral infections. Insights from this unusual case might help physicians understand this complex symptom constellation.

Hemophagocytic syndrome triggered by donor-transmitted toxoplasmosis as a complication in same-donor recipients of renal transplantation: Case report and review of the literature

BACKGROUND

Hemophagocytic syndrome (HPS) is an infrequent complication of transplantation caused by an inflammatory response with a benign proliferation of macrophages and defective lytic capability of T lymphocytes and NK cells that can lead to multiorgan failure. Transplant patients are particularly exposed as a result of the increased risk of both infections and malignancies derived from immunosuppressive drugs. There is no consensus for therapy or immunosuppression; mortality is high. We report a case and present a review of all cases of HPS occurring in solid organ transplant recipients.  CASE REPORT: We report two cases of infection by Toxoplasma gondii transmitted by the kidney allograft. One of the recipients was seronegative before transplantation and developed disseminated primary toxoplasmosis. An immune reaction compatible with an HPS ensued. Both were treated with Trimethoprim/sulfamethoxazole, immunosuppression was tapered, and after a 2-week period a complete response was obtained.

CONCLUSION

HPS presents therapeutic challenges in the context of transplantation. If HPS is suspected, the search of a very likely underlying infection should be central to the management.

Ruxolitinib is an alternative to etoposide for patient with hemophagocytic lymphohistiocytosis complicated by acute renal injury: A case report

INTRODUCTION

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening syndrome characterized by excessive production of inflammatory cytokines and multiple organs injury. Ruxolitinib, an oral selective JAK1/2 inhibitor, has recently shown efficacy and safety in the treatment of secondary HLH, which may be an alternative to intensive chemotherapy.

CASE REPORT

We report a case of a 2-year-old boy who presented to our institution with recurrent fever and acute renal failure. We made the diagnosis of Epstein-Barr virus related HLH based on the HLH-2004 protocol, and gave the treatment of ruxolitinib instead of etoposide.

MANAGEMENT AND OUTCOME

The patient received dexamethasone and continuous renal replacement therapy due to renal failure, but he still had fever and anuria. Given that the use of etoposide may deteriorate renal function, ruxolitinib was administered instead of etoposide. After 5 days of ruxolitinib treatment, the patient's fever was resolved and renal function also gradually recovered 14 days later.

DISCUSSION

Currently, dexamethasone, etoposide and cyclosporine A are the main drugs in HLH treatment. However, cytotoxic chemotherapy can temporally deteriorate organ damage and induce serious myelosuppression, which makes clinicians hesitate to implement these regimens. Ruxolitinib has shown efficacy in treating HLH without much toxicity in clinical trials. Thus, we suggest that ruxolitinib constitutes a treatment option for secondary HLH complicated by severe renal damage which may reduce toxic effects compared with intense chemotherapy.

Current status of the diagnosis and treatment of hemophagocytic lymphohistiocytosis in adults

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of defective apoptosis, a disruption of the regulatory pathway that terminates immune and inflammatory responses. Fever, cytopenia, splenomegaly, and/or hemophagocytosis are typical findings of this syndrome. HLH can be induced by genetic disorders (familial) or secondary causes. Familial HLH is rare, while secondary causes in adults include infection, autoimmunity, and malignancy. HLH in adults tends to be confused with or misdiagnosed as sepsis, mainly due to similar clinical manifestations and laboratory findings, which make it difficult to diagnose HLH rapidly and adopt immunosuppressive agents and/or chemotherapy adequately. Treatment of pediatric HLH using HLH-2004 or multi-agent chemotherapy can be applied in adult patients, although the dose and type of drug need to be adjusted. It is highly recommended that allogenic hematopoietic stem cell transplantation should be used in patients who become reactivated or are refractory to the initial treatment as soon as possible to improve survival. Future clinical trials are warranted to determine more suitable treatments for adult patients with HLH.

Renal Diseases Associated with Hematologic Malignancies and Thymoma in the Absence of Renal Monoclonal Immunoglobulin Deposits

In addition to kidney diseases characterized by the precipitation and deposition of overproduced monoclonal immunoglobulin and kidney damage due to chemotherapy agents, a broad spectrum of renal lesions may be found in patients with hematologic malignancies. Glomerular diseases, in the form of paraneoplastic glomerulopathies and acute kidney injury with various degrees of proteinuria due to specific lymphomatous interstitial and/or glomerular infiltration, are two major renal complications observed in the lymphoid disorder setting. However, other hematologic neoplasms, including chronic lymphocytic leukemia, thymoma, myeloproliferative disorders, Castleman disease and hemophagocytic syndrome, have also been associated with the development of kidney lesions. These renal disorders require prompt recognition by the clinician, due to the need to implement specific treatment, depending on the chemotherapy regimen, to decrease the risk of subsequent chronic kidney disease. In the context of renal disease related to hematologic malignancies, renal biopsy remains crucial for accurate pathological diagnosis, with the aim of optimizing medical care for these patients. In this review, we provide an update on the epidemiology, clinical presentation, pathophysiological processes and diagnostic strategy for kidney diseases associated with hematologic malignancies outside the spectrum of monoclonal gammopathy of renal significance.

Proteinuria and Clinical Outcomes in Hospitalized COVID-19 Patients: A Retrospective Single-Center Study

BACKGROUND AND OBJECTIVES

Kidney involvement is frequent among patients with coronavirus disease 2019 (COVID-19), and occurrence of AKI is associated with higher mortality in this population. The objective of this study was to describe occurrence and significance of proteinuria in this setting.

DESIGN , SETTING, PARTICIPANTS MEASUREMENTS

We conducted a single-center retrospective study to describe the characteristic features of proteinuria measured within 48 hours following admission among patients with COVID-19 admitted in a tertiary care hospital in France, and to evaluate its association with initiation of dialysis, intensive care unit admission, and death.

RESULTS

Among 200 patients with available data, urine protein-creatinine ratio at admission was ≥1 g/g for 84 (42%), although kidney function was normal in most patients, with a median serum creatinine of 0.94 mg/dl (interquartile range, 0.75-1.21). Median urine albumin-creatinine ratio was 110 mg/g (interquartile range, 50-410), with a urine albumin-protein ratio <50% in 92% of patients. Urine retinol binding protein concentrations, available for 85 patients, were ≥0.03 mg/mmol in 62% of patients. Urine protein-creatinine ratio ≥1 g/g was associated with initiation of dialysis (odds ratio, 4.87; 95% confidence interval, 2.03 to 13.0; P <0.001), admission to the intensive care unit (odds ratio, 3.55; 95% confidence interval, 1.93 to 6.71; P <0.001), and death (odds ratio, 3.56; 95% confidence interval, 1.90 to 6.54; P <0.001).

CONCLUSIONS

Proteinuria is very frequent among patients admitted for COVID-19 and may precede AKI. Low levels of albuminuria suggest a predominant tubular origin, confirmed by the elevated levels of urine retinol binding protein. Urine protein-creatinine ratio ≥1 g/g at admission is strongly associated with poor kidney and patient outcome.

Pathogenesis of coronavirus disease 2019-associated kidney injury

PURPOSE OF REVIEW

The current review summarizes the pathologic findings in kidneys from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected patients who have had autopsies or undergone biopsy, and the pathogenic mechanisms implicated in coronavirus disease 2019 (COVID-19)-associated kidney diseases.

RECENT FINDINGS

Direct infection of the kidney by SARS-CoV-2 is not common, and convincing morphologic evidence of substantive kidney infection by SARS-CoV-2 is lacking. Severe COVID-19-associated acute kidney injury is likely multifactorial and results from the physiologic disturbances and therapies used to treat this illness. COVID-19-associated collapsing glomerulopathy (COVAN) is seen almost exclusively in patients with apolipoprotein L1 high-risk genotypes with no evidence of direct infection of the kidney by SARS-CoV-2.

SUMMARY

The prevailing evidence does not support substantive or persistent infection of kidneys in COVID-19 and indirect means of tissue injury are favored, although a 'hit and run' model cannot be excluded. COVAN frequently occurs in patients with mild respiratory systems, suggesting that innate and adaptive immune responses to SARS-CoV-2 infection may provide the second hit needed for the development of collapsing glomerulopathy in susceptible individuals.

Thrombotic microangiopathy led to acute kidney injury in an infant with hemophagocytic lymphohistiocytosis: A case report

Hemophagocytic lymphohistiocytosis (HLH) is a rare but fatal clinical syndrome frequently complicated by acute kidney injury (AKI) and acute tubular necrosis. Renal thrombotic microangiopathy (TMA) is a specific pathological feature of childhood HLH and few cases have been reported among infants. The present study presents a rare case of HLH with TMA in an infant. A 15-month-old infant with a week-long history of fever was admitted to hospital. The infant presented with AKI and subsequently a reduction in platelet and hemoglobin levels. TMA was diagnosed by kidney biopsy and the clinical, laboratory and bone marrow biopsy findings met the criteria of HLH. Due to a progressive increase in serum creatinine levels, hemodialysis was initiated on the second day following admission. Dexamethasone was administered to treat both the fever and HLH. The patient's body temperature returned to a normal range and platelet and hemoglobin levels were stable after 14 days of admission. Renal function stabilized on day 21. The results of genetic testing did not identify any disease-related variations. Childhood HLH is a severe condition and mortality can be reduced by early diagnosis and correct treatment. For patients with HLH and AKI, the possible role of TMA should be considered. Renal biopsy can help to identify the cause of AKI and can be performed when the patient's condition is stable.

Kidney injury in COVID-19

Coronavirus disease 2019 (COVID-19) continues to affect millions of people around the globe. As data emerge, it is becoming more evident that extrapulmonary organ involvement, particularly the kidneys, highly influence mortality. The incidence of acute kidney injury has been estimated to be 30% in COVID-19 non-survivors. Current evidence suggests four broad mechanisms of renal injury: Hypovolaemia, acute respiratory distress syndrome related, cytokine storm and direct viral invasion as seen on renal autopsy findings. We look to critically assess the epidemiology, pathophysiology and management of kidney injury in COVID-19.

Haematological disorders following kidney transplantation

Transplantation offers cure for some haematological cancers, end-stage organ failure, but at the cost of long-term complications. Renal transplantation is the best-known kidney replacement therapy and it can prolong end-stage renal disease patient lives for decades. However, patients after renal transplantation are at a higher risk of developing different complications connected not only with surgical procedure but also with immunosuppressive treatment, chronic kidney disease progression and rejection processes. Various blood disorders can develop in post-transplant patients ranging from relatively benign anaemia through cytopenias to therapy-related myelodysplasia and acute myeloid leukaemia (AML) and post-transplant lymphoproliferative disorders followed by a rare and fatal condition of thrombotic microangiopathy and haemophagocytic syndrome. So far literature mainly focused on the post-transplant lymphoproliferative disease. In this review, a variety of haematological problems after transplantation ranging from rare disorders such as myelodysplasia and AML to relatively common conditions such as anaemia and iron deficiency are presented with up-to-date diagnosis and management.

Bile Cast Nephropathy Secondary to Hemophagocytic Lymphohistiocytosis With Liver Failure

Acute kidney injury (AKI) is a common complication seen in patients with hemophagocytic lymphohistiocytosis (HLH). More than half of patients with HLH require renal replacement therapy (RRT). There are four main causes of kidney dysfunction in HLH, which include acute tubular necrosis (ATN), hypoperfusion, tumor lysis syndrome (TLS), and HLH-related glomerulopathies. Bile cast nephropathy (BCN) is a known cause of kidney injury in patients with liver failure and hyperbilirubinemia. We present the case of a 58-year-old man who presented to the hospital with painless jaundice, choluria, acholia, and generalized malaise and was found to have hyperbilirubinemia and kidney injury in the setting of HLH, who underwent a renal biopsy showing bile salt casts with degenerating tubular lining cells consistent with BCN. This case highlights the importance of considering BCN as a cause of kidney injury when a patient with HLH presents with liver failure and elevated bilirubin levels.

Hemophagocytic syndrome with histiocytic glomerulopathy associated with ovarian serous carcinoma

Histiocytic glomerulopathy, an entity characterized by glomerular infiltration by foamy histiocytes with endothelial injury, has recently been reported as a manifestation of hemophagocytic syndrome. We report a case of histiocytic glomerulopathy in a woman receiving chemotherapy for ovarian serous carcinoma with proteinuria in whom hemophagocytic syndrome was not clinically suspected.

Malaria, Collapsing Glomerulopathy, and Focal and Segmental Glomerulosclerosis

BACKGROUND AND OBJECTIVES

Malaria, a potentially life-threatening disease, is the most prevalent endemic infectious disease worldwide. In the modern era, the spectrum of glomerular involvement observed in patients after malarial infections remains poorly described.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We therefore performed a retrospective multicenter study to assess the clinical, biologic, pathologic, and therapeutic characteristics of patients with glomerular disease demonstrated by kidney biopsy in France within 3 months of an acute malaria episode.

RESULTS

We identified 23 patients (12 men), all but 1 of African ancestry and including 10 patients with concomitant HIV infection. All of the imported cases were in French citizens living in France who had recently traveled back to France from an endemic area and developed malaria after their return to France. Eleven patients had to be admitted to an intensive care unit at presentation. Plasmodium falciparum was detected in 22 patients, and Plasmodium malariae was detected in 1 patient. Kidney biopsy was performed after the successful treatment of malaria, a mean of 24 days after initial presentation. At this time, all patients displayed AKI, requiring KRT in 12 patients. Nephrotic syndrome was diagnosed in 17 patients. Pathologic findings included FSGS in 21 patients and minimal change nephrotic syndrome in 2 patients. Among patients with FSGS, 18 had collapsing glomerulopathy (including 9 patients with HIV-associated nephropathy). In four patients, immunohistochemistry with an antibody targeting P. falciparum histidine-rich protein-2 demonstrated the presence of the malaria antigen in tubular cells but not in podocytes or parietal epithelial cells. An analysis of the apoL1 risk genotype showed that high-risk variants were present in all seven patients tested. After a mean follow-up of 23 months, eight patients required KRT (kidney transplantation in two patients), and mean eGFR for the other patients was 51 ml/min per 1.73 m².

CONCLUSIONS

In patients of African ancestry, imported Plasmodium infection may be a new causal factor for secondary FSGS, particularly for collapsing glomerulopathy variants in an APOL1 high-risk variant background.

Adult Hemophagocytic Lymphohistiocytosis in Sub-Saharan Area: A Retrospective Study of 26 cases

Introduction and background

Hemophagocytic lymphohistiocytosis (HLH) is a condition caused by inappropriate stimulation of macrophage cells with hemophagocytosis. This paper aims to describe its diagnostic specifics and etiology and seeks to identify the factors that affect its prognosis in the black African adult population.

Methods 

A retrospective multicentre study was carried out in three medical units in Senegal: Department of Internal Medicine at Pikine Teaching Hospital, and Department of Internal Medicine and Department of Nephrology at Aristide Le Dantec Teaching Hospital; the study covered the period from January 1, 2012 to March 30, 2015. This study included patients aged 18 years and older with a Hemophagocytosis Score (HScore) of ≥202 (with probabilities of acquired HLH of >90%). The data was obtained through medical records.

Results

In total, 26 patient files were included. The average age of the patients was 41 years, with a male-to-female ratio of 2.25:1. Fever and cytopenia were frequent. Other clinical signs included peripheral lymphadenopathy (69.2%), hepatomegaly (53.8%), splenomegaly (34.6%), neurological disorders (34.5%), and respiratory disorders (15.3%). Thrombocytosis was noted in three cases. Renal involvement was present in eight patients, with one case of collapsing glomerulopathy. The bone marrow aspirate revealed myelodysplasia in 12 patients. The dominant etiologies of HLH were hematological malignancies and infections. The mortality rate of HLH was 73%. Male gender and non-etiological targeted therapy were significantly associated with mortality. However, the age of <40 years in patients and current systemic disease in some cases were correlated with survival. The use of etoposide had no significant impact on the prognosis of our patients.

Conclusion

A high rate of male predominance, important central nervous system disorders, myelodysplasia, and paradoxical thrombocytosis were found to be the distinct features of adult HLH in our study population.

[Adult-onset Still's disease complications]

Adult-onset Still's disease (AOSD), first described in 1971 by Bywaters, is a rare systemic auto-inflammatory disorder of unknown etiology, characterized by a symptomatic triad associating prolonged fever, polyarthritis and rash. The management of this disease has significantly improved since its first description, and, although the overall prognosis of the AOSD is good, with a low attributable mortality, below 3% (but up to 18% depending on the series), some rare complications are still possible, can be life-threatening and change the prognosis of the disease. A literature search was performed to review AOSD's complications: reactive hemophagocytic lymphohystiocytosis, coagulation disorders, fulminant hepatitis, cardiovascular (pericarditis, myocarditis, HTAP) or pulmonary complications, neurologic, renal complications, and AA amyloidosis. For most of AOSD-related complications, corticosteroids remain the first-line treatment, in association with supportive care measures in case of severe complications. In case of inadequate response, multidisciplinary care with concil from a referral center is advised, and IL-1 or IL-6 blockers, but also ciclosporine, are the molecule to use in second intention.

Nephrotoxic Chemotherapy Agents: Old and New

In the last several decades, advancements in chemotherapy have improved the overall survival of cancer patients. These agents, however, are associated with adverse effects, including various kidney lesions. This review summarizes the nephrotoxic potential of chemotherapy agents, old and new, as well as the different factors that contribute to kidney injury. Provided for each class of chemotherapy agent is the associated kidney lesion and a brief discussion of clinical manifestation, mechanism of action, and possible treatment when available. Understanding the nephrotoxic potential of these agents have on the kidneys is imperative for both the oncologist and the nephrologist to properly care for cancer patients and ensure their best outcomes.

Linfohistiocitosis hemofagocítica en trasplante renal

La linfohistiocitosis hemofagocítica (LHH) posterior al trasplante renal hace referencia a un estado hiperinflamatorio grave, asociado a la activación no controlada de los linfocitos T citotóxicos y macrófagos por causa infecciosas y/o secundaria al tratamiento inmunosupresor. Las causas más prevalentes dentro de las infecciones son la histoplasmosis, la tuberculosis y las infecciones por virus herpes. Se caracteriza por fiebre, organomegalias, citopenias, hiperferritinemia, hipertrigliceridemia y/o hipofibrinogenemia; puede acompañarse con hemofagocitosis documentada en la médula ósea, el hígado u otros órganos. Su curso puede ser fulminante con progresión a falla multisistémica y la muerte.El tratamiento va enfocado a controlar tempranamente la causa desencadenante, reducir la inmunosupresión y controlar la inflamación. En pocos casos es necesario el uso de otros inmunosupresores, quimioterapia o, en situaciones muy seleccionadas, se puede requerir el trasplante de médula ósea.

Hemophagocytic syndrome with acute kidney injury accompanied by erythrophagocytic macrophages in the tubular lumen

Hemophagocytic syndrome (HPS) is a life-threatening syndrome involving excessive immune activation. It is often accompanied by renal involvement known as acute kidney injury (AKI), which is a poor prognostic factor of HPS. Thus, early diagnosis and treatment are very important. However, it is rarely identified in renal biopsy specimens, and its major manifestation is acute tubular necrosis. We report a rare case of erythrophagocytic macrophage presence in the tubular lumen of a patient with HPS-associated AKI. A kidney biopsy showed acute tubular necrosis, interstitial massive macrophage infiltration, and phagocytic macrophage casts without glomerular change. Some arteriolar vascular smooth muscle cells showed vacuolization because they were positive for α-smooth muscle actin. The patient's renal function improved after methylprednisolone pulse therapy followed by oral prednisolone after a month. Our case presents a new pathologic pattern of HPS. Careful urinalysis could suggest renal involvement with HPS. Having knowledge of this pathologic pattern of HPS is important to recognize the disease and to treat it appropriately.

Haemophagocytic lymphohistiocytosis with collapsing lupus podocytopathy as an unusual manifestation of systemic lupus erythematosus with APOL1 double-risk alleles

Haemophagocytic lymphohistiocytosis (HLH) is a potentially life-threatening syndrome caused by excessive immune activation. Secondary HLH has been described in autoimmune diseases. We detail the case of a 28-year-old African American woman who developed HLH in the setting of systemic lupus erythematosus with collapsing lupus podocytopathy superimposed on mesangial proliferative lupus nephritis class II. Genotyping for APOL1 risk alleles revealed the presence of double (G1/G2) risk alleles. Our patient achieved a complete renal recovery and resolution of HLH within 1 month of treatment with steroids and mycophenolate mofetil, highlighting the importance of prompt, aggressive therapy.

Collapsing glomerulopathy: update

Collapsing glomerulopathy (CG) is a rare entity as a glomerular disease. Although it has been considered as a variant of focal segmental glomerulosclerosis, the fact is that the podocyte lesions show different features with respect to the typical focal segmental glomerulosclerosis, an aspect that has been attributed to a type of podocytopathy. In CG, the podocyte lesion is typically characterised by a dysregulated podocyte phenotype, reflected by the loss of expression of mature podocyte markers. CG can be a primary disease or it can be associated with several causal factors that develop a common histopathological entity. The clinical expressiveness of CG is often characterised by the presence of a nephrotic syndrome and a rapid deterioration of the renal function than other variants of the focal segmental glomerulosclerosis. The prognosis of these patients is a rapid progression towards end-stage renal disease with poor response to treatment.

Collapsing glomerulonephritis with podocyte markers in hemophagocytic syndrome secondary to hepatosplenic T-cell lymphoma

The hemophagocytic syndrome is a serious clinical-histological entity secondary to different diseases. Collapsing glomerulonephritis is a proliferative podocytopathy that usually has an unfavorable renal prognosis. We present a case in which both entities were associated, which is an infrequent form of hepatosplenic T-cell lymphoma. In addition, we review the role of the markers of podocyte dedifferentiation in this glomerulopathy and its pathophysiology and treatment.

Management of Hemophagocytic Lympho-Histiocytosis in Critically Ill Patients

Hemophagocytic syndrome remains a rare but life-threatening complication and is associated with intensive care unit (ICU) admission. The pathophysiology is based on a defect of cytotoxicity in T cells that results in a state of hyperinflammation in the presence of a trigger. As a consequence, patients may develop multiorgan failure. The diagnosis of hemophagocytic syndrome (HS) remains difficult and relies on persistant high-grade fevers in the absence of infection and on constellation of laboratory parameters. However, prompt diagnosis and treatment (supportive care and specific treatment) are associated with improved outcome. Interaction with other specialists (hematologist, internist) may improve the diagnosis and treatment strategy. This article describes diagnostic tools, organ failures associated with HS, main etiologies, and management.

Donor APOL1 high-risk genotypes are associated with increased risk and inferior prognosis of de novo collapsing glomerulopathy in renal allografts

Collapsing focal segmental glomerulosclerosis (cFSGS) in the native kidney is associated with heavy proteinuria and accelerated renal failure. However, cFSGS in the renal allograft is less well characterized. Here we report clinico-pathologic features and APOL1 donor risk genotypes in 38 patients with de novo post-kidney transplant cFSGS. Recipients were 34% female and 26% African American. Concurrent viral infections and acute vaso-occlusion (including thrombotic microangiopathy, cortical necrosis, atheroembolization, and cardiac arrest with contralateral graft thrombosis) were present in 13% and 29% of recipients, respectively. Notably, 61% of patients had concurrent acute rejection and 47% received grafts from African American donors, of which 53% carried APOL1 high-risk genotypes. These frequencies of acute rejection and grafts from African American donors were significantly higher than in our general transplant population (35% and 16%, respectively). Patients had a median serum creatinine of 5.4 mg/dl, urine protein/creatinine 3.5 g/g, and 18% had nephrotic syndrome. Graft failure occurred in 63% of patients at an average of eighteen months post-index biopsy. By univariate analysis, donor APOL1 high-risk genotypes, post-transplant time, nephrotic syndrome, and chronic histologic changes were associated with inferior graft survival while acute vaso-occlusion was associated with superior graft survival. Donor APOL1 high-risk genotypes independently predicted poor outcome. Compared to native kidney cFSGS, post-transplant cFSGS had more acute vaso-occlusion but less proteinuria. Thus, de novo cFSGS is associated with variable proteinuria and poor prognosis with potential predisposing factors of African American donor, acute rejection, viral infection and acute vaso-occlusion. Additionally, donor APOL1 high-risk genotypes are associated with higher incidence and worse graft survival.

[Cytomegalovirus myositis complicated with hemophagocytic lymphohistiocytosis, acute renal failure, and colitis]

A 60-years-old previously healthy man presented with acute renal failure and hemophagocytic lymphohistiocytosis (HLH). Both conditions improved after immunotherapies, but severe limb weakness with elevation of serum CK developed. Needle EMG showed myogenic changes with spontaneous activities and muscle weakness thereafter improved without adding further immunotherapies, suggesting that our patient had viral myositis. After the stabilization of limb weakness, cecal perforation occurred due to cytomegalovirus (CMV) enteritis and temporal significant change of anti-CMV IgG antibody titer was confirmed using paired serum samples. Upregulation of MHC-class I molecule and numerous regenerative muscle fibers were observed in muscle biopsy, but no evidence of direct CMV infection in muscle fibers were seen. Although CMV infection may cause either myositis, acute renal failure, HLH or colitis in individual patient, this is the first case which had been complicated by all these conditions subsequent to CMV infection.

Atteinte rénale du syndrome d’activation macrophagique

Le syndrome d’activation macrophagique (SAM) ou syndrome hémophagocytaire est une pathologie compliquant soit certains déficits immunitaires d’origine génétique, soit certaines maladies hématologiques (essentiellement des lymphomes non hodgkiniens), infectieuses (herpèsvirus, bactéries, parasites) ou auto-immunes (lupus, maladie de Still). Il se caractérise par une suractivation aiguë du système immunitaire et plus particulièrement des lymphocytes T cytotoxiques et des cellules histiocytaires/macrophagiques, déclenchant une production massive de cytokines pro-inflammatoires avec fièvre, pancytopénie, organomégalie, altérations du bilan hépatique et de la coagulation. Une défaillance multiviscérale est fréquente, nécessitant la prise en charge en réanimation et mettant souvent en jeu le pronostic vital, avec une mortalité qui reste dans certains cas à près de 50 %. Le SAM implique souvent le rein, par le biais d’une nécrose tubulaire aiguë, d’une néphropathie interstitielle inflammatoire ou d’une glomérulopathie sévère, responsable de syndrome néphrotique. La mise en évidence de ce syndrome n’est pas toujours facile chez un patient avec un tableau de sepsis ou de choc septique, mais elle peut guider la prise en charge thérapeutique, notamment l’initiation d’un traitement par chimiothérapie ou immunosuppresseurs, selon l’étiologie identifiée.

Minimal Change Disease as Initial Presentation of ALK-Positive Anaplastic Large-Cell Lymphoma in a Pediatric Patient

The association between nephrotic syndrome (NS), hemophagocytic lymphohistiocytosis (HLH), and certain paraneoplastic syndromes has been documented in the literature. However, nephrotic changes as part of paraneoplastic syndromes are rare in lymphoid malignancies, particularly in non-Hodgkin lymphoma. We report the sudden onset of acute renal failure and NS in a 14-year-old male who initially presented with HLH and was subsequently diagnosed with ALK-positive anaplastic large-cell lymphoma (ALCL). The treatment of ALCL reversed both the HLH and NS findings. This case demonstrates the importance of considering lymphoma in pediatric patients presenting with NS and HLH.

Collapsing glomerulopathy, the Saudi Arabian scenario. A study of 31 cases and a review of literature

Objectives:

To compare the clinico-pathological features of collapsing glomerulopathy (CG) at a tertiary hospital in Saudi Arabia with the world literature.

Methods:

In a retrospective study, all biopsy-diagnosed cases of CG between 2004-2015 were identified and analyzed, at King Khalid University Hospital, King Saud University, Riyadh. The clinico-pathological findings along with prognosis were reviewed and compared with the reported literature.

Results:

Thirty-one CG patients were identified, most were adult males. All the CG cases were idiopathic, all Arabs, none HIV positive, none of African descent, and none with a history of drug abuse. The number of glomeruli with collapsing lesions per biopsy ranged from 1 to 9. Other types of FSGS lesions (not otherwise specified and perihilar) were also noted. There was extensive podocyte effacement. Upon treatment, remission (complete/partial) was noted in almost half the patients; around one fourth did not respond to treatment; and one fourth progressed to end stage kidney disease (ESKD). The median time taken to develop ESKD from the time of biopsy diagnosis was 23 months.

Conclusion:

The clinico-pathological and prognostic correlates of CG in Saudi Arabia are comparable with that of the world literature. The management protocol at our center is the same as that practiced in different parts of the world, and the prognosis is overall poor.

Capillary leak syndrome: etiologies, pathophysiology, and management

In various human diseases, an increase in capillary permeability to proteins leads to the loss of protein-rich fluid from the intravascular to the interstitial space. Although sepsis is the disease most commonly associated with this phenomenon, many other diseases can lead to a "sepsis-like" syndrome with manifestations of diffuse pitting edema, exudative serous cavity effusions, noncardiogenic pulmonary edema, hypotension, and, in some cases, hypovolemic shock with multiple-organ failure. The term capillary leak syndrome has been used to describe this constellation of disease manifestations associated with an increased capillary permeability to proteins. Diseases other than sepsis that can result in capillary leak syndrome include the idiopathic systemic capillary leak syndrome or Clarkson's disease, engraftment syndrome, differentiation syndrome, the ovarian hyperstimulation syndrome, hemophagocytic lymphohistiocytosis, viral hemorrhagic fevers, autoimmune diseases, snakebite envenomation, and ricin poisoning. Drugs including some interleukins, some monoclonal antibodies, and gemcitabine can also cause capillary leak syndrome. Acute kidney injury is commonly seen in all of these diseases. In addition to hypotension, cytokines are likely to be important in the pathophysiology of acute kidney injury in capillary leak syndrome. Fluid management is a critical part of the treatment of capillary leak syndrome; hypovolemia and hypotension can cause organ injury, whereas capillary leakage of administered fluid can worsen organ edema leading to progressive organ injury. The purpose of this article is to discuss the diseases other than sepsis that produce capillary leak and review their collective pathophysiology and treatment.