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The association between Takayasu’s arteritis and membranous nephropathy is uncommon. We present the case of a 46-year-old man with Takayasu’s arteritis treated over 10 years by a multidisciplinary medical team. He had an atrophic left kidney due to arterial stenosis, with a basal creatinine of 1.59 mg/dL (140.55 µmol/l). Three years ago, he presented with full nephrotic syndrome, uncontrolled blood pressure, creatinine increases to 4.5 mg/dL (basal: 1.59 mg/dL), severe hypoalbuminaemia (1.4 g/dL) and albuminuria of 24.6 g per day. He underwent percutaneous biopsy of the right kidney that showed membranous nephropathy with negative PLA2R1 and positive IgG 1, 3 and 4 subclasses. After therapy with oral prednisone and cyclophosphamide, the patient’s kidney function improved, without recurrence of disease after 3 years of follow-up. Here, we present this extremely uncommon association of Takayasu’s arteritis and membranous nephropathy.

Light chain (LC) cast nephropathy is the main cause of kidney injury and an important determinant of poor survival in patients with multiple myeloma (MM). It is usually suspected when an MM patient with elevated serum concentration of free LC presents kidney failure, but it often requires confirmation by kidney biopsy. We report the case of a 73-year-old woman who presented with fatigue, weight loss, and constipation. Laboratory exams revealed anemia, hypercalcemia, and kidney failure. Urine sediment analysis demonstrated irregular crystalline "waxy type" casts. With the hypothesis of LC cast nephropathy, immunostaining of the urine sediment was performed. The analysis revealed several rectangular and irregular casts with intense and bright stain for λ LCs only. A myelogram was performed, showing extensive occupation of the bone marrow by plasma cells; and immunofixation in urine and serum revealed monoclonal IgG-λ component, confirming the diagnosis of IgG-λ MM. This case highlights the potential utility of the urine sediment analysis and immuno-staining as a reliable non-invasive alternative method for diagnosis of cast nephropathy in patients with monoclonal gammopathies.

Background Monoclonal gammopathy of renal significance (MGRS)-related lesions are infrequent entities. There are no publications on these disorders in Latin America (LA). The aim of this study was to describe epidemiological and clinical characteristics of these patients in LA. Methods We performed a multicentre retrospective study. Patients with diagnosis of MGRS between 2012 and 2018 were included. Epidemiological and clinical data were collected from clinical records. Results Twenty-seven patients from Chile, Argentina, Ecuador and Uruguay were included. Half debuted with a nephrotic syndrome, and 32% required dialysis. Proliferative glomerulonephritis with monoclonal immunoglobulin deposits was found in 33%, amyloidosis in 26% and monoclonal immunoglobulin deposition disease also in 26%. The immunoglobulin most frequently found in renal biopsies was IgG kappa. In 67% a paraprotein was found. Twenty patients received an anti-plasma cell regimen, and 3 a rituximab-based regimen (IgM-MGRS). Renal response (RR) was achieved in 56%. Early treatment (≤3 months) was associated with higher RR (75% vs 43%). Three patients relapsed within 21.5 months, and 3 progressed: 1 to multiple myeloma, 1 to systemic amyloidosis and another to systemic light-chain deposition disease. Two patients died, both due to infection during induction treatment. Conclusion There was a higher than expected frequency of patients requiring dialysis. The most common MGRS-related lesion was PGNMD. Early treatment was associated with better response. As a rare disease, increasing awareness and promoting early diagnosis are necessary in LA to improve outcomes. SUMMARY AT A GLANCE A collection of 27 cases of MGRS from Latin America with information on epidemiology, clinical characteristics, treatment and outcome of patients diagnosed of MGRS-related renal lesions.

Granulomatous lobular mastitis is a rare disease whose origin is still unknown and shows an increase in its frequency. Morphological, microbiological, and molecular biology studies have linked this disease to lipophilic and fastidious corynebacteria, suggesting its possible infectious etiology. This series describes and reviews in detail the distinctive morphological characteristics of the bacteria present in the granulomas of this disease, the usefulness of histochemical techniques for their identification, and our proposal for a tissue quantification score for the bacteria. The MacCallum-Goodpasture method of Gram’s stain turned out to be the gold standard for examination, but we also highlight the efficiency of hematoxylin and eosin stain when it is exhaustively examined as well as the Grocott stain to evaluate the bacterial pleomorphism method, which is often underutilized.

ANCA-associated vasculitis (AAV) is an infrequent disease in childhood. International literature about pediatric vasculitis is scarce, and it mainly refers to other systemic vasculitides with a higher incidence in childhood, such as IgA vasculitis and Kawasaki disease.To describe the clini cal and laboratory characteristics of a series of pediatric cases with AAV.Re trospective, descriptive study of patients with diagnosis of AAV treated at a tertiary health center from Santiago, Chile, between 2000 and 2020. Electronic medical records were reviewed collecting epidemiological, laboratory, images, and biopsies data.There were five cases of pediatric pa tients with AAV, with varying degrees of severity, and the age range at the onset was 5.5 to 13.5 years. We observed frequent renal involvement in microscopic polyangiitis (MPA) and eye involvement due to orbital pseudotumor in patients with granulomatosis with polyangiitis (GPA), an infrequent manifestation in the international pediatric literature. Patients were treated according to recommen dations extrapolated from clinical trials in adult populations, showing excellent clinical response to induction therapy with systemic corticosteroids and cyclophosphamide or rituximab. During main tenance therapy, most of the patients were stable on rituximab, azathioprine, or methotrexate. No patient developed organ damage and all cases achieved discontinuation of the corticosteroid therapy.This report describes the clinical characteristics of AAV in a series of pediatric patients. In this series, renal involvement was common in MPA and eye involvement due to orbital pseudotu mor in GPA. The clinical response with treatment according to recommendations extrapolated from the adult population was favorable.

Background Bladder tumors in pregnancy are extremely rare. No more than 50 cases have been published to date, including all histologic variants, and only three cases of bladder squamous cell carcinoma have been described. Case presentation We present a clinical case of a 31-year-old woman with bladder squamous cell carcinoma in the second trimester of pregnancy. After a C-section at 30 weeks, we performed radical cystectomy with extended bilateral lymphadenectomy, hysterectomy and right oophorectomy. The Studer neobladder technique was performed for urinary tract reconstruction. Definitive pathology showed invasive bladder squamous cell carcinoma, Grade 2, with microscopic infiltration of the perivesical fat, negative margins, and 3/28 lymph nodes with carcinoma (pT3aN2M0). The patient underwent 18 months of surveillance after radical cystectomy, without recurrence by PET-CT. Conclusions Bladder cancer in pregnant women is extremely rare but must be considered in those with recurrent gross hematuria and/or recurrent urinary tract infection. To our knowledge, this case involves the longest recurrence-free survival of a pregnant woman with squamous cell bladder cancer published thus far.

Acute phosphate nephropathy (APN) is an acute renal failure secondary to the use of oral sodium phosphate (OSP) laxatives, with a high risk of progression to chronicity. We report a 60-year-old woman with mixed connective tissue disease whose serum creatinine increased up to 2.0 mg/dL in her regular control tests, without an evident causative factor. Kidney biopsy showed numerous intratubular calcium phosphate deposits, consistent with APN. She had a history of OSP laxative intake, and a sodium phosphate enema was used before a colonoscopy performed six months earlier. The temporal association between the use of OSP laxatives and acute kidney injury, should lead to the suspicion of APN. The urine sediment is generally normal or with mild to moderate proteinuria. The diagnosis is confirmed with a kidney biopsy. Until now, there is no specific treatment for APN, thus prevention is essential. In high-risk patients for developing APN, the administration of these laxatives should be avoided.

Both premature birth and low birth weight compromise nephron development. The lower nephron endowment is subjected to compensatory hyperfiltration that overloads the glomeruli and leads to the vicious circle of progressive deterioration of renal function.To emphasize the risk of renal involvement in this susceptible population by describing the case of a patient with long-term follow-up.Low-weight premature newborn, who presented at 3 years of age severe hypertension, which was controlled with different types of antihypertensive drugs. However, 10 years later subnephrotic proteinuria was detected; a renal biopsy confirmed a focal and segmental glome rulosclerosis. Despite blocking the renin-angiotensin system for 23 years, his renal function progres sively deteriorated, until requiring chronic hemodialysis during the last 3 years.It is essential to increase the awareness of the risk of renal damage in premature and low weight newborns in order to establish management that covers from gestation to adult life and to achieve an individual and epidemiological impact on renal health.

One of the devastating consequences of monoclonal gammopathies is the development of end-stage kidney disease, which can be prevented with an early diagnosis. Renal involvement can be secondary to saturation of paraproteins with intratubular precipitation or the glomerular deposition of paraproteins with secondary inflammation and destruction. These conditions can also be associated with monoclonal gammopathies that do not meet hematological treatment criteria, called monoclonal gammopathies of renal significance (MGRS).To report a retrospective analysis of patients who underwent a renal biopsy and whose final diagnosis was a form of monoclonal gammopathy.We reviewed the clinical and laboratory features and response to treatment of 22 patients aged 63 ± 12 years (55% women) with a pathological diagnosis of a nephropathy associated with paraproteinemia.The most common hematological diagnosis was amyloidosis in 50% of patients, followed by cast nephropathy. The predominant clinical presentations were proteinuria (without nephrotic syndrome) and nephritic syndrome. Classic criteria such as erythrocyte sedimentation rate100 mm/h and protein-albumin gap were unusual. Serum light chain quantification was the test with the best yield to detect paraproteins.In this group of patients, light chains tend to affect the kidney more commonly than heavy chains. The prognosis of multiple myeloma is much worse than MGRS.

Lupus nephritis (LN) is one of the most serious manifestations of systemic lupus erythematosus (SLE). Based on studies showing the potential role of heme oxygenase-1 (HO-1), an enzyme that catalyzes the degradation of heme and has anti-inflammatory properties in SLE development, we decided to explore HO-1 in LN. Accordingly, we evaluated HO-1 levels and function in circulating and infiltrating monocytes and neutrophils of LN patients. HO-1 levels were assessed in peripheral monocytes of LN patients and controls by flow cytometry and immunofluorescence microscopy. Phagocytosis and the production of reactive oxygen species (ROS) were evaluated to determine the effect of HO-1 in monocyte function. In addition, renal biopsies with proliferative LN were used to identify HO-1 in infiltrating cells and renal tissue by immunofluorescence and immunohistochemistry. Biopsies of healthy controls (HC) and patients who underwent nephrectomy were included as controls. Circulating pro-inflammatory monocytes and activated neutrophils were increased in LN patients. HO-1 levels were decreased in all subsets of monocytes and in activated neutrophils. LN monocytes showed increased phagocytosis and higher production of ROS than those of HC. When HO-1 was induced, phagocytosis and ROS levels became similar to those of HC. HO-1 was mostly expressed in renal tubular epithelial cells (RTEC). Renal tissue of LN patients showed lower levels of HO-1 than HC, whereas infiltrating immune cells of LN showed lower levels of HO-1 than biopsies of patients who had renal surgery. HO-1 is decreased in circulating monocytes and activated neutrophils of LN patients. HO-1 levels modulate the phagocytosis of LN monocytes and ROS production. HO-1 expression in RTEC might be an attempt of self-protection from inflammation.

C1q nephropathy is a rare glomerulopathy characterized by mesangial deposition of the complement component C1q. These deposits can be isolated or associated with immunoglobulins or complement fractions, which are observed by immunofluorescence or immunohistochemical microscopy. In ultramicroscopy, dense mesangial deposits and alterations of the podocyte are observed. Clinically it presents as a nephrotic syndrome (NS) or by alterations of the urinalysis such as proteinuria and/or hematuria in children and young adults. In light microscopy, it is expressed with a morphological pattern of minimal change disease (MCD), mesangial proliferative glomerulonephritis or focal segmental glomerulosclerosis (FSGS). The NS during its evolution usually evolve in steroid resistance or steroid dependency, often requiring the association of immunosuppressants to obtain remission. We report a 14 years old male with a history of NS and its evolution under various treatments during a 12-year follow-up.

Goodpasture Syndrome is described as a single episode disease entity. It is diagnosed with the demonstration of antiglomerular basement (anti-GBM) antibodies in plasma or renal tissue. Although the recurrence of anti-GBM disease is rare, it has been reported in up to 3% of cases. Recurrence with negative anti-GBM antibodies in plasma is even less frequent We report a 63 years old male in whom anti-GBM disease recurred without detectable anti-GBM antibodies in plasma, despite having positive antibodies at the onset.

Background Lupus nephritis (LN) is a complication of systemic lupus erythematosus that requires renal biopsy (RB). Proliferative classes III, IV-S, IV-G have especial clinical and pathological characteristics. Aim To determine the association between pathological features in RB with serum creatinine and urine protein levels. Material and Methods We analyzed 186 RB performed in adults aged 18 to 73 years, from a renal pathology reference center. Histopathological variables such as class and subclass of proliferative LN, endocapillary and extracapillary proliferation, activity and chronicity indexes, and vascular sclerosis were correlated with serum creatinine and urine protein levels, at the time of diagnosis. Results As compared with LN III, all the morphological and laboratory values were significantly more deteriorated in LN IV, with special focus on vascular sclerosis. Serum creatinine was the only variable that significantly differentiated LN IV-S from LN IV-G. Proteinuria was non-significantly higher in LN IV-G compared to LN IV-S. However, the difference became significant when proteinuria was compared between LN IV-G and LN III. Conclusions The significant difference in serum creatinine between LN IV-S and LN IV-G supports the concept that they are different subclasses. Proteinuria is a variable that differentiates classes III from IV-G, being significantly higher in the second. Severe arteriosclerosis is a constant and significant finding that differentiates LN III from LN IV. Thus, we propose its usefulness for distinguishing LN classes, and eventually, to be considered in the chronicity index.

We report a 23 year old woman presenting with a nephrotic syndrome due to minimal change disease, central diabetes insipidus, primary hypothyroidism, vitiligo and universal alopecia. Eleven years later, she presented secondary amenorrhea due to hypogonadotropic hypogonadism, with mild hyperprolactinemia and central adrenal insufficiency. A magnetic resonance imaging of the sella turcica showed a pituitary mass with suprasellar extension that was resected using a transsphenoidal approach. Pathology confirmed the presence of a lymphoplasmacytic hypophysitis. She needed a second surgical resection due to mass growth and neuro-ophthalmologic impairment. One year later, systemic lupus erythematosus, arterial hypertension and type 2 diabetes mellitus were diagnosed. Two years later, due to back pain, constipation and renal failure, retroperitoneal fibrosis was found, satisfactorily treated with glucocorticoids and colchicine. Hence, this clinical vignette shows the coexistence of autoimmune polyglandular syndrome with retroperitoneal fibrosis and lymphoplasmacytic hypophysitis. Tissue analysis showed the presence of IgG4 producing plasma cells in the pituitary and retroperitoneum, which constitute a basis for the diagnosis of IgG4 related disease.

Renal involvement is a frequent complication in antineutrophil cytoplasmic antibodies (ANCA)associated vasculitides, adding morbidity and mortality, such as chronic kidney disease and the need for renal replacement therapy. With the aim of reaching a consensus on relevant issues regarding the diagnosis, treatment and follow-up of patients with these diseases, the Chilean Societies of Nephrology and Rheumatology formed a working group that, based on a critical review of the available literature and their experience, raised and answered consensually a set of questions relevant to the subject. This document includes aspects related to the clinical diagnosis, the histological characteristics, the therapeutic alternatives to induce and maintain the remission of the disease, relapse surveillance strategies and complementary therapies.

ANCA mediated vasculitis mainly occur between the fourth and fifth decade of life; therefore, it is very uncommon to see pregnant patients with the disease. Vasculitis may affect significantly the course of pregnancy; in turn pregnancy can change the course of vasculitis. We report a 20 years old woman with ANCA-mediated renal vasculitis lasting 10 years who consulted with a pregnancy of 15 weeks. She was in remission and had amenorrhea attributed to ovarian toxicity due to cyclophosphamide. Pregnancy had an uneventful course with spontaneous delivery at the 37th week, giving birth to a healthy newborn. Proteinuria increased during the course of pregnancy with a mild deterioration of kidney function. During the year after delivery, she had nephrotic proteinuria and a worsening of renal function.

HIV infection has different clinical presentations. We report a 21-year-old male with longstanding isolated microscopic hematuria attributed to thin glomerular basement membrane disease, who after 15 years of follow-up presented with significant proteinuria. A kidney biopsy was performed, revealing the presence of tubulo-reticular inclusions in the glomerular endothelial cells. This finding led to suspect an HIV infection, which was verified. Antiretroviral therapy, angiotensin-converting enzyme and angiotensin II receptor blockers were prescribed. At 6 years of diagnosis the patient is asymptomatic and has normal kidney function. Microscopic hematuria and low level proteinuria persists.

A 31-year-old woman with nephronophthisis received a cadaveric kidney transplant, and was immunosuppressed with cyclosporine, azathioprine and steroids. Twelve days after transplant a biopsy showed acute rejection with vascular damage. She was treated with 3 pulses of methylprednisolone and change of immunosuppression to mycophenolate mofetil and tacrolimus, without improving graft function. At day 21, a second biopsy showed accentuation of interstitial and vascular rejection. Antibody-mediated rejection was suspected and plasmapheresis and rituximab were prescribed. Graft function improved rapidly. Staining for C4d was negative and there were no circulating antibodies against the donor. In the interstitial infiltrate there were clusters of B lymphocytes that accounted for 40% of cells, which was thought to be an ominous sign, as it has been associated with poor graft outcome. Acute T-cell-mediated rejection grade III (Banff 07) was diagnosed. Thirty-nine months after transplant her kidney function is stable with no other complication. This clinical case generates the hypothesis that rituximab may have a beneficial role in the therapy of acute cellular rejection when there are clusters of B lymphocytes in the infiltrate and a good response has not been obtained to conventional anti-rejection therapy.

Paraneoplastic syndromes can be presented in multiple ways, which include endocrinological, hematologic, rheumatologic and nephrologic manifestations. While most of the publications described solid tumors as responsible for these manifestations, hematologic neoplasms are important cause to consider as part of the differential diagnosis. We report the case of a 46 year-old man with seronegative symmetric polyarthritis of large and small joints associated with membranoproliferative glomerulonephritis with deposits of immune complexes and acute impairment of renal function, as part of a paraneoplastic syndrome secondary of a classical Hodgkin lymphoma with bone marrow invasion, which reversed completely with chemotherapy treatment.

Gemcitabine is a widely used drug in the treatment of advanced pancreatic cancer and other malignancies. It is generally well tolerated and exceptionally its use has been associated with hemolytic-uremic syndrome, causing acute kidney injury, hypertension, chronic renal failure requiring dialysis, and death. We report a 60-year-old man with pancreatic carcinoma and regional lymph node invasion, whom after four months of therapy with gemcitabine and after dose number 11, suddenly developed an acute nephritic syndrome with moderate renal impairment, associated with severe anemia (hemoglobin 6.0 g/dL) and thrombocytopenia (20,000 mm³). Renal biopsy showed the classic findings of thrombotic microangiopathy Gemcitabine was discontinued and renal function and hematological parameters gradually improved.

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used by patients all over the world. Five to eighteen percent of the patients who receive NSAIDs can suffer from kidney-related side effects. Among them, the most relevant are sodium and water retention, hyponatremia, worsening of hypertension or preexisting cardiac failure, hyperkalemia, acute kidney injury, chronic kidney disease, papillary necrosis, nephrotic syndrome (NS), and acute interstitial nephritis. We report the case of a 65-year-old woman who developed acute tubular necrosis and NS a few days after receiving 15 mg of meloxicam (MLX) for 3 days for tendinitis. Steroid therapy was begun with normalization of kidney function after 7 weeks of treatment. NS (minimal change disease) was characterized by frequent remissions and relapses as prednisone was lowered under 30 mg/day. Azathioprine (100 mg/day) was added on the fifth month of diagnosis and a complete remission was finally obtained 4 years after hospital admittance. In her last medical checkup, 8 years after her debut and receiving azathioprine (50 mg) and prednisone (5 mg/day), renal function was normal (creatinine 1.0 mg/dL and creatinine clearance 80 mL/min/1.73 m(2)), proteinuria was 150 mg/day and there was no hematuria or hypertension. The aim of communicating this case is to raise a warning about these renal side effects of MLX. After thorough review of literature, only one other report with the same findings was found.

Nephrotic syndrome secondary to paraneoplastic glomerulopathies is exceptional. We are aware of only three cases reported of cervical carcinomas associated with nephrotic syndrome. Two women, aged 40 and 79 years, presented with nephrotic syndrome. The first had a membranous nephropathy and the second was not biopsied. The first women had a metrorrhagia after 8 months of unsuccessful therapy with corticosteroids and immunosuppressive drugs. An advanced cervical carcinoma with lymph node metastases was found. In the second patient, a cervical carcinoma and hematometra was discovered two months after diagnosis ofa nephrotic syndrome. The syndrome subsided completely, nine months after radiotherapy and chemotherapy in the first patient and 10 months after hysterectomy in the second patient.

Collapsing glomerulopathy is a form of focal segmental glomerulosclerosis that is usually associated with HIV-1 infection, and is characterized by its poor prognosis and almost inevitable progression to end-stage renal disease. Its pathological features include collapsed glomeruli, podocyte hypertrophy and hyperplasia, and pseudocrescents. This case report shows the evolution of a 58-year-old patient with non-HIV idiopathic collapsing glomerulopathy who presented with severe nephrotic syndrome and renal insufficiency and was treated with lisinopril and deflazacort, a synthetic corticosteroid that has shown fewer cosmetic effects and glucose and bone metabolism complications than prednisone. The patient responded with full recovery of renal function and normal range of protein excreted in urine after less than two years of treatment. The patient has not suffered a recurrence of his nephrotic syndrome after three years of steroid withdrawal. There is no proven therapy for collapsing glomerulopathy, and this case highlights an alternative for treating this disease with few secondary effects.