Catastrophic antiphospholipid syndrome: Lessons from the "CAPS Registry".

The catastrophic antiphospholipid syndrome (CAPS) is a rare life-threatening clinical condition that represents the most severe clinical presentation of the antiphospholipid syndrome (APS). It was first described in 1992 in a group of patients that presented with multiorgan involvement and microangiopathic features of APS. Most of the current knowledge of CAPS comes from the analysis of all cases collected at the "CAPS Registry" that was created in 2000 to perform studies on this condition. Most cases are triggered by a prothrombotic situation that leads to a multiorgan thrombosis and a cytokine storm. The analysis of cases included in the "CAPS Registry" has shown that the triple therapy with anticoagulation, glucocorticoids, and plasma exchange and/or intravenous immunoglobulins is associated to a better prognosis of CAPS. The improvement of the knowledge allowed a decrease from the 50% mortality rate reported in the first series to 25-30% in the most recent publications.

Immune thrombotic thrombocytopenic purpura: clinical suspicion and basic management in emergency departments - an expert review and consensus statement from the Spanish societies of hematology and hemotherapy (SEHH) and emergency medicine (SEMES). / Púrpura trombocitopénica trombótica inmune: sospecha y manejo básico en los servicios de urgencias. Revisión y consenso de un grupo de expertos de las sociedades científicas SEHH y SEMES.

TEXT: Acquired or immune thrombotic thrombocytopenic purpura (TTP) are thrombotic microangiopathies associated with high mortality if treatment is not started early. Onset is usually sudden, meaning that the condition is often diagnosed in hospital emergency departments, where TTP must be suspected as early as possible. These guidelines were drafted by specialists in emergency medicine and hematology to cover the diagnosis, referral, and treatment of patients suspected of immune-mediated TTP who require emergency care. Immune TTP should be suspected whenever a patient presents with hemolytic microangiopathy and has a negative Coombs test, and thrombocytopenia, possibly in conjunction with fever and neurologic and cardiac alterations. If one of the existing diagnostic algorithms indicates there is a high probability that the patient has immune TTP, plasma exchange therapy should be started along with immunosuppressants. Treatment with caplacizumab should also be considered. The patient should be referred immediately to the hematology department within the same hospital or a referral hospital.

TEXTO: La púrpura trombótica trombocitopénica adquirida o inmune (PTTi) es una microangiopatía trombótica (MAT) con una elevada mortalidad si no se instaura un tratamiento precoz. El inicio habitualmente brusco de la enfermedad hace que, en la mayoría de los pacientes, el diagnóstico inicial se haga en los servicios de urgencias hospitalarios (SUH), donde se debe sospechar esta entidad con la mayor inmediatez posible. Esta guía, elaborada por profesionales de Medicina de Urgencias y de Hematología, establece unas recomendaciones en cuanto al diagnóstico, derivación y tratamiento de los pacientes con sospecha de PTTi en los SUH. Se debe sospechar PTTi en todo paciente que presente una anemia hemolítica microangiopática, prueba de Coombs directo negativa y trombocitopenia pudiendo asociar, además, fiebre, alteraciones neurológicas y cardiacas. Si tras la aplicación de alguno de los algoritmos diagnósticos existentes, hay una alta probabilidad de que el paciente presente una PTTi, debería iniciarse tratamiento con recambio plasmático, inmunosupresores y valorar el inicio de caplacizumab. Además, debe gestionarse el traslado inmediato de los pacientes al Servicio de Hematología, bien del mismo centro o a uno de referencia.

Thrombotic microangiopathies in critically ill children: The MATUCIP registry in Spain.

INTRODUCTION: Thrombotic microangiopathies (TMA) are rare diseases usually presenting with renal, haematological, neurologic and cardiovascular involvement and nonspecific but severe symptoms. A registry of TMA cases managed in Spanish paediatric intensive care units (the MATUCIP Registry) was established with the aim of gaining knowledge on their clinical characteristics, diagnosis and acute-phase treatment. METHODS: We conducted a prospective multicentre observational study in 20 paediatric intensive care units (PICUs) in Spain from January 2017 to December 2021 in children aged more than 1 month with TMAs, who were followed up through the discharge from the PICU. RESULTS: The sample included 97 patients (51.5% female) with a median age of 2.6 years (interquartile range [IQR], 1.6-5.7). The initial manifestations were gastrointestinal (74.2%), respiratory (14.4%), fever (5.2%), neurologic (3.1%) and other (3.1%). At admission, 75.3% of patients had microangiopathic haemolytic anaemia, 95.9% thrombocytopenia and 94.8% acute kidney injury. Of the total sample, 57.7% of patients received a diagnosis of Shiga toxin-associated haemolytic uraemic syndrome (HUS), 14.4% of Streptococcus pneumoniae-associated HUS, 15.6% of atypical HUS, 10.3% of secondary TMA and 2.1% of thrombotic thrombocytopenic purpura. Eighty-seven patients (89.7%) developed arterial hypertension, and 49.5% gastrointestinal, 22.7% respiratory, 25.8% neurologic and 12.4% cardiac manifestations. Also, 60.8% required renal replacement therapy and 2.1% plasma exchange. Twenty patients received eculizumab. The median PICU stay was 8.5 days (IQR, 5-16.5). Two children died. CONCLUSIONS: The MATUCIP registry demonstrates the clinical variability of TMA cases requiring admission to the PICU. Knowledge of the presentation and outcomes of TMAs can facilitate early aetiological diagnosis. This registry can help improve our understanding of the clinical spectrum of these diseases, for which there is a dearth of published data.

Management of atypical uremic hemolytic syndrome in pregnant patient.

Atypical uremic haemolytic syndrome is a variant of thrombotic micro-andiopathy characterized by non-autoimmune hemolytic anemia, thrombocytopenia and acute renal failure as a result of excessive activation of the complement. Up to 60% of patients have mutations in the genes that encode the complement system. A disensing factor is required for its manifestation, including gestation. It is an entity with a high morbidity, which can decrease drastically if an early diagnosis is made and appropriate treatment is initiated. Administration of ecuilizumab has demonstrated rapid process disruption, reducing the need for extrarenal purification therapies and improving renal function and patient prognosis.

Nephrotic syndrome as a manifestation of thrombotic microangiopathy due to long-term use of sunitinib.

Nephrotic syndrome in patients with cancer may be related to the primary malignancy or chemotherapeutic therapy. Solid organ cancers may cause membranous glomerulonephritis which is manifested by nephrotic syndrome; other less common histologic presentations include focal and segmental glomerulosclerosis and minimal change disease. In addition, chemotherapy agents may cause renal toxicity by affecting the small blood vessels, glomeruli, tubules, and interstitium. Tyrosine kinase inhibitors such as sunitinib may cause endothelial and podocyte damage leading to thrombotic microangiopathy affecting only the kidney and manifested by proteinuria and hypertension. We report a case of an elderly man with gastrointestinal stromal tumor (GIST) on treatment with sunitinib who had as a complication a thrombotic microangiopathy manifested with nephrotic syndrome and a hypertension of difficult control, which was finally controlled by stopping this drug but had a fatal outcome due to its malignancy.

Diagnostic-therapeutic algorithm for thrombotic microangiopathy. A report of two cases.

Thrombotic microangiopathies (TMA) are a group of clinical syndromes associated with haemolytic anaemia, thrombocytopenia and organ dysfunction, mainly renal or neurological. They are associated with significant morbidity and mortality, so early diagnosis and treatment are essential. In this article we report two cases of TMA; a patient with thrombotic thrombocytopenic purpura (TTP) and a patient with atypical haemolytic uraemic syndrome (aHUS).

Recommendations for the diagnosis and treatment of patients with thrombotic thrombocytopenic purpura. / Recomendaciones para el abordaje clínico de pacientes con púrpura trombocitopénica trombótica.

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy (TMA) characterized by the development of microangiopathic haemolytic anaemia, thrombocytopenia, and ischaemic organ dysfunction associated with ADAMTS13 levels lower than 10% in most cases. Recently there have been numerous advances in the field of PTT, new, rapid and accessible techniques capable of quantifying ADAMTS13 activity and inhibitors. The massive sequencing systems facilitate the identification of polymorphisms in the ADAMTS13 gene. In addition, new drugs such as caplacizumab have appeared and relapse prevention strategies are being proposed with the use of rituximab. The existence of TTP patient registries allow a deeper understanding of this disease but the great variability in the diagnosis and treatment makes it necessary to elaborate guidelines that homogenize terminology and clinical practice. The recommendations set out in this document were prepared following the AGREE methodology. The research questions were formulated according to the PICO format. A search of the literature published during the last 10 years was carried out. The recommendations were established by consensus among the entire group, specifying the existing strengths and limitations according to the level of evidence obtained. In conclusion, this document contains recommendations on the management, diagnosis, and treatment of TTP with the ultimate objective of developing guidelines based on the evidence published to date that allow healthcare professionals to optimize TTP treatment.

Clínica neurológica fluctuante: ¿Llamo al neurólogo o al hematólogo?

Objetivos: Resaltar el papel del laboratorio clínico y la pronta comunicación con el servicio de Hematología en el diagnóstico y la rapidez en la instauración del tratamiento de una patología hematológica tan urgente como la Púrpura Trombótica Trombocitopénica (PTT). Caso clínico: Varón de edad avanzada derivado a Urgencias hospitalarias por su médico de Atención Primaria por trastorno de emisión del lenguaje, asimetría facial y disminución de fuerza en extremidad superior, por lo que se activa el código ictus. Sin embargo, los hallazgos de laboratorio (anemia y trombocitopenia, creatinina, bilirrubina total y LDH elevadas, test de Coombs directo negativo) y presencia de esquistocitos en el frotis de sangre periférica, acaban derivando en un diagnóstico completamente diferente: microangiopatía trombótica tipo PTT. Conclusiones: La primera orientación diagnóstica de ictus hemisférico izquierdo fue rechazada ante los signos de anemia hemolítica no autoinmune, trombocitopenia sin causa aparente y presencia de esquistocitos. No debemos olvidar que esta patología puede cursar con afectación multiorgánica y características clínicas muy variables. Aunque su diagnóstico definitivo se basa en la determinación de actividad de ADAMTS-13, debido a la elevada mortalidad es necesario instaurar tratamiento de forma inmediata tras su sospecha.

Nephrotic syndrome as a manifestation of thrombotic microangiopathy due to long-term use of sunitinib. / Síndrome nefrótico como manifestación de microangiopatía trombótica secundaria al uso crónico de sunitinib.

Nephrotic syndrome in patients with cancer may be related to the primary malignancy or chemotherapeutic therapy. Solid organ cancers may cause membranous glomerulonephritis manifesting with nephrotic syndrome; other less common histologic presentations include focal and segmental glomerulosclerosis and minimal change disease. In addition, chemotherapy agents can cause renal toxicity by affecting the small blood vessels, glomeruli, tubules, and interstitium. Tyrosine kinase inhibitors such as sunitinib may cause endothelial and podocyte damage leading to renal limited thrombotic microangiopathy, manifested by proteinuria and hypertension. We report a case of an elderly man with gastrointestinal stromal tumor (GIST) on treatment with sunitinib who had as a complication of a thrombotic microangiopathy manifested with nephrotic syndrome and difficult-to-control hypertension, which was controlled by stopping this drug but with a fatal outcome due to its malignant neoplasm.

Management of atypical uremic hemolytic syndrome in pregnant patient. / Manejo de síndrome hemolítico urémico atípico en la paciente gestante.

Atypical uremic haemolytic syndrome is a variant of thrombotic micro-andiopathy characterized by non-autoimmune hemolytic anemia, thrombocytopenia and acute renal failure as a result of excessive activation of the complement. Up to 60% of patients have mutations in the genes that encode the complement system. A disensing factor is required for its manifestation, including gestation. It is an entity with a high morbidity, which can decrease drastically if an early diagnosis is made and appropriate treatment is initiated. Administration of ecuilizumab has demonstrated rapid process disruption, reducing the need for extrarenal purification therapies and improving renal function and patient prognosis.

Diagnostic-therapeutic algorithm for thrombotic microangiopathy. A report of two cases. / Algoritmo diagnóstico-terapéutico de las microangiopatías trombóticas. A propósito de 2 casos.

Thrombotic microangiopathies (TMA) are a group of clinical syndromes associated with haemolytic anaemia, thrombocytopenia and organ dysfunction, mainly renal or neurological. They are associated with significant morbidity and mortality, so early diagnosis and treatment are essential. In this article we report two cases of TMA; a patient with thrombotic thrombocytopenic purpura (TTP) and a patient with atypical haemolytic uraemic syndrome (aHUS).

Ischemic-hemorrhagic stroke in patients with Covid-19. / Afectación cerebrovascular isquémico-hemorrágica en pacientes con covid-19.

Coronavirus associated severe acute respiratory syndrome (SARS-CoV-2) causes a worldwide syndrome called Covid-19 that has caused 5,940,441 infections and 362,813 deaths until May 2020. In moderate and severe stages of the infection a generalized swelling, cytokine storm and an increment of the heart damage biomarkers occur. In addition, a relation between Covid-19 and neurological symptoms have been suggested. The results of autopsies suggest thrombotic microangiopathy in multiple organs. We present 2 cases of patients infected with severe Covid-19 that were hospitalized in the Reanimation Unit that presented cerebrovascular symptoms and died afterwards. A high dose prophylaxis with antithrombotic medication is recommended in patients affected by moderate to severe Covid-19.

Nefropatía por IgA con microangiopatía trombótica / IgA nephropathy with thrombotic microangiopathy

INTRODUCTION: IgA nephropathy is the most common glomerulopathy in the world, it has a wide clinical expression, from asymptomatic to rapidly progressive glomerulonephritis. The definitive diagnosis is renal biopsy, within which the IgA pattern can be identified, including thrombotic microangiopathy. CLINICAL CASE: 28-year-old female patient, with a history of preeclampsia in the last pregnancy, presents high blood pressure, hematuria and proteinuria. Study begins with initially negative results. Renal biopsy confirms IgA nephropathy with thrombotic microangiopathy. DISCUSSION: Vascular damage is underestimated in IgA nephropathy. Thrombotic microangiopathy can be associated with various clinical manifestations, however when it is associated with IgA Nephropathy it is usually associated with proteinuria, arterial hypertension and elevation of creatinine. In the presence of microangiopathy, secondary causes must be ruled out. In general, there is no pathognomonic serological marker. Eventually patients could benefit from the use of eculizumab. CONCLUSION: IgA nephropathy is the most common glomerulopathy worldwide; there is a wide range of clinical presentations, among which thrombotic microangiopathy can be found. This presentation is associated with a higher risk of progression to end-stage renal disease.

INTRODUCCIÓN: La nefropatía por IgA es la glomerulopatía más frecuente en el mundo, tiene una amplia expresión clínica, desde asintomática hasta glomerulonefritis rápidamente progresivas. El diagnóstico definitivo es la biopsia renal, dentro de las cuales se puede identificar el patrón de la IgA, dentro de los cuales está la microangiopatía trombótica. CASO CLÍNICO: Paciente femenina 28 años, con antecedentes de preeclampsia en último embarazo, presenta hipertensión arterial, hematuria y proteinuria. Se inicia estudio con resultados inicialmente negativos. Biopsia renal confirma nefropatía por IgA con microangiopatía trombótica. DISCUSIÓN: En la nefropatía por IgA se subestima el daño vascular. La microangiopatía trombótica se puede asociar con varias manifestaciones clínicas, sin embargo, cuando está asociada a NIgA suele estar asociado con proteinuria, hipertensión arterial y elevación y creatinina. Ante la presencia de microangiopatía, se deben descartar causas secundarias de la misma. En general no existe un marcador serológico patognomónico. Eventualmente los pacientes se podrían beneficiar del uso de eculizumab. CONCLUSIÓN: La nefropatía por IgA es la glomerulopatía más frecuente a nivel mundial, existe una gran gama de presentaciones clínicas, dentro de las cuales se puede encontrar microangiopatía trombótica. Esta última presentación se asocia con mayor riesgo de progresión a enfermedad renal en etapa terminal.

Near-fatal cocaine intoxication in an infant with thrombotic microangiopathy associated with multiple organ failure / Intoxicação grave por cocaína em criança com microangiopatia trombótica associada à falência múltipla de órgãos

ABSTRACT Objective: To report a pediatric case of drug-induced thrombotic microangiopathy caused by cocaine Case description: We report a nine-month-old patient who developed thrombotic microangiopathies after extreme cocaine intoxication, multiple organ dysfunction syndrome with hemodynamic dysfunction, anuric renal failure, liver failure, encephalopathy, and myocardial injury, corresponding phenotypically to thrombocytopenia-associated multiple organ failure. The patient received continuous venous hemofiltration and therapeutic plasma exchange, recovering satisfactorily. She was discharged after 30 days of hospitalization under the guidance of the childcare service, and was healthy after one year of follow-up. Toxicological samples confirmed high levels of cocaine and derivatives in blood, urine and hair. Comments: To our knowledge, this is the first reported pediatric case. There are particularities of cocaine intoxication pathophysiology that can trigger thrombotic microangiopathies because of vasoconstriction, direct endothelial injury, platelet activation, and increasing von Willebrand factor and fibrinogen levels. All of which results in a prothrombotic state, inflammatory dysregulation, and microvascular thrombi. The increasing use of cocaine, especially among young adults, puts children at high risk of toxicity, either by passive unintentional exposure, or abuse due to the increased availability in homes.

RESUMO Objetivo: Relatar um caso pediátrico de microangiopatia trombótica induzida por drogas causada por cocaína Descrição do caso: Relatamos uma paciente de nove meses de idade que desenvolveu microangiopatia trombótica após intoxicação extrema por cocaína, síndrome de disfunção de múltiplos órgãos com disfunção hemodinâmica, insuficiência renal anúrica, insuficiência hepática, encefalopatia e lesão miocárdica, correspondendo fenotipicamente à falência múltipla de órgãos associada à trombocitopenia. A paciente recebeu hemofiltração venosa contínua e plasmaférese terapêutica, recuperando-se satisfatoriamente. Recebeu alta após 30 dias de internação sob orientação do serviço de puericultura e estava saudável após um ano de seguimento. Amostras toxicológicas confirmaram altos níveis de cocaína e derivados no sangue, urina e cabelos. Comentários: Até onde sabemos, este é o primeiro caso pediátrico relatado. Existem particularidades da fisiopatologia da intoxicação por cocaína que podem desencadear a microangiopatia trombótica devido à vasoconstrição, lesão endotelial direta, ativação plaquetária e aumento do fator de von Willebrand e dos níveis de fibrinogênio. Tudo isso resulta em um estado pró-trombótico, desregulação inflamatória e trombos microvasculares. O uso crescente de cocaína, principalmente entre adultos jovens, coloca as crianças em alto risco de toxicidade, seja por exposição passiva não intencional ou abuso devido à maior disponibilidade nas residências.

Practice guidelines for the emergency treatment of thrombotic microangiopathy. / Guía práctica de tratamiento urgente de la microangiopatía trombótica.

BACKGROUND AND AIM: The term thrombotic microangiopathy (TMA) involves a heterogeneous group of diseases that can be overwhelming or invalidating, with an acute development, characterised by microangiopathic haemolytic anaemia and thrombocytopaenia. Its management during its initial hours is essential to improving the prognostic of these patients. The aim of this review is to give recommendations about the optimisation of TMA initial treatment and to accelerate the aetiological diagnosis. PATIENTS AND METHODS: We provide a practice guideline based on four steps for the initial management of TMA: diagnosis of suspicion, syndromic confirmation, emergent treatment and complementary tests. RESULTS: The detection of microangiopathic haemolytic anaemia (characterised by elevated reticulocytes, LDH and indirect bilirubin, negative direct Coombs test and schistocytes in peripheral blood), and thrombocytopaenia not explained by other secondary aetiologies confirm the syndromic diagnosis of microangiopathic haemolytic anaemia and thrombocytopaenia (MAHAT). These patients require admission to an Intensive Care Unit to initiate plasma exchange therapy as soon as possible, ideally within the first 4-8hours. Prior to this, samples for ADAMTS13 and complement study should be obtained. Finally, it is important to request the complementary tests necessary to have a correct aetiological diagnosis. CONCLUSIONS: Adherence to the agreed recommendations in this guideline will improve therapeutic results by facilitating cooperation between different specialists involved in TMA management.

Microangiopatías trombóticas en niños críticamente enfermos. Registro español MATUCIP / Thrombotic microangiopathies in critically ill children: The MATUCIP registry in Spain

Introducción: Las microangiopatías trombóticas (MAT) son entidades infrecuentes que suelen causar afectación renal, hematológica, neurológica y cardiovascular, con síntomas inespecíficos pero graves. Con la finalidad de mejorar el conocimiento de sus características clínicas, el proceso diagnóstico y el tratamiento en la fase aguda, se ha creado el registro de MAT en las unidades de cuidados intensivos pediátricos (UCIP) de España (Registro MATUCIP). Pacientes y métodos: Estudio observacional, multicéntrico, realizado en 20 UCIP españolas desde enero de 2017 hasta diciembre de 2021 que incluyó niños mayores de 1mes con diagnóstico de MAT y seguimiento hasta el alta de la UCIP. Resultados: Se incluyeron 97 pacientes (51,5% mujeres), con una mediana de edad de 2,6años (RIQ: 1,6-5,7). La clínica inicial fue de tipo gastrointestinal (74,2%), respiratoria (14,4%), cuadro febril (5,2%), neurológica (3,1%) y otras (3,1%). Al ingreso, el 75,3% presentaban anemia hemolítica microangiopática, el 95,9% trombocitopenia y el 94,8% daño renal agudo. Fueron diagnosticados de síndrome hemolítico urémico (SHU) asociado a Escherichia coli productora de toxina Shiga el 57,7%, SHU por Streptococcus pneumoniae el 14,4%, SHU atípico el 15,6%, MAT secundaria el 10,3% y púrpura trombótica trombocitopénica el 2,1%. Desarrollaron hipertensión arterial el 89,7%, manifestaciones digestivas el 49,5%, respiratorias el 22,7%, neurológicas el 25,8% y cardiacas el 12,4%. El 60,8% requirieron depuración extrarrenal y el 2,1%, plasmaféresis. Recibieron eculizumab 20 pacientes. La mediana de estancia en la UCIP fue de 8,5días (RIQ: 5-16,5). Dos niños fallecieron. (AU)

Introduction: Thrombotic microangiopathies (TMA) are rare diseases usually presenting with renal, haematological, neurologic and cardiovascular involvement and nonspecific but severe symptoms. A registry of TMA cases managed in Spanish paediatric intensive care units (the MATUCIP registry) was established with the aim of gaining knowledge on their clinical characteristics, diagnosis and acute-phase treatment. Patients and methods: We conducted a prospective multicentre observational study in 20 paediatric intensive care units (PICUs) in Spain from January 2017 to December 2021 in children aged more than 1month with TMAs, who were followed up through the discharge from the PICU. Results: The sample included 97 patients (51.5% female) with a median age of 2.6years (interquartile range [IQR]: 1.6-5.7). The initial manifestations were gastrointestinal (74.2%), respiratory (14.4%), fever (5.2%), neurologic (3.1%) and other (3.1%). At admission, 75.3% of patients had microangiopathic haemolytic anaemia, 95.9% thrombocytopenia and 94.8% acute kidney injury. Of the total sample, 57.7% of patients received a diagnosis of Shiga toxin-associated haemolytic uraemic syndrome (HUS), 14.4% of Streptococcus pneumoniae-associated HUS, 15.6% of atypical HUS, 10.3% of secondary TMA and 2.1% of thrombotic thrombocytopenic purpura. Eighty-seven patients (89.7%) developed arterial hypertension, and 49.5% gastrointestinal, 22.7% respiratory, 25.8% neurologic and 12.4% cardiac manifestations. Also, 60.8% required renal replacement therapy and 2.1% plasma exchange. Twenty patients received eculizumab. The median PICU stay was 8.5days (IQR: 5-16.5). Two children died. (AU)

Purtscher-like retinopathy associated with dermatomyositis and hemophagocytic lymphohistiocytosis. / Retinopatía Purtscher-like asociada a dermatomiositis y linfohistiocitosis hemofagocítica.

CASE REPORT: An 11 year-old girl with progressive muscle weakness due to dermatomyositis and hemophagocytic lymphohistiocytosis in which multiple cotton exudates, venous tortuosity and flame haemorrhages are detected in the funduscopic examination, leading to the diagnosis of Purtscher-like retinopathy. DISCUSSION: Purstcher's retinopathy is a microvascular disorder with clinical signs of probable thrombotic origin. Its treatment is controversial, with systemic corticosteroids being the most widespread choice.

[The pathology of renal transplants]. / Anatomía patológica del trasplante renal.

In order to make an objective assessment of the histopathology of a renal biopsy during a kidney transplant, all the various elements involved in the process must be understood. It is important to know the characteristics of the donor organ, especially if the donor is older than 65. The histopathological features of the donor biopsy, especially its vascular status, are often related to an initial poor function of the transplanted kidney. The T lymphocyte inflammatory response is characteristic in acute cellular rejection; the degree of tubulitis, together with the amount of affected parenchyme, are important factors. The proportion of cellular sub-populations, such as plasma cells and macrophages, is also important, as they can be related to antibody-mediated humoral rejection. Immunofluorescent or immunohistochemical studies are necessary to rule out C4d deposits or immunogloblulins. The presence of abundant deposits of C4d in tubular basement membranes supports a diagnosis of humoral rejection, as does the presence of capillaritis, glomerulitis which, together with vasculitis, are typical diagnostic findings in C4d negative cases. Interstitial fibrosis, tubular atrophy and glomerular sclerosis, although non-specific, imply a chronic phase. Transplant glomerulopathy and multilamination in more than 6 layers of the tubular and glomerular basement membranes are quasi-specific characteristics of chronic humoral rejection. Electron microscopy is essential to identify of these pathologies as well as to demonstrate the presence of other glomerular renal diseases.

[Thrombotic microangiopathy/haemolytic uraemic syndrome. Histopathology update]. / Microangiopatía trombótica/síndrome hemolítico urémico. Actualización de sus características histopatológicas.

Thrombotic microangiopathy (TMA) encompasses different entities known as haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). The histopathological characteristics have remained constant since the initial description and consist in glomerular-type affectation with the presence of double contours, mesangiolysis and microthrombi. It is generally accepted that the vascular damage is related to the prognosis. Ultrastructure, together with conventional histology, shows notable changes in both capillaries and endothelial cells. A comprehensive histopathological study of the renal biopsy, using electronmicroscopy, is useful in the confirmation of a clinical suspicion and demonstrates the pathogenetic mechanisms in the microcirculatory damage. The close resemblance between the ultrastructural appearance and that seen with the light microscope of TMA and transplant glomerulopathy (TG) is precisely what suggests that both entities are subject to the same etiopathogenetic mechanism in which the endothelial cell is targeted. Recent advances in the pathology of atypical HUS, its relation with complement system and the discovery of specific therapeutic targets, has rekindled an interest in the study of TMA and the importance of renal biopsy.

Manejo de síndrome hemolítico urémico atípico en la paciente gestante / Management of atypical uremic hemolytic syndrome in pregnant patient

El síndrome hemolítico urémico atípico es una variante de la microangiopatía trombótica caracterizada por presentar anemia hemolítica no autoinmune, trombocitopenia y fallo renal agudo como consecuencia de una excesiva activación del Sistema del complemento. Hasta en un 60% de los pacientes presentan mutaciones en los genes que codifican el sistema del complemento. Se requiere un factor desencadenante para su manifestación, entre los que se encuentra la gestación. Es una entidad que presenta una elevada morbimortalidad, que puede disminuir de forma relevante si se realiza un diagnóstico precoz y se inicia tratamiento adecuado. La administración de eculizumab ha demostrado la interrupción rápida del proceso, con reducción de la necesidad de terapias de depuración extrarrenal y mejoría de la función renal y pronóstico de las pacientes.(AU)

Atypical uremic haemolytic syndrome is a variant of thrombotic micro-andiopathy characterized by non-autoimmune hemolytic anemia, thrombocytopenia and acute renal failure as a result of excessive activation of the complement. Up to 60% of patients have mutations in the genes that encode the complement system. A disensing factor is required for its manifestation, including gestation. It is an entity with a high morbidity, which can decrease drastically if an early diagnosis is made and appropriate treatment is initiated. Administration of ecuilizumab has demonstrated rapid process disruption, reducing the need for extrarenal purification therapies and improving renal function and patient prognosis.(AU)