Inmunodeficiencia Combinada Severa, reporte de pacientes chilenos diagnosticados durante el período 1999-2020 / Severe combined immunodeficiency, report of Chilean patients diagnosed during the 1999-2020 period

INTRODUCCIÓN: La inmunodeficiencia combinada severa (IDCS) corresponde a una de las formas más graves de inmunodeficiencia primaria, existiendo escasos datos nacionales sobre ésta. OBJETIVO: describir la epidemiología, complicaciones, pronóstico y uso de la vacuna BCG en pacientes chilenos con IDCS. PACIENTES Y MÉTODO: Estudio retrospectivo de pacientes diagnosticados con IDCS entre los años 1999 y 2020 por médicos inmunólogos a lo largo de Chile. El diagnóstico de IDCS se realizó conforme a los criterios propuestos por Shearer: linfocitos T (CD3+) < 300 células/μL y prolife ración 10% del límite de normalidad en respuesta a fitohemaglutinina o presencia de linfocitos T de origen materno. Se obtuvieron de la ficha clínica los datos correspondientes a: sexo, edad al diagnóstico, consanguinidad, región de origen, subpoblaciones linfocitarias, diagnóstico genético, complicaciones infecciosas y no infecciosas, vacunación BCG y sus complicaciones, edad de deriva ción al centro de TPH y causa de mortalidad no relacionada al TPH. RESULTADOS: se diagnosticaron 25 casos de IDCS en 22 familias entre los años 1999-2020. 78% varones, la edad media a la primera manifestación fue 2.3 meses (0-7), mientras que la edad media al diagnóstico fue de 3.4 meses (0 7). Un 16% de los casos tenía un antecedente familiar de IDCS. Un 40% de los casos fueron diag nosticados en la Región Metropolitana. El inmunofenotipo más frecuente fue T-B-NK+ (48%). Se realizaron estudios genéticos en 69,5% de los casos, siendo los defectos genéticos en RAG2 (39%) la causa más frecuente. Un 88% de los casos recibió la vacuna Bacillus Calmette-Guerin (BCG) previo al diagnóstico, incluidos 2 pacientes con historia familiar positiva, 36% de los vacunados experimentó complicaciones de la BCG. La edad media a la derivación a trasplante fue de 7,4 meses (5-16). De los 25 pacientes, 11 fallecieron previo a la derivación a un centro de trasplante. CONCLUSIÓN: En Chile existe un retraso clínicamente significativo entre las primeras manifestaciones y el diagnóstico de IDCS, así como un importante retraso en la derivación a centros de trasplante. La mayoría de los pacientes con IDCS reciben la vacuna BCG, pese a tener antecedentes familiares, y experimentan frecuentemente complicaciones de la vacuna.

INTRODUCTION: Severe combined immunodeficiency (SCID) is the most severe form of primary immunodeficiency. To date, there is little local information about this disease. OBJECTIVE: To describe the epidemiology, complications, prognosis, and use of the BCG vaccine in Chilean patients with SCID. PATIENTS AND METHOD: Retrospective review of the clinical records of patients diagnosed with SCID by clinical immunologists between 1999 and 2020 throughout Chile. SCID was diagnosed according to the cri teria proposed by Shearer: T lymphocytes (CD3+) < 300 cells/μL and proliferation 10% of the limit of normality in response to phytohemagglutinin or presence of T lymphocytes of maternal origin. Data collected from the clinical records were: sex, age at diagnosis, consanguinity, region of origin, lymphocyte subpopulations, genetic diagnosis, infectious and non-infectious complications, BCG vaccination and its complications, age at referral to the bone marrow transplant (BMT) center, and cause of non-BMT-related mortality. RESULTS: Between 1999 and 2020, 25 patients were diagnosed with SCID. 78% of them were male, mean age at first manifestation of the disease was 2.3 months (0-7), while the mean age at diagnosis was 3.4 months (0-7). 16% of patients had a family history of SCID. 40% of cases were diagnosed within the Metropolitan Region. The most frequent immuno- phenotype was T-B-NK+ SCID (48%). Genetic studies were done in 69.5% of cases, mutations in the RAG2 gene were the most common etiology of SCID (39%). 88% of SCID patients received the Bacillus Calmette-Guerin (BCG) vaccine before diagnosis, including 2 cases with a known family history of SCID. 36% of those who received the vaccine had BCG-related complications. The mean age at referral to a bone marrow transplant center was 7.4 months (5-16). 11/25 patients died before being transferred to a transplant center. DISCUSSION: There is a clinically significant delay between the first manifestations and the diagnosis of SCID in Chilean patients, as well as an important time gap between the diagnosis of SCID and referral to a center for BMT. Most SCID cases in Chile receive the BCG vaccine, despite a known family history of the disease, and frequently develop vaccine-related complications.

Guía clínica chilena de urticaria crónica espontánea / Chilean guidelines for chronic urticaria

Chronic urticaria (CU) is characterized by itchy wheals, angioedema or both lasting six weeks or more. It is classified as spontaneous (CSU) and inducible urticaria (CIndU), depending whether there is an identifiable trigger or not. CSU is the predominant form, affecting more than 75% of patients, although overlaps often occur. The prevalence of CSU throughout life is around 1.8% and predominates in women at a ratio of 2:1. The higher incidence of CSU is between 20 and 40 years of age and lasts between one to five years. However, in up to 20% of patients the disease may last longer. CSU not only hampers quality of life, but also affect performance at work and school. The diagnosis of CSU is mainly clinical, and laboratory tests are required depending on the clinical history of the patient. Extensive laboratory tests are usually unnecessary. Second generation anti-histamines are used as first line treatment for CSU treatment. In refractory patients, systemic treatments, such as cyclosporine or omalizumab are suggested. We herein report the first Chilean CSU guidelines.

Inmunodeficiencias primarias en niños gravemente enfermos: a propósito de 3 casos clínicos / Primary immunodeficiencies in seriously ill children: Report of 3 clinical cases

Las inmunodeficiencias primarias (IDP) son enfermedades congénitas causadas por alteraciones cuantitativas o funcionales de la respuesta inmunitaria. Se caracterizan por predisposición a infecciones, autoinmunidad, alergia y enfermedades linfoproliferativas. Objetivo: Reportar 3 casos de lactantes menores con IDP que se manifestaron como infecciones graves de curso inhabitual. Casos clínicos: Se presentan 3 pacientes diagnosticados como IDP en su estadía en la Unidad de Paciente Crítico Pediátrico. El primero corresponde a un lactante de 4 meses con neumonía multifocal extensa a quien se diagnosticó un síndrome de inmunodeficiencia combinada severa ligada a X; el segundo es un lactante de 8 meses que se manifestó como una adenitis mesentérica por Candida lusitaniae y que correspondió a enfermedad granulomatosa crónica, y el tercero se trata de un lactante de 6 meses que se presentó con un ectima por Pseudomona y se diagnosticó una agammaglobulinemia ligada a X. Conclusión: El diagnóstico de IDP debe sospecharse en presencia de una infección de evolución arrastrada que no responde a tratamiento habitual. Se discuten los casos y se presenta una puesta al día de las patologías diagnosticadas.

Primary immunodeficiency diseases (PID) are congenital disorders secondary to an impaired immune response. Infections, autoimmune disorders, atopy, and lymphoproliferative syndromes are commonly associated with this disorder. Objective: To present and discuss 3 infants diagnosed with PID. Clinical cases: The cases are presented of three patients with PID diagnosed during their first admission to a Paediatric Intensive Critical Care Unit. The first patient, a 4-month-old infant affected by a severe pneumonia, and was diagnosed as a Severe Combined Immunodeficiency Disease. The second patient was an 8-month-old infant with Candida lusitaniae mesenteric adenitis, and diagnosed with a Chronic Granulomatous Disease. The last patient, a 6-month-old infant presented with ecthyma gangrenosum and X-linked agammaglobulinaemia. Conclusion: PID should be suspected when an infectious disease does not responde to the appropriate therapy within the expected period. An update of each disease is presented.

Artritis idiopática juvenil de inicio sistémico y síndrome de activación macrofágica / Juvenile idiopathic arthritis of sistemic beginning and syndrome of macrophage activation

The macrophage activation syndrome (MAS) i a rare pediatric condition characterized by enhanced activation of the macrophage and T-cell system, with increased liberation of T-cell cytokines. Clinically it resembles a multiorgan failure syndrome of infectious etiology. There is still some debate as to the nomenclature of this syndrome, hemato-oncologists usually classify this syndrome as a histiocytic disorder, while rheumatologists define it as MAS. We review a patient in which MAS was diagnosed during the early stages of the disease. The patient had juvenile idiopathic arthritis (systemic presentation).