Leucemia agresiva de células natural killer en un paciente pediátrico / Agressive NK-cell leukemia in a pediatric patient

Resumen Introducción: Las neoplasias de células natural killer (NK) son poco frecuentes y representan <5% de todas las neoplasias linfoides. Comprometen diferentes entidades clínicas, como la leucemia de células NK, que es una neoplasia hematológica altamente agresiva con un pronóstico precario, que se presenta en hombres jóvenes y se observa con mayor frecuencia en ascendencia asiática. El virus de Epstein-Barr (VEB) parece estar relacionado con la patogenia de esta leucemia. Caso clínico: Se presenta el caso de un paciente de sexo masculino de 1 año y 7 meses de edad, quien inició su padecimiento con síndrome anémico, febril, infiltrativo e hiperleucocitosis. En el aspirado de médula ósea se detectaron blastos de morfología L2 (96%), inmunofenotipo CD56 (80.87%) y desoxinucleotidil transferasa terminal (84.11%). En la biopsia de médula ósea se identificó CD2+ membranoso, CD3+ citoplásmico y CD56+ membranoso; la serología para VEB fue positiva. El paciente recibió dos esquemas diferentes de quimioterapia basados en metotrexato, ifosfamida, etopósido, dexametasona y L-asparaginasa, y se documentó remisión parcial. Actualmente, se encuentra vivo con la enfermedad. Conclusiones: La leucemia de células NK es rara en adultos jóvenes, pero aún más en pacientes en edad pediátrica. Además, es de muy difícil tratamiento, ya que solo se cuenta con algunos reportes de casos, la sobrevida es de semanas a meses y las oportunidades de tratamiento se limitan. Recientemente, se ha evidenciado la utilidad del trasplante de médula ósea alogénico o células de cordón umbilical, y se ha logrado una sobrevida a 2 años. Las posibilidades terapéuticas en estos pacientes se encuentran en estudio. Se espera lograr en un futuro cercano la remisión completa y sobrevida a 5 años.

Abstract Background: Natural killer (NK) cell neoplasms are rare and represent <5% of all lymphoid neoplasms. They involve different clinical entities, of which one is NK cell leukemia, a highly aggressive hematologic neoplasm with poor prognosis that presents in young men and is more frequently seen in Asian descent. Epstein-Barr virus (EBV) seems to be related to the pathogenesis. Case report: A male patient of 1 year and 7 months of age, who began his condition with anemic, febrile, infiltrative syndrome and hyperleukocytosis is described. Bone marrow aspirate showed L2 morphology blasts (96%), CD56 (80.87%) and terminal deoxynucleotidyl transferase (84.11%) immunophenotype. Bone marrow biopsy showed membranous CD2+, cytoplasmic CD3+ and membranous CD56+; serology positive to EBV. The patient received two different chemotherapy schemes based on methotrexate, ifosfamide, etoposide, dexamethasone and L-asparaginase, which resulted in partial remission. Currently, the patient lives with the disease. Conclusions: NK cells leukemia is rare in young adults, but even more in pediatric patients, for which it is very difficult to treat because only a few cases have been reported in the literature, the survival varies from weeks to months and the chances of treatment are limited. Recently, the usefulness of allogeneic bone marrow transplantation or umbilical cord cells has been demonstrated, achieving a 2-year survival. The therapeutic possibilities in these patients are under study. In the near future, we hope to achieve the complete remission of the disease and a 5-year survival.

Heterotopia pancreática yeyuna yuxtahepática y en quiste de conducto colédoco / Jejunal juxtahepatic and common bile duct (ductus choledochus) cystic pancreatic heterotopia

Se exponen 3 casos con hallazgo incidental de páncreas heterotópico, en autopsia y 2 piezas quirúrgicas para hacer una breve revisión del tema. Casos: 1. Mujer de 53 años de edad fallecida por neumonía de focos múltiples. Durante el estudio post mortem se encontró, a nivel del segmento yeyunal, un nódulo constituido histológicamente por múltiples conductos con epitelio columnar y fibras anchas desorganizadas de músculo liso. 2. Preescolar varón de 2 años 11 meses de edad con diagnóstico de quiste de colédoco y resección del mismo. En uno de los cortes de pared se observó una banda de tejido que a la microscopía de luz correspondía a tejido pancreático sin alteraciones. 3. Escolar mujer de 6 años 10 meses de edad con diagnóstico de síndrome de Byler candidata a transplante hepático. Los cortes histológicos del explante en la región del hilio revelaron grupos multifocales de conductos y acinos pancreáticos sin presencia de islotes. Conclusión: La heterotopia pancreática es un hallazgo infrecuente que se puede observar a cualquier nivel del tracto gastrointestinal e inclusive fuera del mismo, por lo que la caracterización histopatológica de esta alteración permite distinguirla de otras lesiones. Pese a su conducta habitualmente benigna y asintomática, ocasionalmente puede dar origen a cuadros obstructivos, hemorrágicos, inflamatorios o neoplásicos.

We report three cases of pancreatic heterotopia incidentally found (one in autopsy and two in surgical pieces) with a brief review of the literature. Cases: 1. A fifty-three-year-old woman who died of bronchopneumonia. During post-mortem examination, a nodule (hystologically formed by multiple ducts lined by columnar epithelium and broad disarranged smooth muscle fibers) was found at the level of jejune. 2. 5-year, 11-month-old male with diagnosis ofcholedochal cyst. In the resected specimen, one of the mural slices showed a tissue stripe that under light-microscope examination corresponded to normal pancreatic tissue. 3. 6-year, 10-month-old female diagnosed with Byler syndrome who was recipient of liver transplant. Slices taken from the hilum in the resected specimen revealed multiple clusters of pancreatic acini and ducts without evidence of endocrine islets. Conclusion: Pancreatic heterotopia is an uncommon finding, which may be found at any level of the gastrointestinal tract, and even outside it. Histopathologic studies allow to distinguish this disorder from other lesions. Despite its commonly benign and asymptomatic behaviour, it may sometimes produce obstruction, hemorrhage, inflammation or neoplasms.

Geographic and ontogenic variability in the venom of the neotropical rattlesnake Crotalus durissus: pathophysiological and therapeutic implications

A comparative study was performed on the venoms of adult specimens of the neotropical rattlesnake, Crotalus durissus, from Guatemala, Costa Rica, Venezuela and Brazil, together with the venom of newborn specimens of C. d. durissus from Costa Rica. Venoms from Brazil (C. d. terrificus) and from newborn specimens of C. d. durissus presented an electrophoretic pattern characterized by the predominance of bands with molecular mass of 36 and 15 kDa, whereas those of adult specimens of C. d. durissus from Guatemala and Costa Rica, and C. d. cumanensis from Venezuela, showed a conspicuous band of 62 kDa, and additional bands of 36, 29 and 15 kDa. Moreover, venoms from C. d. terrificus and C. d. cumanensis showed a prominent band of < 10 kDa that probably corresponds to crotamine, since a 'crotamine-like' activity was detected in these venoms upon intraperitoneal injection in mice. Venoms of C. d. terrificus, C. d cumanensis and newborn C. d. durissus induced higher lethal and myotoxic effects than those of adult C. d. durissus. In contrast, adult C. d. durissus and C. d. cumanensis venoms induced hemorrhage, whereas venoms of C. d. terrificus and newborn C. d. durissus lacked this effect. All venoms showed coagulant effect in plasma, the highest activity being observed in the venom of newborn C. d. durissus. An anti-crotalic antivenom produced by Instituto Butantan (Brazil), using C. d. terrificus venom as antigen, was effective in the neutralization of lethal, myotoxic and coagulant effects of all venoms studied, being ineffective in the neutralization of hemorrhagic activity of the venoms of C. d. cumanensis and C. d. durissus. On the other hand, a polyvalent antivenom produced by Instituto Clodomiro Picado (Costa Rica), using the venoms of C. d. durissus. Bothrops asper and Lachesis stenophrys as antigens, was able to neutralize lethal, myotoxic, coagulant and hemorrhagic effects of C. d. durissus venom, but was ineffective in the neutralization of lethality and myotoxicity of C. d. terrificus, C. d. cumanensis and newborn C. d. durissus venom. The high toxicity of South American and newborn C. d. durissus venoms is related to the presence of high concentrations of the neurotoxic phospholipase A2 complex 'crotoxin'. Accordingly, antivenom from Instituto Butantan has a much higher titer of anti-crotoxin antibodies than antivenom from Instituto Clodomiro Picado. Crotalus durissus represents an example of intraspecies variation in venom composition and pharm