1. Pathology Department, Center of Medical Education and Clinical Investigation (CEMIC), Av. Galván 4102, Buenos Aires (1431), Argentina
2. Hospital Britá nico, Pedriel 75, Buenos Aires (1280), Argentina
3. Pathology Department, Hospital Nacional de Pediatría, Dr Prof. J.P. Garrahan, Combate de los Pozos 1881, Buenos Aires, Argentina