Introduction: Over one hundred years ago, Thomas Hodgkin (1) described a clinical and anatomical condition characterized by “morbid appearances of the absorbent glands and spleen.” In the years that followed it became evident that Hodgkin had grouped together a number of different diseases on the basis of mere gross morphologic similarities. Numerous investigations since his report have served, from time to time, to delimit distinct entities having in common the characteristic of progressive lymphadenopathy, with or without hepatosplenomegaly. Leukemia was first described in 1845 by Virchow (2) and pseudoleukemia (aleukemic leukemia) in 1865 by Cohnheim (3). Lymphosarcoma, recognized since 1863 (Virchow, 4), was first clearly defined by Dreschfeld (5) in 1891, and by Kundrat (6) in 1893. Following this, lymphogranulomatosis (Sternberg, 1898) and leukosarcomatosis (Sternberg, 1904, 1908) were established as anatomical entities (7–9). More recently Brill, Baehr, and Rosenthal (1925), and Baehr, Klemperer and Rosenthal (1931) described follicular lymphoblastoma (10, 11). Finally, during the past decade, the terms reticulosis, reticulosarcomatosis and similar designations have appeared in the literature, referring also to cases of lymphadenopathy with or without hepatosplenomegaly, but characterized histologically by the presence of cells in reticular arrangement.