Abstract
A malignant histiocytosis (MH) had been considered a main entity of the hemophagocytic syndrome (HPS), but as a result of advances in immunological and molecular biological diagnostic technology in the 1990s, many of the cases diagnosed as MH have been re-categorized as non-Hodgkin's lymphoma.In 1984, we reported 8 cases which had been clinically diagnosed as so-called malignant reticulosis and subsequently diagnosed as MH based on the findings of postmortem examination. When we re-evaluated these 8 cases by various approaches which included immunohistochemical examinations against B, T / NK, histiocytic markers, cytotoxic molecules and oncogene products as well as in situ hybridization (ISH) to detect EB virus encoded small RNAs ( EBER), it turned out that half of them were finally diagnosed as B-cell lymphoma and half as T-cell lymphoma ; in addition, two cases of T cell lymphoma were cytotoxic lymphoma.
It was reported that the extra-nodular NK/T cell lympoma was the major causes of LAHS, however, this study of 8 cases showed that lymphoma cells in all cases were negative for CD56, one of the NK cell marker. Analysis of the EBV infection by ISH indicated that the EBER-1 was detected only one case among 4 T cell-LAHS cases.
