Abstract
Twenty one patients were diagnosed as “malignant histiocytosis (MH)” according to clinical mainifestations, for example severe inflamatory reactions, progressive pancytopenia, huge hepatosplanomegaly, and the presence of hemohagocytic cells in bone marrow. In comparison with large anaplastic cell lymphoma, the clinical features of “MH” patients were characterized by the systemic symptoms and rapid clinical course. Cells with histiocytic appearance in these patients were classified in to 3 subgroups on the basis of the morphologic atypism; blastic, intermediate, or mature type. Histiocytic cells from 17 out of 21 patients belonged to the blastic or intermediate type, suggesting the neoplastic nature. Hemophagocytic cells without remarkable atypism, which were observed in bone marrow of the most patients, showed the mature type appearance, and were recognized as activated histiocytes. In 6 “MH” patients with neoplastic cells, 3 patients were recognized as histiocytic disorder, 2 as T-cell one, and one as B-cell one according to the immunophenotype and immunogenotype.
Interestingly, one of the T-cell type showed phenotype of CD2+CD3-CD4-CD8-EAG+with large granular lymphocyte (LGL) appearance, and another CD2+CD3+CD4-CD8-EAG+LGL also increased in the terminal phase of a “MH” patient with B-cell neoplasm. In addition, either neoplastic or benign LGL disorders revealed “MH” like systemic symptoms in occasion. Thus, LGL/Tγ cells as well as the hemophagocytic cells are thought to play a main role for the hematopathologic and clinical manifestation of “MH” in reticuloendotherial system, especially in spleen, and hyper-production of cytokines by thesee cells may closely related the systemic and unreguratable symptoms, tentatively named “cytokine-crisis”
