Bone marrow findings in malignant histiocytosis and/or malignant lymphoma with concurrent hemophagocytic syndrome.

We examined bone marrow specimens from 19 patients with malignant histiocytosis (MH) and/or malignant lymphoma (ML) with concurrent hemophagocytic syndrome (HS) who suffered from high fever, hepatosplenomegaly, liver dysfunction, profound cytopenia, and erythrophagocytosis. There was little lymph-node enlargement or no tumor formation. The neoplastic cells in 3 patients exhibited histiocytes/macrophages phenotype with positive reactions for fluoride-sensitive nonspecific esterase, lysozyme and CD68 (KP1). Twelve other patients showed a T-cell (CD3) phenotype, in which 5 patients expressed CD30 (BerH2) as well. B-cell characteristics with CD20 (L26), CIg. nu lambda and gamma kappa were manifest in 2 patients, but indeterminate markers were found in the 2 remaining patients. Eighteen patients showed an infiltration of large neoplastic cells mainly with noncohesive interstitial growth pattern, ranging from 1.7% to 74.2% of the nucleated cells in the bone marrow. A large number of histiocytes/macrophages and dendritic cells was diffusely observed in 15 patients. Severely decreased hematopoiesis in all three series of hematopoietic cells was found in 16 patients. Bone marrow infiltration by the neoplastic cells and numerous reactive cells with erythrophagocytosis appears to be an important factor of profound cytopenia in patients of MH and/or ML with HS. The infiltrating pattern of the neoplastic and reactive cells in the bone marrow of MH and/or ML with HS was different from that of other types of peripheral T-cell ML, B-cell ML in high grade malignancy, and Hodgkin's disease. Cell characteristics and lineage of the neoplastic cells in MH and/or ML with HS are also discussed in this study.