CLONAL AND NON-CLONAL KARYOTYPICALLY ABNORMAL-CELLS IN HEMOPHAGOCYTICLYMPHOHISTIOCYTOSIS

We studied chromosomes in bone marrow (BM) or peripheral blood cells o f nine patients with haemophagocytic lymphohistiocytosis (HLH); three of them had a family history of HLH and four others underwent concurre nt Epstein-Barr virus (EBV) infection. In addition to a large populati on of normal mitotic cells, karyotypically abnormal clonal cells were found in two patients, abnormal clonal cells and a nonclonal (single) abnormal cell in one, and nonclonal abnormal cells in three. All the s ix patients with chromosome abnormalities died of progressive disease; one of them also had EBV infection and EBV-associated clonal prolifer ation. Two of three patients with EBV infection and only normal mitoti c cells in BM completely recovered from the disease. Although HLH did not show histological and/or haematological evidence of a neoplastic d isease, clonal chromosome abnormalities and the fatal clinical outcome found in some of the patients suggest that the disease may be heterog enous and include malignancy. HLH patients with karyotypically abnorma l clonal cells in BM should warrant more intensive chemotherapy than t hat presently being applied to them and should be considered as candid ates for BM transplantation.