A familial occurrence of natural killer cell--T-lymphocyte proliferation disease in two children.

Several reports describe the association of hyperlymphocytosis with neutropenia. This syndrome, named lymphoproliferative disease, is characterized by a chronic indolent clinical course, bone marrow lymphocyte infiltration, and granulopenia of central origin. The proliferating lymphocytes share large granular lymphocyte natural killer cell and T-lymphocyte characteristics. They are either of monoclonal or polyclonal origin. In this report the familial occurrence of a similar syndrome observed in two children is described. Lymphocyte morphologic abnormalities including nuclear pockets, were noted, a feature usually present in leukemic cells. Lymphocyte proliferation was distinct in each case as shown by the presence of a predominant CD4+ cell population in one and a predominant CD8+ population in the other. Monoclonal gene rearrangements of T-cell receptor beta-chain gene were found although clonal variations occurred with time in one patient. The cause of this unique familial occurrence of monoclonal lymphoproliferation associated with neutropenia is unknown.