A DISEASE of unknown cause consisting of recurrent suppurative lymphadenitis, hepatosplenomegaly, rash, pulmonary infiltration, anemia, leukocytosis, and hypergammaglobulinemia was first described in four male children by Berendes et al and Bridges et al in 1957.1,2 Onset in infancy, death before the sixth birthday, and microscopic demonstration of a reticuloendothelial and pulmonary granulomatosis further delineated this disease as a new and distinct clinical entity. Shortly thereafter Landing and Shirkey described two boys with a similar clinical course and infiltration of their reticuloendothelial systems by histiocytes with foamy, lipoid cytoplasm containing a yellow-brown pigment.3 The two reports were thought to describe different diseases until 1965 when Carson et al reported 13 boys whose clinical findings overlapped both groups and whose biopsy or autopsy material contained both pigmented lipid histiocytes and granulomas.4 The pathogenesis remained a complete enigma, however, until Holmes et al and Quie et al in 1966 demonstrated