Rappaport in 1966 [10] introduced the term “malignant histiocytosis” to describe a disorder of “systemic, progressive, invasive proliferation of atypical histiocytes.” An identical disorder was observed by Scott and Robb-Smith in 1939 [11] and termed “histiocytic medullary reticulosis.” The most conspicuous clinical features of this disorder are enlargement of lymph nodes, liver, and spleen, and widespread multifocal involvement of the lymphatic and reticulohistiocytic system during the early phase of the disease. In the last 3 years clinical findings and therapeutic results were published [1, 6, 7, 14] and will be presented and discussed in the following.