PRECURSOR LANGERHANS CELL HISTIOCYTOSIS - AN UNUSUAL HISTIOCYTIC PROLIFERATION IN A PATIENT WITH PERSISTENT NON-HODGKIN LYMPHOMA AND TERMINAL ACUTE MONOCYTIC LEUKEMIA

Background. Langerhans cell precursors are considered to be identical to their mature counterparts except for the lack of Birbeck granules. Proliferations composed of such histiocytes appear to be uncommon. Methods. Standard immunophenotypic, molecular genetic, and DNA content studies were used to characterize various hematopoietic disorders, including a proliferation of precursor Langerhans cells, which arose sequentially in a patient. Results. The patient studied initially had a low-grade, B-cell, non-Hodgkin lymphoma and subsequently had an unusual histiocytic proliferation (precursor Langerhans cell histiocytosis) in cutaneous and lymph node sites. The patient eventually died of acute myelogenous leukemia (FAB, M5). Conclusions. A larger series is required to determine the significance of the precursor Langerhans cell phenotype, particularly with respect to the development of acute myelogenous leukemia.