Indeterminate cell histiocytosis in association with later occurrence of acute myeloblastic leukaemia.

Indeterminate cell histiocytosis (ICH) is a proliferation of indeterminate CD1a+, CD68+, S100+ and CD207- dermal dendritic cells. We describe a 39-year-old man who developed diffuse ICH and, 6 years later, acute myeloblastic leukaemia (AML). He was treated with cyclophosphamide, etoposide and vinblastine until 2003. In August 2004, he presented dyspnoea, hyperpyrexia and infiltration of the lung parenchyma, compatible with an AML invasion, and died after a course of induction chemotherapy. Cytomorphology and immunophenotype analyses suggested an ICH clonal evolution. The leukaemogenic role of etoposide is discussed. ICH has previously been reported in association with B-cell malignancy, but only one case has shown systemic progression.