[Paraneoplastic pancytopenia in a patient with undiagnosed lung cancer].

Pancytopenia can be caused by lack of bone marrow function and can have different origins. A 66-year-old woman was admitted with severe sepsis, and the blood results revealed pancytopenia. A bone marrow biopsy was performed, and the primary diagnosis was hypocellular acute myeloid leukaemia with 20% blasts, but a diagnosis of myelodysplastic syndrome (MDS) was considered. After 30 days without any chemotherapeutic treatment her peripheral blood was normalised. In the meanwhile she was diagnosed with a small cell lung cancer. In this case the MDS-like condition was caused by a paraneoplastic phenomenon to the undiagnosed lung tumour.