A Study to Analyze the Occurrence of Transformation From Myelodysplastic Syndrome to Acute Myeloid Leukemia in Patients With Myelodysplastic Syndrome Who Received Revlimid® 5 mg Capsules and Who Are Continuing or no Longer Continuing Revlimid Treatment

To analyze the occurrence of transformation from myelodysplastic syndrome (MDS) to acute myeloid leukemia (hereinafter referred to as transformation from MDS to AML) in patients with myelodysplastic syndrome with a deletion 5q cytogenetic abnormality (hereinafter referred to as del(5q)MDS) who received Revlimid® 5 mg Capsules (hereinafter referred to as Revlimid) and who are continuing or no longer continuing Revlimid treatment. 1. Planned registration period This period started on the date of initial marketing of Revlimid and will end on the day when the appropriateness of enrollment is assessed for all del(5qMDS) patients in the all-case surveillance. 2. Planned surveillance period This period started on the date of initial marketing of Revlimid and will end 3 years after the last enrolled patient begins receiving Revlimid.