CD56-Positive Acute Myeloid Leukemia Following Treatment of Hairy Cell Leukemia with Cladribine – Report of 2 Cases and Review of the Literature

Treatment of hairy cell leukemia (HCL) with alfa-interferon and purine analogs significantly prolongs survival in these patients. However, with life prolongation, an increased risk of secondary malignancies has been reported. Acute myeloid leukemia (AML), as a second malignancy after HCL treatment is extremely rare and has been reported in only 12 cases so far. We here report additional 2 cases of CD56+ AML developed after sustained clinical remission of HCL achieved with cladribine (2 and 6 years after, respectively). The first patient refused chemotherapy and shortly thereafter died. The second patient responded to chemotherapy and was successfully allo-transplanted. Three years later, the patient is in stable clinical remission, which is a unique case in the literature. In conclusion, it is not clear whether development of AML in HCL patients is caused by mutagenic potential of the applied chemotherapy or by immune suppression/ perturbations as a characteristic of the underlying disease.