Tyrosine kinase inhibitors (TKIs) are standard therapy for chronic myeloid leukemia (CML). However, the effects of these agents on mature B cell lymphoma are not well known. We describe a 50-year-old man who was diagnosed with CML in the chronic phase and treated with imatinib. After 3 years of imatinib therapy that achieved a complete cytogenetic response of CML, he developed Philadelphia-negative follicular lymphoma (FL). Rituximab monotherapy induced a partial response of FL, and he subsequently achieved a major molecular response (MMR) of CML. Three years later, however, the MMR was lost, followed by the progression of FL. Imatinib was switched to nilotinib for the treatment of CML, while we chose watchful waiting for FL. He achieved MMR again under treatment with nilotinib for 8 months including one month of substitutional use of dasatinib due to adverse events, but thereafter nilotinib was switched to bosutinib due to hyperbilirubinemia. With the administration of second-generation TKIs (2G-TKIs) for a total of 18 months, he achieved a complete response to FL without antilymphoma treatment. This is the first report to suggest that 2G-TKIs may have direct or indirect effects on FL.

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Pure erythroid leukemia (PEL) is characterized as a neoplastic erythroid hyperproliferation with maturation arrest, showing highly complex karyotypes, prominent clonal evolution, and a very aggressive clinical course. Here, we describe two cases of PEL that evolved from myelodysplastic syndrome (MDS), focusing on the immunophenotypic, cytogenetic, and molecular features of these cases. Case 1: A 77-yearold woman was diagnosed with PEL that evolved from MDS-refractory cytopenia with multilineage dysplasia. Her disease progressed rapidly despite 5 cycles of azacitidine treatment. The bone marrow (BM) aspirate revealed hypercellular marrow with 92.4% erythroid cells, which expressed CD7 and CD36. Case 2: A 43-year-old woman had MDS-refractory anemia for more than 15 years. When her disease progressed rapidly, the BM aspirate revealed hypercellular marrow with 95.4% erythroid cells, which expressed CD235a. There were several significant findings in our cases. First, flow cytometric analysis of BM cells showed different stages of erythroid maturation. Second, cytogenetics revealed extremely complex karyotypes. Finally, immunohistochemistry showed strong nuclear staining for p53 in BM erythroid cells. We suggest that increased p53 protein expression is correlated with complex karyotypes and worse outcomes, indicating PEL with a high degree of malignant behavior.