A 50-year-old woman with a history of aplastic anemia developed cervical lymphadenopathy and atypical lymphocytosis. Atypical cells of lymph nodes were positive for CD3 and CD30 but negative for anaplastic lymphoma kinase (ALK). Bone marrow examination showed trilineage myelodysplasia. She was diagnosed with ALK-negative anaplastic large cell lymphoma (ALCL) with leukemic transformation and myelodysplastic syndrome (MDS) which presumably developed from aplastic anemia. The lymphoma was resistant to intensive chemotherapies, ultimately leading to death. Leukemic presentation of ALK-negative ALCL as an initial manifestation is extremely rare, and the progression of the disease may be influenced by MDS through alteration of immune functions.