A case of smoldering acute leukemia: long survival duration of 3 years and 9 months after the diagnosis.

A typical case of smoldering acute leukemia has been followed up for long-standing course. This 73 year-old woman survived 3 years and 9 months after diagnosis of acute myelogenous leukemia. The hematological study on admission showed hypoplastic bone marrow with 51.6% of abnormal myeloblasts, although a few myeloblasts were seen in the peripheral blood. Intensive anti-leukemia chemotherapy was withheld during the whole course except on the terminal acute phase. Three episodes of pneumonia occurred and then, the proliferation of leukemic cells subsided concomitnantly after the exacerbation of infection. The direct and/or host-mediated anti-tumor effect by infectious organism was suggestive in this case. The labeling index with 3H-TdR of leukemic cells was 4.9%, suggesting the slow multiplication. Positive tuberculin reactivity and normal ratio of lymphocyte blastogenesis confirmed the preserved cellular immunity. These factors might be considered to be closely related with the smoldering course of this particular case.