Chromosomal abnormalities in a patient with smoldering adult T-cell leukemia: evidence for a multistep pathogenesis.

A cytogenetic study was performed on peripheral blood cells from a patient with smoldering adult T-cell leukemia (ATL). Four types of primary abnormal clones were found upon examination of a large number of karyotypically analysed cells cultured with and without phytohemagglutinin (PHA). However, human T-cell leukemia virus (HTLV) proviral DNA was confirmed to be monoclonal. This discrepancy can be explained by the hypothesis that these four primary abnormal clones were all derived from a leukemic clone with a normal karyotype and the same integration site of HTLV proviral DNA.