CLONAL CHROMOSOMAL-ABNORMALITIES AS DIRECT EVIDENCE FOR CLONALITY IN NASAL T-NATURAL-KILLER-CELL LYMPHOMAS

Nasal T/natural killer (NK) cell lymphoma is a distinct clinicopatholo gic entity which is more prevalent in Asia than in America and Europe. The clonal nature of the infiltrating lymphoid cells is difficult to demonstrate because of the lack of immunologic markers for clonality a nd the absence of clonal T-cell receptor gene rearrangement in most ca ses. In this study, clonal chromosomal abnormalities were detected in the tumour cells from four patients with nasal T/NK cell lymphoma. Thi s finding provided direct evidence for clonality of the disease. Moreo ver, nonrandom cytogenetic abnormalities, including isochromosome for the short arm (p) of chromosome 6, isochromosome for the long arm (q) of chromosome 1, partial deletion of 6q, and aberrations at 11q, were disclosed. Isochromosome 6p was the sole structural abnormality in one patient, which may be a pathognomonic change in nasal lymphoma.