[Cytogenetic alterations found by chromosome analysis and fish technique in two patients with variant chronic...

Chromosomal studies in CLL have yielded poorer results than in other blood diseases because of the low mitotic index of the B cells. The FISH technique is a very useful tool for trisomy 12 detection in interphase nuclei in CLL, although this method cannot be a substitutive for conventional cytogenetics. The FISH technique was applied in two cases of CLL by means of satellite DNA probing specific for chromosome 12 according to the Oncor S 1370-CF kit protocol. Trisomy 12 was detected, along with other chromosomal abnormalities secondary to this trisomy. Both patients had lymphocyte counts lower than 5.0 x 10(9)/L and their peripheral blood immunophenotype showed 58% lymphocytes with lambda sIg of medium density, co-expressing CD5 and unable to form rosettes with mouse red-cells. Patient no. 1 was 46,XY/47,XY + 12/47,XY + 12,5q-, and patient no. 2 was 46,XX/47,XX + 12,14q-. The presence of secondary anomalies could explain the special clinico-haematological picture, characterised by low lymphocytosis and presence of irregular nuclei in mature lymphocytes, along with the lack of CD23 expression and rosette formation with mouse red-cells. FISH technique combined with chromosome analysis may prove a useful means for diagnosing and recognising variants or specific entities within low-grade lymphoproliferative syndromes.