Prognostic and predictive significance of the bcl-2/IgH translocation in malignant follicular lymphomas.

BACKGROUND: The t(14;18) translocation, which leads to an overproduction of the bcl-2 protein, supposedly occurs in almost all follicular lymphomas (FL) and can be detected by FISH methods or by PCR. Its detection is useful in monitoring the response to therapy and in assessing minimal residual disease in bone marrow. Recently it was observed that the translocation could become negative after treatment. The prognostic and predictive significance of this fluctuation is not entirely understood.

AIM: We intended to find significant correlations among morphological features, histological grades, immunohistochemical findings, and cytogenetical aberrations in malignant follicular lymphomas, in order to identify the prognostic and predictive value of the bcl-2/IgH translocation in these malignancies.

MATERIAL AND METHODS: We conducted a study on 79 patients with follicular lymphomas. The study was carried out on tissue samples selected from the "Victor Babes" National Institute of Pathology files. These samples were tested by immunohistochemistry and FISH.

RESULTS: Most of the cases (65.2%) were low-grade FL (grade 1-2). Approximately 58.8% of cases in the FISH study group presented t(14;18). In 66.6% of the cases with t(14;18), the immunohistochemical reaction for bcl-2 protein was positive. A significant positive correlation was found between the IHC positivity for bcl-2 and t(14;18) detected by FISH (p=0.04).

CONCLUSIONS: Bcl-2 t(14;18) plays an important role in the pathogenesis of follicular lymphoma. FISH is an important tool in the diagnosis, treatment and follow up of these malignancies, since the immunohistochemical testing is negative in a significant proportion of cases.