Prevalence of "follicular lymphoma in situ" in consecutively analysed reactive lymph nodes

Patrick Adam (1) , Tobias Henopp (1) , Leticia Quintanilla-Martinez (1) , Falko Fend (1)

1 Institute of Pathology

Background: Follicular lymphoma "in situ" is defined as strongly BCL-2 positive B-cells in germinal centers of morphologically inconspicuous lymph nodes. Prevalence and biological and clinical significance of this lesion are still not clear. Methodology: All 1.294 reactive lymph nodes from unselected consecutive surgical specimens of 132 patients in a 3 months period were stained for BCL-2 protein. The t(14;18) translocation was investigated by FISH analysis. Results: Follicular lymphoma "in situ" was identified in 22 lymph nodes in 3/132 patients (2.3%) without evidence or history of malignant lymphoma and confirmed by detection of the t(14;18) by FISH. Interestingly, in one patient, a lymph node excised two years before also contained follicular lymphoma "in situ". Conclusion: We found a prevalence of 2.3% for "FL in situ" lesions in an unselected series of lymph nodes, as a surrogate for the normal population. Taking into account the incidence of manifest follicular lymphoma the progression risk of this lesion is probably limited. It can be speculated that a part of the follicular lymphoma "in situ" lesions indeed represent an early step in the lymphomagenesis, whereas others persist without further progression to overt follicular lymphoma. The underlying mechanisms, however, remain to be elucidated.

Mots clés: Medicine

Patrick Adam, Tobias Henopp, Leticia Quintanilla-Martinez, Falko Fend. Prevalence of "follicular lymphoma in situ" in consecutively analysed reactive lymph nodes. Histopathology, 2011, 59 (1), pp.139. ⟨10.1111/j.1365-2559.2011.03897.x⟩. ⟨hal-00661258⟩