Follicular Lymphoma


Follicular lymphoma (FL) is a neoplasm composed of germinal centre B-cells and it forms in at least a partially follicular pattern. It accounts for about 20% of all lymphomas and occurs almost exclusively in adults (>18 years).  It primarily affects the lymph nodes, but can also involve the spleen, bone marrow, peripheral blood, and Waldeyer ring. FISH is used to identify rearrangements of BCL2, primarily the t(14;18)(q32;q21) translocation involving IGH which is identified in 80% of cases and BCL6 rearrangements which are identified in up to 15% of FL cases. 


  • Completed CGL Lymphoid Testing requisition form
  • FFPE Tumour specimen (see Specimen Guidelines, Cytogenetics FISH FFPE test type)
    • An H&E stained slide with the tumour region circled, and the estimated % tumour content written in the Tumour Content field of the requisition.  NOTE: A minimum of 10% tumour and at least 200 nuclei is required.
    • Specimen block and/or at least one unstained slide for each probe requested.
    • See our FFPE Guidelines for additional details.

NOTE: FISH analysis on a bone marrow aspirate for the purposes of staging is not performed, unless a lymph node is not available


  • Specimens are reported as Positive for a rearrangement, Negative for a rearrangement, or Negative for a rearrangement – extra signals
  • A negative result for BCL2 or BCL6 neither precludes the existence of such a rearrangement nor does it exclude a diagnosis of FL
  • BCL2 and BCL6 rearrangements are common in FL but may be identified in other mature B-cell neoplasms


Results are reported within fourteen days from receipt of specimen and completed requisition form.


FISH analysis is performed on the provided FFPE tissue using the following the dual-colour, break apart probes (Vysis): BCL2 (18q21) and BCL6 (3q27).