FNAB with cell block is an equally effective alternative to core biopsy and excisional biopsy for assessment of MYC, BCL2, and BCL6 FISH, which is required for identification of the clinically aggressive subset of large B-cell lymphomas that carry both MYC and BCL2 rearrangements. The gene discussed is BCL6; the disease is B-cell non-Hodgkin lymphoma.