Figure 1. Large B-cell lymphoma with IRF4 rearrangement from the tonsil.
A) H&E 20X of tonsil demonstrating squamous mucosa overlying an atypical lymphoid proliferation. B) H&E 400X demonstrating atypical cells with round to irregular nuclear contours, vesicular chromatin, and prominent nucleoli. C, A subset of atypical lymphocytes expressed weak BCL6 (400X), while (D) >95% of atypical lymphocytes strongly expressed MUM1 (400X). The cells lacked BCL2 and CD10. E) FISH demonstrated separated red and green probes from the IRF4 gene break-apart probe.