April 2018 — Hematopathology

A 40-year-old female presented with abdominal pain and diarrhea. Abdominal CT scan showed significant wall thickening of cecum.  Right hemicolectomy was performed.  Histologic sections revealed an extensive atypical lymphoid infiltrate involving the full thickness of the cecal wall. It is composed of a diffuse to vaguely nodular proliferation of intermediate to large atypical lymphoid cells with round to slightly irregular nuclear contours, coarse chromatin, and moderate to ample pale cytoplasm. Some of the cells have a slightly plasmacytoid appearance. The tumor cells are positive for CD20, BCL6 (90%), and IRF4/MUM1 (90%), are suspicious for being kappa light chain restricted, have an elevated proliferation index per Ki-67 staining (90%), and are negative for CD3, CD5, CD10, CD21, CD23, CD138,  BCL2, cyclinD1 and MYC. No underlying CD21 or CD23-positive follicular dendritic cell meshworks are appreciated.  Interphase FISH studies demonstrated rearrangement of BCL6 and IRF4 but not of BCL2 or MYC.

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Hee Eun Lee, M.D., Ph.D
Resident, Anatomic and Clinical Pathology
Mayo Clinic
Ellen McPhail, M.D.
Consultant, Hematopathology
Mayo Clinic
Associate Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine
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