SECTION EDITOR: JULIA C. IEZZONI, MD
Diagnosis: Diffuse large B-cell lymphoma (DLBCL) of the thyroid
The results of flow cytometry were suggestive of a B-cell non-Hodgkin lymphoma. A biopsy specimen showed admixed small and large lymphoid cells with some residual thyroid follicles (Figure 2, lower left side).There was also an area with numerous large cells and abundant single-cell necrosis (Figure 3). Immunohistochemical staining was positive for CD20 (Figure 4). Additional immunohistochemical stains (not shown) revealed that subsets of the large cells expressed MUM1/IRF4 and CD43. The small lymphocytes included numerous CD20+ B cells as well as admixed CD3+ small T cells. CD21 revealed rare disrupted aggregates of follicular dendritic cells. The Ki67 proliferation index was 20% to 30% overall, with staining of most of the large cells. In situ hybridization was negative for Epstein-Barr virus–encoded RNA. In situ hybridization for immunoglobulin light chains showed polytypic plasma cells expressing a κ or λ light chain. The overall findings were diagnostic for DLBCL of the thyroid.
Pathology Quiz Case 1: Diagnosis. Arch Otolaryngol Head Neck Surg. 2011;137(8):832-833. doi:10.1001/archoto.2011.126-b