A "Double-Hit" Lymphoma With Plasmablastic Features and Aberrant Keratin Expression Likely Transforming From Follicular Lymphoma.

Large B-cell lymphomas may exhibit morphology typical of a diffuse large B-cell lymphoma (DLBCL) or a Burkitt lymphoma. Rarely, they may exhibit either a blastoid morphology or features that are intermediate between a DLBCL and Burkitt lymphoma (the so-called intermediate/blastoid morphology); the term high-grade B-cell lymphoma (HGBL) is used to describe the latter. The presence of MYC and BCL2 rearrangements can be seen either in HGBL or in lymphomas with DLBCL morphology (so-called double-hit lymphoma) and rarely in plasmablastic lymphomas. Herein, we report a rare occurrence of a double-hit lymphoma with plasmablastic features in a patient with a history of follicular lymphoma (FL) aberrantly expressing keratin in the transformed component posing a diagnostic conundrum. Immunohistochemistry and molecular work-up in conjunction with clinical history were essential in arriving at the correct diagnosis and thus illustrating a diagnostic pitfall.