Refractory Primary Duodenal Plasmacytoma Displaying t(11;14): A Report of a Rare Case.

Extramedullary plasmacytoma (EMP) involving the digestive tract is a very rare entity that represents only a very small fraction of multiple myeloma (MM) cases. We describe an unusual case of a 71-year-old man with EMP involving the duodenum who initially presented to the emergency room with melena. The final diagnosis was duodenal plasmacytoma with t(11;14), and the diagnosis was reached by fibroscopy with biopsy and immunohistochemistry (IHC). The patient received local radiotherapy and showed failure three months after treatment. Then, he was administered daratumumab-based treatment associated with Revlimid and dexamethasone (DRD). To our knowledge, this is the first report showing duodenal involvement by EMP with t(11;14).