Intra-abdominal extramedullary plasmacytoma: A case report and literature review

The incidence of extramedullary plasmacytoma (EMP) accounts for 3% to 4% of all cases of generalized plasmacytoma. Extramedullary plasmacytomas are predominantly located in the upper respiratory tract and nasopharynx, with only around 4% originating primarily in the gastrointestinal tract. The median age at diagnosis is approximately 55 years about 10 years earlier than in multiple myeloma and there is a higher incidence among males. These tumors exhibit a diverse phenotype that can result in varying degrees of mass effect and organ dysfunction based on their anatomical site. Although they display immunophenotypic characteristics similar to multiple myeloma, obtaining an in vivo tissue diagnosis can be particularly challenging for lesions situated within the abdominal cavity. Consequently, accurate diagnosis and effective treatment planning require a collaborative, multidisciplinary approach involving surgeons, hematologists, oncologists, radiologists, and pathologists.

We report the case of a 50 year old woman who presented an abdominal distension without any associated signs. An abdominal CT scan was performed who objectified a mass in the left hypochondrium and flank of 12 centimeters followed by a biopsy and a full blood test, which confirmed the diagnosis of extramedullary plasmocytoma kappa monotype. Surgery was not feasible, radiotherapy was thus carried out. After a follow up of 18 months, a TEP scan was performed showing the absence of any lesion suspected of progressive disease or residual metabolically active disease.