Gastrointestinal manifestations of extramedullary plasmacytoma: a narrative review and illustrative case reports.

Introduction Solitary extramedullary plasmacytoma are rare, solid-mass tumours which appear immunophenotypically similar to multiple myeloma. The diagnosis and management of gastrointestinal plasmacytoma is complex and requires multidisciplinary input. This study presents a narrative review of intra-abdominal extramedullary plasmacytoma, illustrated with two case studies. Methods The PubMed database was searched without date restrictions for reports of intra-abdominal extramedullary plasmacytoma to synthesise a narrative review. Electronic records were reviewed at a high-volume, quaternary soft-tissue sarcoma centre to identify patients with histopathologically confirmed extramedullary plasmacytoma affecting the gastrointestinal tract. Results Gastrointestinal extramedullary plasmacytomas can present with mass effect or organ-specific dysfunction. Techniques for tissue diagnosis of extramedullary plasmacytoma vary dependent on location, with a formal diagnosis often being made from a resected specimen. Management can include surgery, radiotherapy, systemic chemotherapy or a combination. No high-quality evidence base exists to guide treatment. Two case studies of operated gastrointestinal extramedullary plasmacytoma are presented at different phases of disease progression, with a resultant impact on survival. Conclusion Intra-abdominal extramedullary plasmacytoma is a rare and heterogeneous condition that lacks consensus guidelines for diagnosis and management. Collaboration between international specialist centres will create better quality evidence for treatment of this cohort.