Solitary extramedullary plasmacytoma of the rectum complicating ulcerative colitis.

Solitary extramedullary plasmacytoma (EMP) arising in the rectum is an extremely rare clinical entity. Only ten cases have been reported in the English-language literature. We experienced a case of an EMP in the rectum of a 55-year-old man with an 8-year history of proctitis-type ulcerative colitis (UC). The plasmacytoma appeared as an 8-mm semipedunculated polypoid lesion in the actively inflamed rectal mucosa when the remittent UC flared. The tumor was treated using endoscopic mucosal resection. This is the second case of rectal EMP associated with UC after a similar report was published in 2004. Both patients had a chronic history of proctitis-type UC and were taking no immunosuppressive agents that could cause Epstein-Barr virus-associated plasmacytoma, such as thiopurines. The UC activity seemed to correspond well with the development of the rectal EMP. Therefore, we herein discuss a possible association between rectal EMP and UC and review the past literature of rectal EMP.