A Durable Response of Primary Advanced Colonic Plasmacytoma Using a Combination of Surgical Resection and Adjuvant Bortezomib: A Case Report and Literature Review

BACKGROUND: Primary isolated extra-medullary plasmacytoma (EMP) is a rare entity that most commonly involves the nasopharynx or upper respiratory tract. Only 10% of cases involve the gastrointestinal tract, mainly the small intestine and the stomach. Involvement of the colon is extremely rare with less than 40 reported cases worldwide. CASE PRESENTATION: We report a case of a 57-year-old man who was presented with a 3-week history of fresh bleeding from the rectum. Colonoscopy showed a polypoidal mass arising from the ascending colon; biopsy showed clonal plasmacytosis and a primary colonic solitary EMP diagnosis was made after exclusion of multiple myeloma (MM). Accordingly, the patient underwent a right hemicolectomy, followed by 6 cycles of bortezomib, cyclophosphamide, and dexamethasone (VCD). The patient continued to be disease-free 30 months after the completion of his chemotherapy. CONCLUSION: To our knowledge, this is the first reported case of primary colonic plasmacytoma managed with surgical resection followed by an adjuvant bortezomib-based regimen with a durable response.