This 70 y/o male patient presented with long-standing history of chronic fatigue, anemia, and weight loss. Work-up revealed a large mass in descending colon and a left hemi-colectomy was performed. The specimen showed a 5.5 cm submucosal mass with focal mucosal ulceration. This section shows diffuse sheets of tumor cells beneath an intact large bowel mucosa. The final diagnosis was solitary plasmacytoma (see next image).