Ulcerative colon T-cell lymphoma: an unusual entity mimicking Crohn's disease and may be associated with fulminant hemophagocytosis.

Primary gastrointestinal T-cell lymphoma is uncommon. Most arise from the small intestine and are usually associated with chronic celiac disease; the so-called enteropathy associated T-cell lymphoma. Primary colon T-cell lymphoma is much more rare. We present two patients with primary colon T-cell lymphoma. Both patients had chronic diarrhea and significant weight loss. Endoscopically, the lymphoma was characterized by the presence of multiple skipped ulcers distributed from the terminal ileum to the descending colon. It was differentiated from Crohn's disease by the absence of fistula or thickening of the intestinal walls. Histologically, the lymphoma was composed of medium to large atypical cells located in the ulcer base with extension to the muscular layer and the adjacent atrophic mucosa. Occasional increased intraepithelial lymphocytes were also seen. Immunohistochemically, the lymphoma cells and intraepithelial lymphocytes were CD3+, CD4-, CD56- and CD8-. It was difficult to diagnosis this unusual lymphoma by biopsy. Because most biopsy specimens showed mixed inflammation within which the lymphoma cell was sometimes hard to identify. Both patients died of fulminant hemophagocytic syndrome and Epstein-Barr virus genome was detected in the lymphoma cells using in situ hybridization on the final surgical specimens. Our study indicates that it is important to recognize this ulcerative colon T-cell lymphoma and to differentiate it from inflammatory bowel disease because of its much more aggressive clinical behavior.