Immunoproliferative Small Intestinal Disease Associated with Overwhelming Polymicrobial Gastrointestinal Infection with Transformation to Diffuse Large B-cell Lymphoma.

Immunoproliferative small intestinal disease (IPSID) is an extra-nodal B-cell lymphoma most commonly described in the Mediterranean, Africa, and Asia. It is associated with poverty and poor sanitation, and is rarely encountered in developed countries. A 26-year-old previously healthy, Marshallese male was transferred to our facility with a 6-month history of watery diarrhea, weakness, and cachexia refractory to multiple short courses of oral antibiotics. Stool cultures grew Campylobacter jejuni and Vibrio fluvialis. Endoscopic evaluation showed histologic evidence of Helicobacter pylori gastritis and gross evidence of whipworm infection found in the colon. Mesenteric lymph node biopsy cultures grew Escherichia coli. Histopathology and immunohistochemical stains of the small intestine were consistent with IPSID. He subsequently transformed to diffuse large B-cell lymphoma (DLBCL) with tonsillar involvement despite treatment with rituximab and an extended course of antibiotics. Systemic chemotherapy with six cycles of rituximab, cyclophosphamide, vincristine, doxorubicin, prednisone, and lenalidomide, resulted in remission of his diffuse B cell lymphoma. This case is illustrative of IPSID developing in a previously healthy individual due to overwhelming polymicrobial gastrointestinal infection by C. jejuni and other enteric pathogens with subsequent transformation to an aggressive DLBCL. IPSID should be considered in residents of developing countries presenting with refractory chronic diarrhea, weight loss, and mesenteric lymphadenopathy.