Colonic mucosa-associated lymphoid tissue in a renal transplant recipient: a case report

Extra-gastric (particularly colonic) lymphoma of mucosa-associated lymphoid tissue in the immunosuppressed solid organ transplant recipient is rare. We report a case of low-volume mucosa-associated lymphoid tissue lymphoma with colonic and bone marrow involvement in a renal transplant recipient that has been managed conservatively.

A 62-year-old Caucasian man, 14 years after kidney transplantation, was diagnosed as having extra-nodal marginal zone lymphoma of mucosa-associated lymphoid tissue with bone marrow and colonic involvement, after a colonoscopy identified mucosa-associated lymphoid tissue lymphoma in a sessile sigmoid polyp following surveillance fecal occult blood testing that returned a positive result. A gastric biopsy showed no evidence of Helicobacter pylori, but Helicobacter pylori immunoglobulin G was positive. He received Helicobacter pylori eradication treatment and is being managed expectantly. Immunosuppression was unchanged with prednisolone, mycophenolate mofetil, and cyclosporine A. Renal allograft function has remained stable.

This case highlights the unexpected occurrence of colonic mucosa-associated lymphoid tissue lymphoma in a kidney transplant recipient. The case emphasizes the importance of histopathological diagnosis of colonic lesions in this patient cohort because the unusual diagnosis of low-volume mucosa-associated lymphoid tissue lymphoma can be managed expectantly as it does not appear to be clinically aggressive in the immunosuppressed solid organ transplant.