Ki-1 anaplastic large-cell lymphoma occurring at the site of ileocolonic anastomosis in a patient treated surgically for colonic adenocarcinoma: case report and review of the literature.

Systemic anaplastic large-cell lymphoma is an uncommon type of non-Hodgkin lymphoma characterized by strong expression of the Ki-1 (CD30) antigen. Gastrointestinal involvement typically is less common than in other types of non-Hodgkin's lymphoma. We report a case of CD30-positive anaplastic large-cell lymphoma occurring at the site of colonic anastomosis in an elderly patient who had been treated for colonic adenocarcinoma by right hemicolectomy 10 years previously. The lymphoma was a 2-cm mass composed of large, atypical cells infiltrating the mucosa, submucosa, and muscularis propria. Immunoperoxidase stain was strongly positive for Ki-1, and negative for LeuM1, L26, UCHL1, EMA, and cytokeratin. There have been numerous reports of unusual extranodal presentations of systemic anaplastic large-cell lymphoma; the only previously reported case involving the colon, however, occurred in the context of ulcerative colitis. Anastomotic recurrence is a relatively common complication of surgical therapy for adenocarcinoma, but the recurrent tumors are invariably adenocarcinomas. We are aware of no cases of lymphoma of any type occurring at the site of anastomosis after resection for adenocarcinoma.