Anaplastic Ki-1-positive large cell lymphoma of the pancreas: a case report and review of the literature.

A case of Ki-1-positive anaplastic large cell lymphoma of the pancreas is presented. The patient complained of abdominal pain and was jaundiced. Examination of a biopsy specimen obtained by duodenal endoscopy revealed malignant lymphoma, and surgery confirmed a large mass located in the region from the intra-pancreatic tissue around the lower common bile duct to the peri-pancreatic lymph nodes. Histologically, this tumor was composed mainly of large and giant neoplastic cells. Immunohistochemically, these cells were diffusely positive for Ki-1 and CD45RO antigens, indicating the features of Ki-1 anaplastic large cell lymphoma with a T-cell phenotype among non-Hodgkin's lymphoma. The histologic types of the majority of malignant lymphomas of the pancreas reported previously were considered to be diffuse-type non-Hodgkin lymphoma (probably with predominance of the B-cell phenotype), except for a single Japanese lymphoma case with a T-cell phenotype. This is therefore the first known case of Ki-1 anaplastic large cell lymphoma of the pancreas.