Primary pancreatic lymphoma: clinicopathological analysis of 19 cases from Japan and review of the literature.

Primary pancreatic lymphoma (PL) is an extremely rare disease, and large-scale studies are rarely performed even in Western countries, in which all cases of PL reported to date were of the B-cell type. Little information regarding PL is available in Japan. Nineteen cases of PL were collected through a nationwide study in Japan, and paraffin-embedded specimens were processed for staining with hematoxylin and eosin and by immunohistochemical procedures. Clinicopathological findings were reviewed and compared with those reported in Western countries. The patient population consisted of 13 men and 6 women, ranging in age from 46 to 84 (average 62) years. Abdominal pain was the most common presenting symptom. Tumors were located in the pancreatic head (12 cases), tail (4 cases) and body (2 cases), and ranged in size from 4 to 17 cm. Clinical stage was I(E) in 9 cases and II(E) in 10. Radical resection was performed in 10 cases and bypass operation in 1, followed by chemotherapy in 8. Immunophenotypically, 15 cases were B-cell and 4 were T-cell lymphomas. Seventy-three percent of B-cell tumors were diffuse large B-cell lymphomas. The 1-year actuarial survival rate for B-cell lymphomas (51.9%) was better than that of T-cell lymphomas (0%). However, in Japan the incidence of T-cell PLs was higher, and, partly as a consequence of this, prognosis was poorer than in Western countries.