Conclusion: We have described a case of pancreatic tumor formed by adult T-cell leukemia (ATL) cell infiltration.
Background: The patient was diagnosed as chronic ATL hematologically with the findings of increased number of atypical lymphocytes, ATL cells in the peripheral blood, and positive human T-cell leukemia virus type I (HTLV-I) antibody in the serum. The pancreatic tumor was identified by ultrasonography and computed tomography as a diffusely swollen tumor from the body to the tail of the pancreas. Biopsy specimen confirmed the ATL cell infiltration into the pancreas immunohistochemically, and Southern blot analysis showed the integration of HTLV-I proviral DNA both in the pancreas and in the peripheral blood.
Results: The pancreatic tumor diminished spontaneously without chemotherapy when ATL cells in the peripheral blood disappeared by spontaneous regression.