[T-cell prolymphocytic leukemia complicated by diffuse large B-cell lymphoma of the stomach]

We describe a case of T-cell prolymphocytic leukemia (T-PLL) in a 76-year-old man, who developed diffuse large B-cell lymphoma (DLBL) of the stomach, a previously unreported occurrence. The patient was referred to our hospital because of marked leukocytosis (40,000/microliter) without clinical symptoms. He was diagnosed as having T-PLL on the basis of the characteristic cell morphology and immunophenotype (CD2+, CD3+, CD4+, CD5+, CD7+, CD8-, CD25-, TCR alpha/beta+), but cytogenetic analysis showed no abnormalities. Fifteen months later, he developed a gastric tumor. Biopsy of the tumor revealed DLBL without features of MALT lymphoma; Helicobacter pylori was not detected. Chemotherapy eradicated the tumor, whereas the T-PLL was resistant to the therapy. The disease showed an indolent course for about 2 years thereafter. Immunological derangement due to T-PLL might have potentiated the development of DLBL in this case.