Late relapse from complete remission in nodular and diffuse histiocytic lymphoma.

Twelve patients with unfavorable prognosis lymphomas (diffuse histiocytic lymphoma, 11; nodular histiocytic lymphoma, 1) treated predominantly with radiation therapy, are described in whom relapse of disease occurred late (greater than 2.5 years, 2.8-26 years; median, 6.25 years) after achieving a complete remission. Although relapse probably represented regrowth of clinically quiescent tumor, it is also possible that these were second malignancies, perhaps occurring in a predisposed host. Continued long-term analysis of clinical trials is important to document this uncommon occurrence.