Clinicopathological study of Ki-1-positive lymphomas

We examined an antibody against Ki-1 antigen in 161 cases of malignant lymphoma, four of histiocytic sarcoma, and six of nonspecific lymphadenitis, using monoclonal antibody Ki-1, which is known to react selectively with activated lymphocytes, Reed-Sternberg cells, and Hodgkin's cells. Among them, 12 cases of malignant lymphoma demonstrated a diffuse positive cell membrane and/or cytoplasmic reaction of tumor cells and were categorized as Ki-1-positive lymphoma. Nine of these cases exhibited large cells with indented nuclei, distinct nucleoli, and abundant basophilic or amphophilic cytoplasm. Of the remaining three cases, two were of medium-sized and one of small-cell type. Immunologically, the 12 cases of malignant lymphoma demonstrated T-helper/inducer phenotype in six cases, B-cell in two case, and non-T, non-B in four cases. Tac and HLADR were positive in 9/12 and 4/5, respectively, and markers for histiocytes (lysozyme, alpha-1 anti-chymotrypsin, and OK-M1) were usually negative. Clinically, T-cell Ki-1-positive lymphoma was most likely to occur in the elderly, at extranodal sites, and had a rather poor prognosis (mean survival 35.5 months) as compared with B-cell and non-T, non-B lymphoma (7-52 months survival).