In 1985, Stein et al. (Blood 66:848-858) described a large cell lymphoma consisting of activated lymphoid elements, expressing the Reed-Sternberg cell-associated antigen Ki-1 (CD30); this tumor has recently been included in the updated Kiel classification and has been termed anaplastic large cell lymphoma (ALCL). This report concerns 13 patients with previously untreated ALCL who were admitted to the Pediatric Hematology and Oncology Department of Bologna University between January 1983 and December 1989. Ten cases were diagnosed as common type ALCL, 1 as Hodgkin's-related ALCL and the remaining 2 as histiocyte-rich ALCL/lymphohistiocytic T-cell lymphoma. T-cell markers were present in 85% of the cases, and B phenotype in the remaining 15%. About one-half of the patients presented systemic symptoms; all but one showed more than one involved site, mostly an association of nodal and extranodal sites. All patients (1 in stage I, 7 in stage II, and 5 in stage III) were treated with a modified version of the LSA2-L2 protocol. Survival and event-free survival at 4 years were 100% and 62.9%, respectively. Two out of 3 relapsed patients presented a recurrence of disease when they were off-therapy 24 and 36 months after first complete remission. Good response to salvage chemotherapy of all the relapsed patients and the long duration of the second complete remission were a distinctive characteristic of this neoplasm when compared to other histological subtypes. The clinical presentation, the tendency to develop late relapses and to achieve and maintain second remission easily suggest that ALCL is a high grade non-Hodgkin's lymphoma, from the histological point of view, but is similar to Hodgkin's disease from the clinical point of view. This would confirm the hypothesis that Hodgkin's disease and ALCL represent a continuous spectrum of the same disease.