Anaplastic large-cell Ki-1 malignant lymphomas. Recognition, biological and clinical implications.

Anaplastic large-cell Ki-1 lymphoma is defined by its characteristic histological appearance, reactivity with antibodies against CD30, and possibly by a chromosome marker t(2;5)(p23;q35). Because of its pleomorphic appearance, sinus distribution, and frequent reactivity with EMA, this lymphoma is often mistaken for other diseases such as metastatic carcinoma and malignant histiocytosis. The clinical features of this lymphoma are unusual and include a young median age and frequent extranodal disease with skin being a common site. Although remission is easily achieved, relapse is common and combination chemotherapy is suggested. The role of Ki-1 antigen in normal lymphocyte function, the cell of origin of anaplastic large-cell Ki-1 lymphoma, and its relationship to Hodgkin's disease are important questions that hopefully will be answered in the near future.