Ki-1 Positive Anaplastic Large Cell Lymphoma Due to Immune Deficiency.

Cases of Ki-1 positive anaplastic large cell lymphoma (ALCL), including ALK (t 2,5) positive and negative expression, have largely been associated with immunosuppressed transplant recipients, human immunodeficiency virus (HIV) positive patients and patients with a prior history of a lymphoproliferative disorder. We reviewed the literature and found cases of secondary Ki-1 positive ALCL in immunocompromised patients including patients with a prior history of lymphoid malignancy. Some of these latter cases may have been diagnosed initially as Hodgkin’s disease and later reclassified as Ki-1 positive ALCL. In post-transplant and HIV positive patients, severe and prolonged immunosuppression likely led to the development of Ki-1 positive ALCL. We postulate that although rare, the occurrence of Ki-1 positive ALCL in patients previously treated for a lymphoid malignancy is possible due to a pre-existing immune deficiency state. We report a case of ALK- ALCL occurring 10 years following treatment of HCL with persistent depressed T4/T8 ratio one year after achieving a complete remission of the ALCL.