[Patient with B-CLL with a history of unrelated hematopoietic cells donation--retrospective analysis of CLL development and implication for the recipient].

BACKGROUND Donor cell leukemia (DCL) is a relatively rare but well documented complication of hematopoietic stem cell transplantation. So far, publications described only DCL arising de novo in the recipient. OBSERVATION In this study, we describe a case of chronic lymphocytic leukemia (B-CLL) developing in a volunteer unrelated donor from the Czech National Marrow Donors Registry (CNMDR) several years after donation. From archival DNA sample, we have retrospectively found that subclinical CLL clone was already present at the time of donation but early death of recipient prevented eventual development of DCL. This case documents well the long period between detection of B-CLL clone and full development of clinical-laboratory symptomatology. The medical and ethical questions posed by an isolated case of detection of hematological malignancy present either only in the donor or only in the recipient are discussed. CONCLUSION The case demonstrates the increasing risk of development of various forms of DCL and thus highlights the need for long-term monitoring of stem cell donor, not only in terms of health of donor but also in terms of potential risks for the recipient.