CD56‐expression in bone marrow or other relevant tissue samples related to histopathological diagnosis and clinical outcome in children

In normal bone marrow CD56‐expression is low, but in acute leukemia or lymphoma in adults a marked increase in CD56‐expression is associated with a worse clinical outcome. In children, however, it is unclear whether a high CD56‐expression relates to the histopathological diagnosis and prognosis. In a five‐year period (2000‐05) we retrospectively assessed medical files of children below 15 years of age. As established by flowcytometry, bone marrow or other relevant tissue samples with a percentage of CD56+ cells higher than 10% were selected. Ten patients (age 5.1 ± 1.2 yr; mean ± SEM) were included and in most patients CD56+ analysis was performed at the time of diagnosis. Six patients had acute myeloid leukemia (AML) (66 ± 11% cells expressing CD56) and the remaining four patients were with cutaneous lymphoma (20%), myeloid sarcoma in pleura (40%), juvenile myelomonocytoid leukemia (27%) or large cell anaplastic T‐cell lymphoma (13%), respectively. Two patients with AML and the patient with myeloid sarcoma in pleura died 11 ± 3 months after the diagnosis was established and the %CD56+ cells was 66 ± 13 as compared to 43 ± 12 in the remaining seven children who are still alive (follow‐up time 28 ± 11 months). In this group one patient relapsed during treatment. Our cases with a high expression of CD56+ cells relates to a wide range of diagnosis. As in adults the data suggests that in children the expression of CD56 in acute leukemia is associated with a bad outcome.