Pediatric CD56+ anaplastic large cell lymphoma: a review of the literature.

CONTEXT: Anaplastic large cell lymphomas (ALCLs) are a heterogeneous group of CD30+ large cell lymphomas that, according to the World Health Organization classification, are defined as being of T-cell origin, based on immunophenotype, and/or the finding of a T-cell gene rearrangement by molecular studies. Most cases express cytotoxic granule-associated proteins. Relatively recent data have suggested that some T-cell ALCLs are derived from cytolytic CD4+ cells, gammadelta T cells, or natural killer-like (CD56+ or CD57+) T cells. We encountered a pediatric case of CD56+, anaplastic lymphoma kinase-positive ALCL of apparent natural killer-like T-cell origin (showing positivity for CD2, cytoplasmic CD3, surface CD3 partial positivity, CD7, CD8, CD56, TIA-1, and granzyme B). The patient had initial lymph node and multiple sites of cutaneous involvement and an aggressive clinical course with multiple recurrences after varying periods of complete remission. OBJECTIVE: To review the current pediatric literature regarding the incidence, differential diagnosis, and clinical course of such cases. DATA SOURCES: Relevant articles indexed in PubMed (National Library of Medicine) between 1975 and 2006. CONCLUSIONS: Our review did not confirm a uniformly aggressive clinical course in pediatric cases of CD56+ ALCLs. Such cases suggest the usefulness of the analysis of CD56-positivity in additional cases of ALCL in an attempt to accrue additional information on this condition. Future accrual of such cases may address whether such cases should be treated more aggressively or with possible targeted therapeutic regimens.