Anaplastic lymphoma kinase-positive large B-cell lymphoma: a distinct clinicopathological entity.

Anaplastic lymphoma kinase-positive large B-cell lymphoma (ALK(+) LBCL) represents a distinct subtype of mature B-cell neoplasms in the most recent WHO classification of hematolymphoid neoplasms. It has a characteristic immunoblastic/plasmablastic morphology, a distinct immunophenotypic profile and recurrent cytogenetic/molecular genetic abnormalities, and has been reported in both the adult and pediatric populations. With the advent of new ALK inhibitors for possible targeted therapy clinical trials, it is important to recognize this new entity, particularly in the pediatric population because the prognosis is worse than the more common ALK+ anaplastic large cell lymphoma. Though rare, awareness of its existence will avoid potential misdiagnosis and facilitate appropriate management.