To evaluate this entity in a pediatric population, 36 cases of childhood large cell lymphoma were evaluated for abnormalities of the anaplastic lymphoma kinase (ALK) gene that has been associated with ALCL morphology and immunophenotype.
The aggregate results of these studies indicate that the t(2;5) translocation or other somatic mutations resulting in inappropriate expression of ALK are involved rarely if at all in the pathogenesis of Hodgkin's disease, but may be present in about 10% of cases of lymphomatoid papulosis and 20% of cases of CD30+ primary cutaneous large cell lymphoma.
This translocation creates a novel fusion protein, NPM-ALK, which has transforming properties in vitro and can cause large-cell lymphoma in vivo when transfected into murine bone marrow.
In aggregate, these results strongly suggest that inappropriate expression of ALK is not involved in the pathogenesis of these CD30+ lymphoproliferative disorders, and that lymph node-based CD30+ large cell lymphoma is a disease that is biologically distinct from skin-based CD30+ lymphoproliferative disorders and Hodgkin's disease.