<h4>Background</h4>The t (2; 5) chromosomal rearrangement of the ALK gene with nucleophosmin 1 gene (NPM1), resulting in an NPM1-ALK fusion, was first demonstrated in 1994 in anaplastic large cell lymphoma, (ALCL), a T-cell lymphoma responsive to cyclophosphamide, abriblastine, vincristine and prednisone in approximately 80% of cases; refractory cases usually respond favorably to brentuximab vedotin. The gene discussed is NPM1; the disease is anaplastic large cell lymphoma.