Anaplastic large cell lymphoma (ALCL) is a fast-growing non-Hodgkin lymphoma (NHL) and accounts for 10–15% of pediatric and adolescent NHL; ALCL in pediatric patients is almost always ALK-positive and mutant cells show the t(2;5)(p23;q35) translocation, constitutively expressing the NPM-ALK fusion protein [91]. The gene discussed is NPM1; the disease is anaplastic large cell lymphoma.