Activating ALK alterations—comprising gain-of-function point mutations, high-level gene amplifications, and oncogenic fusions/rearrangements—have been documented in a spectrum of malignancies that includes NSCLC, anaplastic large-cell lymphoma (ALCL; accounting for approximately 0.5% of adult lymphomas and roughly 10% of pediatric non-Hodgkin lymphomas), IMT, neuroblastoma, cutaneous spitzoid neoplasms, and inflammatory breast carcinoma. The gene discussed is ALK; the disease is anaplastic large cell lymphoma.