ALK-positive anaplastic large cell lymphoma with prominent bone involvement in a 13-year-old boy.

Introduction Anaplastic lymphoma kinase-positive (ALK+) anaplastic large cell lymphoma (ALCL) is a type of non-Hodgkin lymphoma, which has strong expression of cluster of differentiation (CD)-30 and ALK. ALCL sometimes can involve the bone marrow, and in advanced stages, it can produce destructive bone lesions. But ALK+ ALCL with prominent bone involvement is very rare, especially in children.