ALK and anaplastic large cell lymphoma: ALCL is classified into four subtypes: systemic anaplastic lymphoma kinase-positive ALCL (ALK-positive ALCL), systemic anaplastic lymphoma kinase-negative ALCL (ALK-negative ALCL), primary cutaneous ALCL (pc-ALCL), and breast implant-associated ALCL (BIA-ALCL) [1].