Anaplastic Large Cell Lymphoma

Anaplastic lymphoma kinase positive (ALK+) anaplastic large cell lymphoma (ALCL) is a peripheral T-cell lymphoma (PTCL) that consists of characteristic large pleomorphic lymphoid cells with abundant cytoplasm and horseshoe-shaped nuclei, strongly positive for CD30 immunohistochemical staining. ALK+ ALCL has associated recurrent t(2;5) fusion translocation involving the ALK gene and nucleophosmin (NPM1) gene. Ki-1 lymphoma is the old terminology that refers to the CD30 (previously designated as Ki-1 antigen) positive lymphomas, exhibiting a morphology resembling malignant histiocytes, but having overlapping immunohistochemical features of classic Hodgkin's lymphoma. The 2016 revised World Health Organization (WHO) lymphoma classification includes four distinct entities under ALCL: systemic ALK-positive ALCL (ALK+ ALCL), systemic ALK-negativeALCL (ALK- ALCL), primary cutaneous ALCL (pC ALCL), and the provisional entity breast implant-associated ALCL (BI-ALCL).