CD5 and anaplastic large cell lymphoma: The loss of several T cell markers including CD3, CD2, CD5, CD7 and the T cell antigen receptor (TCR) is a common feature of ALK+ ALCL cells, leading to an apparent “null cell” phenotype that may be used for the differential diagnosis with other CD30+ PTCL or CD30+ mycosis fungoides with large cell transformation [4,13,14].