  We review and examine in detail recent developments regarding the question of
the nucleon mass decomposition. We discuss in particular the virial theorem in
quantum field theory and its implications for the nucleon mass decomposition
and mechanical equilibrium. We reconsider the renormalization of the QCD
energy-momentum tensor in minimal-subtraction-type schemes and the physical
interpretation of its components, as well as the role played by the trace
anomaly and Poincar\'e symmetry. We also study the concept of "quantum
anomalous energy" proposed in some works as a new contribution to the nucleon
mass. Examining the various arguments, we conclude that the quantum anomalous
energy is not a genuine contribution to the mass sum rule, as a consequence of
translation symmetry.
