  We evaluate a zero-point quantum correction to a Belavin-Polyakov soliton in
an isotropic 2D ferromagnet. By revising the scattering problem of
quasi-particles by a soliton we show that it leads to the Aharonov-Bohm type of
scattering, hence the scattering data can not be obtained by the Born
approximation. We proof that the soliton energy with account of quantum
corrections does not have a minimum as a function of its radius, which is
usually interpreted as a soliton instability. On the other hand, we show that
long lifetime solitons can exist in ferromagnets due to an additional integral
of motion, which is absent for the sigma-model.
