  We consider the effect of volume fluctuations on cumulants of the net baryon
number. Based on a general formalism, we derive universal expressions for the
net baryon number cumulants in the presence of volume fluctuations with an
arbitrary probability distribution. The relevance of these fluctuations for the
baryon-number cumulants and in particular for the ratios of cumulants is
assessed in the Polyakov loop extended quark-meson model within the functional
renormalization group. We show that the baryon number cumulants are generally
enhanced by volume fluctuations and that the critical behavior of higher order
cumulants may be modified significantly.
