We offer the Skyrme model on a lattice as an effective field theory-fully q
uantized-of baryon-meson interactions at temperatures below the chiral phas
e transition. We define a local topological density that involves the volum
es of tetrahedra in the target space S-3 and we make use of Coxeter's formu
la for the Schlafli function to implement it. This permits us to calculate
the mean-square radius of a Skyrmion in the three-dimensional lattice Skyrm
e model, which may be viewed as a Ginzburg-Landau effective theory for the
full quantum theory at finite temperature. We find that, contrary to expect
ations, the Skyrmion shrinks as quantum and thermal fluctuations are enhanc
ed. We ascribe this to a large number of metastable states th:lt become acc
essible as the temperature is raised.