  We use Perron's method to construct viscosity solutions of fully nonlinear
degenerate parabolic pathwise (rough) partial differential equations. This
provides an intrinsic method for proving the existence of solutions that relies
only on a comparison principle, rather than considering equations driven by
smooth approximating paths. The result covers the case of multidimensional
geometric rough path noise, where the noise coefficients depend nontrivially on
space and on the gradient of the solution. Also included in this note is a
discussion of the comparison principle and a summary of the pathwise equations
for which one has been proved.
