We consider nonhomogeneous, degenerate (m > 1) porous medium type equations with a nonnegative Radon measure \mu having finite total mass \mu(E_T ) on the right-hand side, and we derive linear pointwise estimates for solutions via Riesz potentials. Then, we deal with a Cauchy-Dirichlet problem for the same equation, with homogeneous boundary conditions on the parabolic boundary of the domain E_T, and we establish the existence of a solution in the sense of distribution