We present recent results that show that the singular Liouville equation in the plane can be viewed as a limit of semilinear elliptic equations of Lane-Emden type as the exponent of the nonlinearity becomes very large.This is achieved through the study of the asymptotic behavior of families of sign changing solutions whose nodal line does not touch the boundary.In particular this phenomenum arises while studying radial sign changing solutions of Lane Emden problems.An accurate study of the spectrum of the linearized operator shows a relation between the Morse index of these solutions and that of a specific solution of the limit problem.As a consequence we get the existence of new nonradial sign changing solutions in the ball.The results are contained in some papers in collaboration with F.De Marchis-I.Ianni and M.Grossi-C.Grumiau.