  The luminous blue variable (LBV) phase is a poorly understood stage in the
evolution of high mass stars, characterized for its brevity and instability.
The surroundings of LBV stars are excellent test beds to study their dense
stellar winds and eruptive mass-loss events. Aiming to improve our knowledge of
the LBV phase, we observed the J=1-0 and J=2-1 lines of CO and $^{13}$CO in a
field of 1.5'x1.5' around the recently identified candidate LBV MGE
042.0787+00.5084, using the IRAM 30-m radio telescope. We report the first
detection of molecular emission associated with this source, tracing a
structure with an evident circumstellar distribution. Morphology and kinematics
of the gas can be explained by an expanding torus, a structure that may have
originated from stellar ejecta or the action of stellar winds onto the parent
molecular cloud. We derive the physical properties of the gas by means of LTE
and non-LTE line modelling, obtaining densities of H$_2$ in the order of 10$^3$
cm$^{-3}$ and kinetic temperatures below 100 K. In addition, we build a
kinematic model to reproduce the structure and observed velocity fields of the
gas, which is in good agreement with the observations. We estimate a total
molecular gas mass of 0.6$\pm$0.1 Msun and a dynamical age of 6$\times$10$^4$
years, leading to an average mass-loss rate of 0.8-1.2$\times$10$^{-5}$ Msun
yr$^{-1}$.
