  We assess the evolutionary status of the intriguing object Walker 90/V590
Mon, which is located about 20 arcminutes northwest of the Cone Nebula near the
center of the open cluster NGC 2264. This object, according to its most recent
optical spectral type determination (B7), which we confirmed, is at least 3
magnitudes too faint in V for the cluster distance, but it shows the classical
signs of a young pre-main sequence object, such as highly variable Halpha
emission, Mg II emission, IR excess, UV continuum, and optical variability. We
analyzed a collection of archival and original data on Walker 90, covering 45
years including photometry, imaging, and spectroscopic data ranging from
ultraviolet to near-infrared wavelengths. According to star formation
processes, it is expected that, as this object clears its primordial
surroundings, it should become optically brighter, show a weakening of its IR
excess and present decreasing line emissions. This behavior is supported by our
observations and analysis, but timescales are expected to be longer than the
one observed here. Based on photometric data secured in 2007, we find Walker 90
at its brightest recorded optical magnitude. We document an evolution in
spectral type over the past five decades (from A2/A3 to currently B7 and as
early as B4), along with a decrease in the near-infrared K fluxes. From
near-infrared images secured in 2004, Walker 90 appears as a point source
placing an upper limit of 0.1 arcsec for its diameter. We conclude that many
observational features are explained if W90 is a flared disk system, surrounded
by an inclined optically thick accretion disk.
