  Using Keck/NIRC2 $L^\prime$ (3.78 $\mu m$) data, we report the direct imaging
discovery of a scattered light-resolved, solar system-scale residual
protoplanetary disk around the young A-type star HD 141569A, interior to and
concentric with the two ring-like structures at wider separations. The disk is
resolved down to $\sim$ 0\farcs{}25 and appears as an arc-like rim with
attached hook-like features. It is located at an angular separation
intermediate between that of warm CO gas identified from spatially-resolved
mid-infrared spectroscopy and diffuse dust emission recently discovered with
the \textit{Hubble Space Telescope}. The inner disk has a radius of $\sim$ 39
AU, a position angle consistent with north-up, an inclination of $i$ $\sim$
56$^{o}$, and has a center offset from the star. Forward-modeling of the disk
favors a thick torus-like emission sharply truncated at separations beyond the
torus' photocenter and heavily depleted at smaller separations. In particular,
the best-fit density power law for the dust suggests that the inner disk dust
and gas (as probed by CO) are radially segregated, a feature consistent with
the dust trapping mechanism inferred from observations of "canonical"
transitional disks. However, the inner disk component may instead be explained
by radiation pressure-induced migration in optically-thin conditions, in
contrast to the two stellar companion/planet-influenced ring-like structures at
wider separations. HD 141569A's circumstellar environment --- with three
nested, gapped, concentric dust populations --- is an excellent laboratory for
understanding the relationship between planet formation and the evolution of
both dust grains and disk architecture.
