  The massive star forming region W49A represents one of the largest complexes
of massive star formation present in the Milky Way and contains at least fifty
young massive stars still enshrouded in their natal molecular cloud. We employ
Spitzer/IRS spectral mapping observations of the northern part of W49A to
investigate the mid-infrared (MIR) spatial appearance of the polycyclic
aromatic hydrocarbon (PAH) bands, PAH plateau features, atomic lines and
continuum emission. We examine the spatial variations of the MIR emission
components in slices through two of the ultra compact-HII (UC-HII) regions. We
find that the PAH bands reproduce known trends, with the caveat that the 6.2
$\mu$m PAH band seems to decouple from the other ionized PAH bands in some of
the UC-HII regions -- an effect previously observed only in one other object:
the giant star forming region N66 in the LMC. Furthermore, we compare the
nature of the emission surrounding W49A to that of `diffuse' sightlines. It is
found that the surrounding emission can be explained by line of sight emission,
and does not represent true `diffuse' material. Additionally, we examine the
MIR appearance of star formation on various scales from UC-HII regions to
starburst galaxies, including a discussion of the fraction of PAH emission in
the 8 $\mu$m IRAC filter. We find that the MIR appearance of W49A is that of a
starburst on large scales yet its individual components are consistent with
other galactic HII regions.
