  An anomaly in the distribution of quasar magnitudes based on the SDSS survey,
has been recently reported by Longo (2012). The angular size of this anomaly is
of the order of $\rm \pm 15^o$ on the sky. A low surface brightness smooth
structure in $\gamma$-rays, coincides with the sky location and extent of the
quasar anomaly, and is close to the Northern component of a pair of
$\gamma$-ray bubbles discovered in the \sl Fermi Gamma-ray Space Telescope \rm
survey. Molecular clouds are thought to be illuminated by cosmic rays. I test
the hypothesis that the magnitude anomaly in the quasar distribution, is due to
a lensing effect by an hypothetic Supergiant Molecular Cloud (SGMC) in the
Galactic halo.A series of grid lens models are built by assuming firstly that a
SGMC is a lattice with clumps of $\rm 10^{-3} M_\odot$, 10 AU in size, and
assuming various filling factors of the cloud, and secondly a fractal
structure. Local amplifications are calculated for these lenses by using the
public software LensTool, and the single plane approximation. A complex network
of caustics due to the clumpy structure is present. Our best single plane lens
model capable of explaining Longo's effect, \sl at least in sparse regions, \rm
requires a mass $\rm (1.5-4.1) \times 10^{10} ~M_\odot$ within $\rm 8.7 \times
8.7 \times (5-8.6) kpc^3$ at a lens plane distance of 20 kpc. It is constructed
from a molecular cloud building block of $5 \times 10^5 M_\odot$ within a scale
of 30 pc expanded by fractal scaling with dimension $D = 1.8-2$ up to 5-8.6 kpc
for the SGMC. If such a Supergiant Molecular Cloud were demonstrated, it might
be part of a lens explanation for the luminous anomaly discovered in quasars
and in red galaxies. The mass budget may be varied by changing the cloud depth
and the fractal dimension.
