  We study the compatibility of large quasar groups with the concordance
cosmological model. Large Quasar Groups are very large spatial associations of
quasars in the cosmic web, with sizes of 50-250h^-1 Mpc. In particular, the
largest large quasar group known, named Huge-LQG, has a longest axis of
~860h^-1 Mpc, larger than the scale of homogeneity (~260 Mpc), which has been
noted as a possible violation of the cosmological principle. Using mock
catalogues constructed from the Horizon Run 2 cosmological simulation, we found
that large quasar groups size, quasar member number and mean overdensity
distributions in the mocks agree with observations. The Huge-LQG is found to be
a rare group with a probability of 0.3 per cent of finding a group as large or
larger than the observed, but an extreme value analysis shows that it is an
expected maximum in the sample volume with a probability of 19 per cent of
observing a largest quasar group as large or larger than Huge-LQG. The Huge-LQG
is expected to be the largest structure in a volume at least 5.3 +- 1 times
larger than the one currently studied.
