  Quasar microlensing effects make it possible to measure the accretion disc
sizes around distant supermassive black holes that are still well beyond the
spatial resolution of contemporary instrumentation. The sizes measured with
this technique appear inconsistent with the standard accretion disc model. Not
only are the measured accretion disc sizes larger, but their dependence on
wavelength is in most cases completely different from the predictions of the
standard model. We suggest that these discrepancies may arise not from
non-standard accretion disc structure or systematic errors, as it was proposed
before, but rather from scattering and reprocession of the radiation of the
disc. In particular, the matter falling from the gaseous torus and presumably
feeding the accretion disc may at certain distances become ionized and produce
an extended halo that is free from colour gradients. A simple analytical model
is proposed assuming that a geometrically thick translucent inflow acts as a
scattering mirror changing the apparent spatial properties of the disc. This
inflow may be also identified with the broad line region or its inner parts.
Such a model is able to explain the basic properties of the apparent disc
sizes, primarily their large values and their shallow dependence on wavelength.
The only condition required is to scatter significant portion of the luminosity
of the disc. This can easily be fulfilled if the scattering inflow has large
geometrical thickness and clumpy structure.
