  We develop the pQCD description of diffraction excitation of heavy flavours
in DIS and we derive the analytic formulas for the mass spectrum in leading
log$m_f^{2}$. The result illustrates nicely non-factorization properties of the
QCD pomeron. We predict a very steep rise of the charm content of diffraction
dissociation of photons at small $x_{\Pom}$. We evaluate the contribution of
open charm to scaling violations in the structure function of the pomeron.
