  The van Stockum-Bonner class of spacetimes can be interpreted as fully
general relativistic models for rigidly rotating disc galaxies. Frame-dragging
effects in these geometries demand a recalibration of the dark matter content
relative to models based on Newtonian gravity. We investigate the previously
overlooked topological structure of these spacetimes, in relation to the
viability of fully general relativistic galaxy toy models. We discuss the
appropriate boundary conditions for these solutions to model disc galaxies. For
this class of spacetimes, we show the existence of a network of quasi-regular
singularities along the rotation axis of the galaxies. The existence of such
novel conical defect structures further restricts the physical viability of the
van Stockum-Bonner class. Unwinding these issues is key to avoiding pathologies
in future fully general relativistic modelling of alternative to dark matter.
