A midline brain-in-brain malformation was recently reported, but appropriate classification of this malformation remains uncertain. We describe a child with a complex brain malformation that was not restricted to the midline structures, enlarging the neuroanatomical spectrum of this pseudotumoral midline dysplasia associated with corpus callosum dysgenesis, azygos anterior cerebral artery, absent septum pellucidum and bilateral perirolandic cortical abnormalities. The spectrum of fusion of the cerebral hemispheres and associated brain hemispherical abnormalities is not completely understood. Our data are in line with previous arguments that this malformation could be an additional variant in the spectrum of holoprosencephaly.