Neuropathology of Raine syndrome

We present three cases of Raine syndrome occurring in siblings of consanguineous parents. Raine syndrome is characterised by generalised osteosclerosis with craniofacial anomalies and intracranial calcifications. So far, only nine cases have been reported, and no evaluation of the distribution and extent of the cerebral mineralisations, as well as their impact on the surrounding tissue, has been undertaken yet. In our cases, calcifications were unevenly distributed throughout the central nervous system, not associated with neuronal loss or dystrophic events and appeared mostly as single calcospherites within the neuropil with occasional confluent deposits at advanced gestational age. There was intense perifocal microgliosis around single immature calcospherites, as well as mild astrogliosis around and within the confluent lesions, in which occasional macrophages could be found. Rarely, mineralisations occurred in blood-vessel walls, mainly affecting basal ganglia. Preferential sites of calcification were parietal and occipital periventricular white matter and corpus callosum, while frontal lobes were mildly affected. The cortex, temporal lobes as well as internal capsule, brain stem, cerebellum, leptomeninges, pituitary gland and choroid plexus were devoid of mineralisations. The subcortical grey matter was moderately involved in the putamen and pallidum, mildly in the caudate nucleus and subependymal germ cell matrix and not at all in the thalamus, Ammon's horn, amygdala and substantia nigra. The distribution of mineral deposits was thus inversely correlated to regional blood circulation and capillary density, with calcifications being concentrated in more sparsely perfused areas but lacking in highly vascularised tissue. This inverse relationship between mineralisation and regional blood flow was reflected in the varying distribution of calcospherites in grey and white matter as well as in the white matter of different lobes.