MRI findings of neuronal ceroid lipofuscinosis in a cat

White, Crystal; Mortier, Jeremy; Verin, Ranieri; Maddox, Thomas; Goncalves, Rita; Sanchez-Masian, Daniel

The cat in this case demonstrated generalised and symmetrical brain cortical atrophy and secondary dilation of the ventricular system and intracranial subarachnoid space (hydrocephalus ex vacuo). These MRI findings have been consistently described in humans and dogs and are considered cardinal signs for neuronal ceroid lipofuscinosis. 10, [16] [17] [18] [19] The cat in this report also showed moderate meningeal thickening. This finding, not described in the human form of the disease, was also reported in three Chihuahuas and a Dachshund with neuronal ceroid lipofuscinosis. 9,20 An autoimmune cause of meningeal thickening has been alluded to; however, in the case of the Dachshund, a subdural haematoma was also identified and the findings of thickened meninges could represent reactive meningitis. In our case, the moderate meningeal thickening was due to the diffuse moderate hypertrophy and fibrosis, and could be interpreted as an adaptive change due to brain atrophy. Hyperostosis of the osseous tentorium cerebelli and calvarium is visible (black arrow). There is mild widening of the cerebellar sulci (<) due to cerebellar atrophy Diffuse T2W white matter hyperintensity with reduction in the white/grey matter distinction has not been previously described in the veterinary literature. A possible explanation for this could be that animals previously reported were scanned with lower field strength MRI magnets. Better contrast resolution of higher field magnets and newer MRI systems could account for this new finding. In humans, periventricular white matter T2W hyperintensity is a common finding in neuronal ceroid lipofuscinosis, confirmed as gliosis and demyelination on histology. In one study, the authors also described a diffuse increase in T2W signal intensity of the white matter. 21 Our patient showed a thinned and partially visualised corpus callosum, which, in this case, likely resulted from the generalised brain atrophy. Atrophy of the corpus callosum has also been described in dogs and humans with neuronal ceroid lipofuscinosis. 18, 22 The cat in our report had generalised calvarial hyperostosis. No skeletal abnormality has been previously described in the human or animal form of the disease. We believe calvarial hyperostosis developed in response to the chronic ex vacuo negative pressure induced by the brain cortical atrophy. Gross and histopathological findings were consistent with previous cases of neuronal ceroid lipofuscinosis in cats, [1] [2] [3] [4] and confirmed the presence of lysosomal storage neuronal disease with autofluorescent material. TEM showed the presence of characteristic small curvilinear lamellar stacks and electron-dense granular material, consistent morphologically with previously described intra-neuronal lipofuscins in cats, making the diagnosis of neuronal ceroid lipofuscinosis highly likely in this case. Ultrastructural intraneuronal deposits consistent with lipofuscins in cats have been described as granular osmophilic deposits (electron-dense granules), curved lamellar stacks and fingerprint profiles, although this latter, ultrastructural organisation was not observed in our case.