Teaching Case

A 33-year-old woman presented with progressive headache and ataxia.

MR imaging examination on 1.5 T system, coil dedicated, on the axial, coronal and sagittal planes, using SE T1W, DWI, FSE T2W, FLAIR T1W/T2W, STIR, PROBE and PRESS sequences, were performed.
Magnetic resonance imaging (MRI) revealed an enlarged right cerebellum with alternate bands of hypo and hyper intensities ('tiger-striped' appearance) on T2 weighted images. There was bright signal within the mass on diffusion-weighted images. There was no contrast enhancement and there was also tonsillar herniation. Because of the small size of these lesions, it is unlikely that tonsillar bilateral herniation is due to mass effect, rather to the probable posterior fossa congenital volume reduction. MR spectroscopy showed slightly reduced levels of metabolites. This MRI findings are compatible with a very probable case of dysplastic gangliocytoma of the cerebellum.

Dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos disease) (LDD) is a rare condition featured by disorganized cerebellar folia leading to characteristic thickening of the cerebellar folia. It has features of both malformation and neoplasm. The first description of a novel disorder of the cerebellum, characterized by enlarged folia with abnormal ganglion cells, was made by J. Lhermitte and P. Duclos in 1920. They referred to it as a cerebellar neurinoma, a tumour of ganglion cells arising in a congenital malformation of the cerebellum. LDD is discovered typically in the 3rd and 4th decades and is associated with Cowden syndrome and linked to germline mutations in PTEN gene [1]. The most common manifestations are those related to obstructive hydrocephalus and intracranial hypertension. Other manifestations include cerebellar signs such as ataxia and deficits of cranial nerves. They may also be incidental findings. The salient macroscopic feature of LDD on cross section is thickening of the folia. On MRI images, this pattern is transformed into a pathognomonic "tiger-stripping" laminations of alternating T1/T2-isointense and T1-hyperintense/T2-hypointense laminations in reference to cerebellar grey matter [2]. This pattern can also be recognized by high resolution CT. No contrast enhancement for most cases. Treatment is not needed in the asymptomatic patient. The dysplastic mass grows very slowly, and initial treatment revolves around treating hydrocephalus. Surgical resection is often curative [3].