Teaching Case

A 19-year-old female patient presented to the emergency department with progressive-oppressive occipital headache accompanied by vomiting and decreased visual acuity. Patient underwent partial surgical resection.

Sagittal T1WI shows a heterogeneous and enlarged left cerebellar hemisphere with brainstem compression and transtentorial herniation. T2WI and FLAIR images demonstrate an unilateral mass with a folial pattern characterised by alternating bands of different signal intensity. There is also a hyperintense subcortical white matter in the left cerebellum. On the post-contrast T1WI there is no parenchymal enhancement, but we can see the deep running veins between the folia.
All images also demonstrate mass effect with partial collapse of the fourth ventricle.

Lhermitte-Duclos disease, also called dysplastic cerebellar gangliocytoma, manifests without gender predilection in young individuals [1, 2].
Most patients' symptoms stem from increased intracranial pressure and hydrocephalus [1, 3]. A slowly progressive cerebellar syndrome (40%), megalencephaly (50%) and mental retardation are less common clinical features [1].
A strong association between dysplastic cerebellar gangliocytoma and Cowden disease has been described, since both conditions are related to mutations with PTEN tumour suppressor gene located on chromosome 10q22-23. Mutation results in deregulated hyperproliferation of cells, and subsequently oncogenic transformation [4, 5]. Cowden disease is a phacomatosis characterised by multiple hamartomas and an increased risk of breast, thyroid and endometrial carcinomas [6].
The exact nature of this lesion remains unclear, but most authors tend to consider Lhermitte-Duclos disease as a hamartomatous lesion [7].
On a CT examination, dysplastic cerebellar gangliocytoma presents as a low-density cerebellar mass, which may contain calcification and does not show enhancement [5].
At MRI, Lhermitte-Duclos disease reveals most frequently as a left hemispheric cerebellar mass with folial or “tiger-striped” pattern. This tumour is typically hyperintense on T2WI with characteristic alternating bands of different signal intensity relative to gray matter [1, 4, 6]. Most cases demonstrate little or no enhancement, although patchy enhancement of the tumour has been described in some series [6, 7] probably related to the deep running veins between the folia seen on SWI [4].
Treatment of choice is surgery offering good clinical results. With some patients, especially those with partial resections, recurrence has been described even after prolonged periods free of disease [1]. In symptomatic patients it may be necessary to place a ventricular shunt catheter to treat hydrocephalus [1].
The lesion is a low-grade WHO-grade 1 tumour [4]. Histological analysis reveals destruction of the laminar cytoarchitecture of the cerebral cortex with hypertrophy of the molecular layer, as well as dysplastic and hypertrophic neurons in the inner granular layer [5]. Mitosis, atypia or pleomorphism has not been observed in these cell populations [5, 7].