Discussion

Dysplastic cerebellar gangliocytoma, also known as Lhermitte-Duclos disease, typically affects adults in the third and fourth decades of life.  Patients with this disease typically present to a physician for evaluation of progressive ataxia, nausea/vomiting, headache, or other symptoms consistent with increased intracranial pressure, reflecting mass effect on the fourth ventricle.  

MR imaging characteristics consist of a regionally thickened lesion in the posterior fossa with T2 hyperintensity noted within the cerebellar folia without associated contrast enhancement.

Histologically, there is variable replacement of the internal granular cell layer by a disorganized array of large neurons with attendant expansion and aberrant myelination of the overlying molecular layer. The molecular layer may exhibit coarse spongy changes and dystrophic mineralization, often blood vessel-associated. The subjacent foliar white matter is typically thinned, if not cavitated.

This disorder can occur sporadically or as a manifestation of Cowden syndrome. This is an autosomal dominant phakomatosis linked to germline mutations of the PTEN/MMAC 1 gene on chromosome 10q23. Manifestations of this syndrome include multiple cutaneous trichilemmomas, oral papillomatosis, acral keratoses, macrocephaly/megalencephaly, various types of gastrointestinal polyps, thyroid abnormalities, and a substantially increased risk of mammary adenocarcinoma. The dysplastic gangliocytoma of the cerebellum is a hallmark of this syndrome.

These benign lesions are thought to be hamartomatous rather than neoplastic in nature by some authors, and their growth may be related to hypertrophy rather than replication. Gross total resection is the treatment of choice. Despite this treatment, recurrences have been recorded. The prognosis, however, is generally excellent.

References:

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