Dr. Sarnat of the University of Calgary has no relevant financial relationships to disclose.)
This article includes discussion of dysplastic gangliocytoma of the cerebellum, diffuse hypertrophy of the cerebellar cortex, gangliocytoma myelinicum diffusum, gangliomatosis of the cerebellum, ganglioneuroma, granule cell hypertrophy of the cerebellum, granulomolecular hypertrophy of the cerebellum, hamartoma of the cerebellum, Lhermitte-Duclos disease, LDD, myelinated neurocytoma, purkinjeoma, Cowden disease, medulloblastoma, phakomatoses, and PTEN mutations. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Dysplastic gangliocytoma, or Lhermitte-Duclos disease, is a rare cerebellar lesion that is described as neoplastic by some and hamartomatous by others (Nowak and Trost 2002). It is comprised of abnormally enlarged cells primarily in the granule cell layer. It can be associated with Cowden disease, another hamartomatous/neoplastic syndrome. Molecular studies reveal a number of dysplastic gangliocytomas to be associated with germline mutations of the PTEN gene. The author discusses the hamartomatous nature of this entity and recent molecular findings.
• Lhermitte-Duclos is a rare, slow growing cerebellar mass composed of dysplastic ganglion cells.
• Treatment is generally surgical, if clinically indicated; recurrences are not uncommon.
• With MRI, the lesion has a distinctive striated pattern of hyperintensity on T-2 weighted images.
• Lhermitte-Duclos disease is one of the major criteria for the clinical diagnosis of Cowden disease.
Historical note and terminology
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 tumor of ganglion cells arising in a congenital malformation of the cerebellum (Lhermitte and Duclos 1920). The eponym bears their names: "Lhermitte-Duclos disease." The first six cases of Lhermitte-Duclos disease were described from autopsy specimens, and the first surgically removed specimen was taken in 1937 (Faillot et al 1990).
The perplexing and not well understood pathogenesis of this lesion is reflected in the many names given to it over the years: "ganglioneuroma," "dysplastic gangliocytoma," "Purkinjeoma," "hamartoma of the cerebellum," "granule cell hypertrophy," “granulomolecular hypertrophy of the cerebellum,” and "Lhermitte-Duclos disease." According to the 2016 World Health Organization Classification of Tumors of the Central Nervous System, the currently preferred name for this disease is either “dysplastic cerebellar gangliocytoma” or “Lhermitte-Duclos disease.”
Most cases reported in the literature have called the lesion a neoplasm, malformation, or dysplastic hamartoma. After Lhermitte and Duclos' description, Duncan and Snodgrass were the first to attribute the lesion of hypertrophy of the granule cells to dysplasia (Duncan and Snodgrass 1943). The question of this lesion being either a neoplasm or dysplastic hamartoma has been addressed repeatedly (Hallervorden 1959). The overwhelming view is that Lhermitte-Duclos disease is a dysplastic hamartoma or malformation (Vinchon et al 1994). Although few authors claim this lesion to be neoplastic, many authors have commented on its growth potential. For the sake of clarification, this author uses the term "Lhermitte-Duclos disease" and considers the entity to be dysplastic in nature, and she avoids the use of terms that may indicate neoplasia. However, if this lesion is considered neoplastic by the treating clinician, it corresponds to a WHO Grade I lesion within the “neuronal and mixed neuronal-glial tumors” category (Eberhart et al 2016).
Ambler noted, as had previous authors, other malformations in patients with the cerebellar lesion and considered the disorder a probable phacomatosis like tuberous sclerosis or Von Hippel-Lindau disease (Ambler et al 1969). She also reported the first familial case of the disorder (a mother and son). Multiple reports associating Lhermitte-Duclos disease and Cowden disease (multiple hamartoma-neoplasia syndrome) have appeared in the literature since 1991 (Padberg et al 1991).
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