Dysplastic cerebellar gangliocytoma, perhaps better known as Lhermitte-Duclos disease, is a rare tumor of the cerebellum appearing as thickening and increase in T2 signal of the cerebellar folia giving this lesion a characteristic striated appearance.
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Epidemiology
Dysplastic cerebellar gangliocytomas typically present in young adults, although they have been encountered at all ages 3,6.
Associations
A number of associated conditions have been described 1,3, including:
Cowden syndrome (as part of COLD syndrome, see below)
Clinical presentation
Small tumors may be asymptomatic or only present with relatively subtle cerebellar signs (e.g. dysmetria). When larger, symptoms are typically related to raised intracranial pressure, obstructive hydrocephalus and to a lesser degree, cerebellar dysfunction 3.
Pathology
Dysplastic cerebellar gangliocytomas are designated as WHO grade 1 tumors and considered one of a number of glioneuronal and neuronal tumors in the WHO classification of CNS tumors 9.
Genetics
Interestingly the genetics of childhood-onset appears different from the more common adult-onset form. In the adult form, PTEN mutations are invariably found, lending additional weight to Lhermitte-Duclos disease being a manifestation of Cowden syndrome. In such cases, it is termed COLD syndrome (Cowden-Lhermitte-Duclos syndrome) 7. In contrast, in children, PTEN mutations are absent 6.
Macroscopic appearance
Dysplastic cerebellar gangliocytomas are usually single and unilateral, presenting as a discrete region of cerebellar hypertrophy 6.
Microscopic appearance
Derangement of the normal laminar cellular organization of the cerebellum is present. There is thickening of the outer molecular cell layer, loss of the middle Purkinje cell layer, and infiltration of the inner granular cell layer with dysplastic ganglion cells of various sizes 6.
Immunophenotype
synaptophysin: positive
loss of PTEN protein expression (Cowden syndrome/COLD syndrome)
Radiographic features
The abnormal tissue involves the cerebellar cortex and is usually confined to one hemisphere, occasionally extending to the vermis but only rarely extending to the contralateral hemisphere 1.
CT
may show a non-specific hypoattenuating cerebellar mass
calcification is sometimes seen 2,5
MRI
Widened cerebellar folia with a striated/tigroid appearance. Also described as "corduroy/laminated" appearance 8.
T1: hypointense 2
T2: hyperintense with apparently preserved cortical striations 1
-
DWI: similar to normal cortex
may show hyperintensity due to T2 shine-through effect
-
T1 C+ (Gd)
enhancement is rare
if present usually superficial, possibly due to vascular proliferation 4
-
MR spectroscopy
elevated lactate 1,2
slightly reduced NAA (by about 10%) 1,2
reduced myo-inositol (by 30-80%)
reduced choline (by 20-50%)
reduced Cho/Cr ratio 2
PET/SPECT
FDG-PET: increased uptake
Tl-201 SPECT: increased uptake
Treatment and prognosis
The dysplastic mass grows very slowly, and initial treatment revolves around treating hydrocephalus. Surgical resection is often curative, with only a few case reports of recurrence 3. Importantly it is crucial to remember the association with Cowden syndrome, hence, increased risk of other neoplasms such as breast, endometrial and thyroid cancers. Therefore, a recommendation for further imaging or clinical assessment of possible tumors in these locations should be included in the radiologist's report.
History and etymology
It is named after the French neurologist and neuropsychiatrist Jacques Jean Lhermitte (1877-1959), with his physician colleague P Duclos, who jointly described the condition in 1920 6.
Differential diagnosis
The appearance is very characteristic and usually little differential exists, particularly when appearances are typical.
In the setting of sepsis or acute deterioration, one should consider cerebellitis or subacute cerebellar infarction.
The appearance may be mimicked by extensively nodular medulloblastoma (SHH molecular subgroup).
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