Lhermitte–Duclos disease (dysplastic cerebellar gangliocytoma)

Abstract

Dear Editor, We read the article entitled “Cowden syndrome diagnosed by Lhermitte–Duclos disease” in the esteemed “Formosan Journal of Surgery” with great interest. Che Chen et al. reported a case of an adult female presenting with dizziness and headache. A brain magnetic resonance imaging (MRI) showed a cerebellar lesion, in which the histological findings were of dysplastic cerebellar gangliocytoma.[1] Lhermitte–Duclos disease (LDD), also known as dysplastic cerebellar gangliocytoma, is a rare genetic disorder, which is characterized by abnormal development of the cerebellum that can increase intracranial pressure. In this context, it could occur isolated or associated with Cowden syndrome. Moreover, this disease has some histological hallmarks such as thickening and hypermyelination of the outer molecular layer, loss of Purkinje cells and white matter, dysplastic ganglion cells with rounded nuclei, and abundant mitochondria invading the inner granular layer.[2] Here, we would like to highlight some important topics that together with the study of Che Chen et al. could lead to a better comprehension of LDD. In addition, we developed a mnemonic to remember the facts of LDD that is DUCLOS: Dysplastic cerebellar gangliocytoma; Unilateral hamartomatous mass with tigroid appearance on MRI; Cowden syndrome association; Later in life 3rd and 4th decades of life; Overpressure by the tumor leads to neurological symptoms; S uppressor gene PTEN mutation in at least 10% of the individuals.[123456] A recent genetic study about LDD was published by Colby et al. They reported a case of an adult female diagnosed with LDD and wild type for phosphatase and tensin homolog. When the exome sequencing was analyzed, it revealed an extracellular domain mutation in the epidermal growth factor receptor gene, which resulted in constitutive activation. Thus, this study was important because it supports a new hypothesis for the pathophysiology of LDD and contributes to a possible new therapy for the treatment of this disease.[4] In 2015, Bosemani et al. reported a case of pseudotumoral hemicerebellitis (PTHC) mimicking LDD in children, and they raised an important question asking about if neuroimaging can differentiate these two entities. A literature review revealed that conventional evaluation may help differ the diseases. Furthermore, they provide some features that if present are suggestive of LDD such as lesion-affecting brainstem, striated folial pattern, and thickened cerebellar folia surrounded by enlarged veins. Otherwise, if brain MRI has postgadolinium enhancement and a choline peak spectroscopy, PTHC could not be ruled out.[3] Zak et al. reported a case of LDD where surgical removal was not a possible option. Hence, a rapamycin trial based on a previous study about the pathological mechanism of LDD and the use of this medication was done. Rapamycin causes a downstream of some tissue growth factors that are associated with LDD. The infant reported in their study was diagnosed with LDD at 18 months, and rapamycin was started. On follow-up, the infant had full recovery including imaging that did not reveal the previous brainstem compression and distortion of pituitary stalk.[6] In another study, high-definition fiber tractography was done for surgical planning. Fernandes-Cabral et al. concluded that tractography is an important method that should be performed in surgical cases because it could reveal abnormalities not evident on conventional assessment. Therefore, this can allow maximal resection of the lesion, avoid damaging of unaffected tracts, and decrease tumoral recurrence.[5] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.