The Lhermitte-Duclos disease: a rare bilateral cerebellar location of a rare pathology

Dysplastic gangliocytoma or Lhermitte-Duclos disease is a rare disorder characterized by a slowly progressive unilateral tumour mass of the cerebellar cortex. It is probably hamartomatous, although the exact pathogenesis remains unknown. Lhermitte-Duclos disease was recently encountered to be part of a multiple hamartoma-neoplasia complex (Cowden's syndrome). It typically presents in young adults, although it has been encountered at all ages. We present the case of bilateral cerebellar location of this pathology in a 50-year-old man presented with a progressive onset and worsening of headaches accompanied by nuchal rigidity, photophobia and nausea awakening each morning. Upon physical examination, the patient was awake with a discrete right vestibular syndrome made of positive Romberg without nystagmus. Magnetic Resonance Imaging (MRI) was performed and revealed salient “tiger stripe” appearance of the bilateral cerebellar cortex relevant to a Lhermitte-Duclos disease.


Introduction
Dysplastic gangliocytoma or Lhermitte-Duclos disease is a rare disorder characterized by a slowly progressive unilateral tumour mass of the cerebellar cortex. It is probably hamartomatous, although the exact pathogenesis remains unknown. Lhermitte-Duclos disease was recently encountered to be part of a multiple hamartoma-neoplasia complex (Cowden's syndrome). It typically presents in young adults, although it has been encountered at all ages. Interestingly the genetics of childhood-onset appears different to the more common adult onset form.

Patient and observation
It is about a 50-year-old man with no particular medical history who was admitted for a progressive onset and worsening of headaches

Discussion
The Lhermitte-Duclos disease, or dysplastic cerebellar gangliocytoma, is an unusual tumour arising from the cerebellar cortex. It most frequently presents in the third and fourth decades of life [1,2] but the age at clinical manifestation ranges from birth [3] to the sixth decade [4]. There is no obvious sex preponderance. Regarding the nature of the disease, the original opinion expressed by Lhermitte and Duclos was that the tumour was a combination of a congenital malformation and a neoplasm arising from ganglion cells [5]. Other early observers of this entity suggested the lesion to be a "neurocystic blastoma" [2], "hamartoma" or "hyperplasia" [6]. Lhermitte and Duclos noted enlarged cerebellar folia containing circumscribed regions of abnormal ganglion cells [5]. They regarded the lesion as a combination of a ganglion cell neoplasm and a malformation originating from precursors of Purkinje cells. Bielschowsky and Simons suggested that the lesion is "an experiment of nature" derived from a local agenesis of the superficial cerebellar cortex, which resulted in a tumour composed of neuroblasts [2]. The histopathological differential diagnosis includes glioma, which might be confused with a very cellular dysplastic gangliocytoma and ganglion cell tumour [7]. with a high incidence of breast, thyroid and genitourinary malignancies [8]. Recently, thorough investigations support the contention that Lhermitte-Duclos disease and Cowden syndrome are part of a single spectrum best classified as a single phacomatosis [9].
Clinically, the duration of symptoms ranges from a few months to more than 10years [10]. Typically, the cause of clinical presentation is a posterior fossa mass lesion with headaches, cerebellar ataxia and visual disturbances and other cranial nerve palsies [1,9]. Signs and symptoms of increased intracranial pressure, such as headaches, nausea and vomiting, papilloedema, mental disturbances and loss of consciousness occur in a later stage of the disease caused by the progressive mass effect of the growing tumour [1,9]. MRI is certainly the imaging modality of choice today which shows a hypointense on T1-weighted images and show a very mild or no enhancement. The lack of contrast enhancement suggests insignificant disturbances of the blood-brain barrier and/or missing of extracellular oedema. On T2weighted images the lesions present with a well circumscribed high signal intensity and an unique striated pattern with isointense bands within the area of hyper intensity, indicating the structures of widened gyri and consequently displaced sulci of the cerebellar cortex [11].
Surgery is definitely the therapeutic procedure commonly performed for the treatment [1,9]. A sub-occipital approach is the surgical procedure generally performed [1,9] and additional permanent ventricular shunt drainage occasionally preceded or followed tumor resection [9]. The absence of tumor limits in the depth of the cerebellar hemisphere constitutes the major technical problem during Page number not for citation purposes 3 surgery. The radiation therapy should not be considered when in toto excision of the tumor and complete remission may be achieved [12].

Conclusion
Dysplastic gangliocytoma of the cerebellum is of benign behaviour and its incidence is extremely rare. Its origin is still debatable. This lesion is hypo intense on T1-and hyper intense on T2-weighted MRI.
Recognition of the disease is of particular importance, as the frequent but under-reported coexistence with Cowden syndrome, should prompt thorough clinical and apparative investigation to detect or exclude concomitant malignancies. for its collaboration.