Radiological Diagnosis

Lhermitte - Duclos Disease

 Lhermitte-Duclos disease ^{More Details} (LDD), a term used interchangeably to Dysplastic Cerebellar Gangliocytoma, is a rare disorder characterized by disordered cellular migration occurring during 2-5 months of intrauterine life[1]. A slowly progressive tumor like mass forms and replaces the normal architecture in the Cerebellum.The molecular layer is widened and consists of abnormal Ganglion cells, the Granular cell layer is hypertrophied while the Purkinje cells are absent[2]. These changes can be focal or diffuse.

The etiopathogenesis is still uncertain but germline mutations in tumor suppressor gene PTEN were found quite commonly in affected persons. The detected changes were Nonsense mutation at codon 130 (CGA ® TGA) and splice site mutations at the 5' site of Intron 4 and 3' site on Intron 8[3].

Association to Phakomatosis like Tuberous Sclerosis is spiculated[3] but the strongest link is the one with Cowden's Syndrome (Hamartoma-Neoplasia Complex)[1],[2],[3],[4]. According to some LDD might be a corollary of Cowden's syndrome .For this reason every patient of LDD should be screened for components of Cowden's syndrome like acral keratosis, Mucocutaneous lesions, Thyroid adenoma, Fibrocystic disease, Ovarian cysts, Intestinal polyposis, Arteriovenous malformation and bilateral breast tumors[1],[2],[5].

Clinical presentation maybe as delayed as in the third or fourth decade of life. Signs and symptoms may pertain to increased mass effect in the posterior fossa as gait disturbances, Tinitus, Cranial nerve palsy etc. These maybe associated with megalencephaly, polydactyly, hydrocephalus and orthostatic hypotension[1],[2].

M.R.I is the imaging modality of choice. T1W images show an illdefined, heterogenous, hypo or iso-intense lesion of varying size involving the cerebellum. Alternating to areas of hypointensity there are hyperintense areas known as 'Tiger - Stripped Appearance' .The lesion shows no significant contrast enhancement. On T2W and PDW sequences this lesion is heterogeneously hyperintense[1],[2]. The laminated pattern showing widened Cerebellar folia is very characteristic. C.T scan shows a hypo or iso-attenuating, non-enhancing lesion with mass effect.

M.R Spectroscopy shows increased level of Lactate and decreased levels of Myo-inositol, NAA and Choline[6]. P.E.T studies show a heterogeneous and discordant uptake of [(11) C] Met and [(18F)] FDG in various areas of the lesion suggesting that LDD is an actively evolving disease[7]. Treatment is by surgical decompression of the posterior fossa.