venerdì 3 novembre 2006

Lhermitte-Duclos disease (LDD)


There is a well-defined lesion in the left cerebellar hemisphere, slightly hypointense to the brain parenchyma on T1-weighted images and slightly hyperintense on the T2 sequence (Figure 1 and Figure 2). Cerebellar folia are clearly demonstrated coursing through the lesion. There is no mass effect or surrounding edema. Minimal enhancement is seen on postcontrast administration (Figure 5).
The lesion is bright on diffusion-weighted images as well as on the ADC map (Figure 6 and Figure 7).

Diagnosis: Lhermitte-Duclos disease (LDD)

LDD, also known as dysplastic gangliocytoma of the cerebellum and granular cell hypertrophy, is a rare cerebellar mass lesion which has hamartomatous as well as neoplastic characteristics.
LDD may be sporadic or associated with Cowden disease, a rare autosomal dominant familial cancer syndrome with multiple manifestations, including trichilemmomas, diverse hamartomas, intestinal polyposis, palmoplantar keratoses, oral papillomatosis, and an increased predisposition to breast cancer and thyroid tumors.
Patients usually present as young adults with occipital headaches, ataxia and papilledema.
The lesions usually show unilateral cerebellar hemispheric involvement. CT demonstrates low-density cerebellar mass that may contain calcifications. There may be thinning of the ipsilateral occipital bone.
MRI shows the characteristic “striated” appearance with widened cerebellar folia. Striated pattern of hypointensity on T1-weighted imaging and hyperintensity on T2-weighted imaging alternates with isointense bands of tissue. Postcontrast enhancement is rare. No diffusion disturbance is seen on ADC maps. MR perfusion may show elevated rCBV.
The lesion shows elevated 18-FDG uptake on PET scans.
Mass effect by the lesion may cause hydrocephalus and tonsillar herniation. Surgery is typically required in cases of brainstem compression to reduce mass effect upon the fourth ventricle. Regrowth of the lesion following resection has been reported, so careful follow up is advisable.

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