The authors report a case of Lhermitte-Duclos disease, or dysplastic cerebellar gangliocytoma, in which a cutaneous sclerotic fibroma was found incidentally during the second resection of a recurrent cerebellar hamartoma. The association of Lhermitte-Duclos disease and sclerotic fibroma with Cowden's syndrome led to a dermatologic examination and confirmation of the diagnosis of Cowden's syndrome. The combination of both Lhermitte-Duclos disease and sclerotic fibroma with Cowden's syndrome has not previously been reported. A review of the 15 cases of Lhermitte-Duclos disease associated with Cowden's syndrome shows no significant gender predilection. Sclerotic fibromas, once thought to be specific for Cowden's syndrome, also are reviewed.