Lhermitte-Duclos disease (LDD), a disorder first described by French physicians Lhermitte and Duclos in 1920 [25], is a benign, slow growing dysplastic gangliocytoma of the cerebellum, characterized by replacement of the granule cell layer by abnormal granule and Purkinje like cells. The most frequent presenting signs and symptoms are megalocephaly, increased intracranial pressure, nausea, hydrocephalus, ataxia, gait abnormalities, and intermittent headaches, all of which are attributed to the mass effect [6,11,25]. Many cases are associated with a mutation in the phosphatase and tensin homolog or PTEN gene which is also involved in numerous otherwise unrelated central nervous system abnormalities, namely Cowden syndrome [1,6,11], autism spectrum disorder [18], cerebral cortical dysplasia [11,30] and Bannayan-Riley-Ruvalcaba syndrome [30]. The presence of cortical heterotopia has been reported in a small number of LDD cases [3,5,17,32]. We describe a unique case of LDD with cerebral cortical heterotopic grey matter containing neurofibrillary tangles.