Although previous reports purpored that the unique magnetic resonance imaging (MRI) features of Lhermitte-Duclos disease (LDD) obviates the need for biopsy, we have made a misdiagnosis of LDD which has an indistinguishable imaging appearance. We present a patient who suffered from a normal cerebellum with arachnoid vascular malformation that had imaging characteristics which were indistinguishable from LDD before operation. This atypical imaging appearance, which could potentially be confused with LDD, may lead to misdiagnosis and inappropriate treatment in the absence of tissue sampling. Thus, this finding suggests that in those patients where images are highly suggestive of LDD but lack other manifestations of Cowden syndrome, biopsy is required and advanced imaging with magnetic resonance spectroscopy (MRS) should be strongly considered.