Brain MRI findings of older patients with Pallister-Killian syndrome.

Pallister-Killian syndrome (PKS) is a disorder caused by a mosaic tetrasomy of chromosome 12p, which manifests with dysmorphism, intellectual disabilities, auditory disturbance, and epilepsy. Here, we describe the findings of brain magnetic resonance (MR) imaging in two patients with PKS. One patient, a 43-year-old man, showed multiple lesions with high signal intensity on T2-weighted image (WI) in the basal ganglia, and widespread T2 elongation in the periventricular white matter. The same signal change was also present in the pontine base. The other patient, a 37-year-old woman, showed T2-high lesions in the bilateral putamina and the parietal periventricular white matter. There was prominent atrophy of the cerebellum and brainstem in this latter case. Both cases showed cortical atrophy with frontal predominance, with accompanying dilatation of the lateral ventricles. Hypoplastic corpus callosum was also present in both cases. Cerebral atrophy with ventricular dilatation has been often described in PKS cases, but many of the MR findings in the present patients have never been reported. Such findings may appear with advancing age in PKS. Since 12p mosaicism is rarely detected in peripheral blood lymphocytes, examination of buccal mucosal cells with fluorescent in situ hybridization method is preferable for the diagnosis of PKS. Recognition of the characteristic features on cranial MR imaging, in addition to the characteristic facial appearance in adulthood, should prompt the correct diagnosis of adult PKS patients.