We report a case of an 11-year-old patient who underwent CT imaging for complications of sinusitis, and showed incidental development of an interhemispheric cyst in association with an intracranial lipoma over a 10-year interval. Cysts and lipomas are well described in association with dysgenesis of the corpus callosum. We present an uncommon association, of a new cyst in association with an intracranial lipoma, in a patient with a normal corpus callosum.