Figure 6a. Parahypothalamic hamartoma of the tuber cinereum in a 7-year-old boy with precocious puberty. Sagittal (a) and coronal (b) T1-weighted MR images show a well-defined, isointense pedunculated mass (arrow in a) in the characteristic location between the infundibular stalk anteriorly and the mamillary bodies posteriorly. The mass is attached to the floor of the hypothalamus by a narrow base (arrow in b) but does not lie within the substance of the hypothalamus. The diagnosis was confirmed at surgery.