Late MR follow-up of hypothalamic hamartomas.

The absence of changes over time in the diagnostic features of suspected hypothalamic hamartomas is of paramount importance. Since magnetic resonance (MR) imaging is very sensitive to modifications in the brain parenchyma, a late MR follow-up study was performed in five children. In all cases, the diagnosis of hypothalamic hamartoma has been suspected on the basis of the association of central precocious puberty and the presence of a mass in the inferior aspect of the hypothalamus, demonstrated on previous MR studies. Late MR evaluation (after a mean of 39 months) demonstrated stability of the lesions in shape, size, and signal intensity. In three cases the lesions demonstrated a rim of isointense signal with a hyperintense center on T2-weighted sequences. In two cases a Chiari I malformation was found in association with the hypothalamic malformation. In one case a pineal cyst was demonstrated. These unusual findings are discussed. Late MR follow-up showed the absence of changes in the lesions over time, allowing the diagnosis to be confirmed.