Septum pellucidum hamartomas in neurofibromatosis type 1.

Septum pellucidum hamartomas have not been reported previously in neurofibromatosis type I (NF1). In a retrospective study of 86 cases with NF1 we found three patients with septum pellucidum hamartomas (frequency = 3.4 %). These could be detected on especially fluid attenuated inversion recovery and proton density-weighted images on MRI. With respect to proton spectroscopy in a patient. a low Cho level with a normal NAA peak was found, excluding a neoplasm. MR spectroscopy findings resulted in a very high NAA/Cho ratio (= 2.91). and a low Cho/Cr ratio (= 0.53) compared to a control group of 8 normal age-matched individuals. In this control group. mean NAA/Cho ratio was I .86. and mean Cho/ Cr ratio was 0.78.