FINAL DIAGNOSIS : Hypothalamic Hamartoma

They were said to have signal intensity similar to normal cortex on all sequences, this is in fact not true in most cases ⁷.

1. T1
   • hypointense to the cerebral cortex (74%) ⁷
2. T1 C+ (Gd): no contrast enhancement
3. T2
   • hyperintense to the cerebral cortex (93%) ⁷
   • hyperintensity is more conspicuous on FLAIR
   • the higher the proportion of glial cells, the higher the T2 signal ³
4. MR spectroscopy
   • reduced NAA/Cr
   • increased myoinositol ³
   • increased Cho/Cr compared to the amygdala has also been reported 

Delalande Classification of Hypothalamic Hamartomas

• Type I lesions have horizontal attachment inferior to floor of the third ventricle. 
• Type II lesions have vertical attachment to the wall of third ventricle and are above the floor of the third ventricle. 
• Type III lesions have horizontal and vertical attachments above and below the floor of the third ventricle. 
• Type IV lesions are considered “giant” with volume 8 cm³ or larger

The differential diagnosis is broadly that of suprasellar/hypothalamic lesions, although the imaging characteristics of hypothalamic hamartomas significantly reduce the differential.

Hypothalamic-chiasmatic glioma is the main differential. Most other lesions encountered in the region either have markedly different signal intensity or demonstrate enhancement.