HYPOTHALAMIC LESIONS

All images from this paper: http://www.ncbi.nlm.nih.gov/pubmed/17620469

Embryology: anterior pit from rathke's pouch (from mouth), posterior + infundibulum from neuroectoderm

Lesions:

Craniopharyngioma: 

adamantinomatous - childhood variant, very cystic, very heterogenous 

papillary - adult variant, smaller, more homogenous 

Germinoma

young kids, can have pituitary/pineal synchronous lesions, homogenous, enhancing, non-cystic/heterogenous 

Hamartoma

older kids, tuber cinereum, can be pedunculated or sessile (more likely to be assoc with gelastic seizures & precocious puberty if latter). These do NOT enhance. 

Dermoid Cyst

 well-circumscribed, ectodermal cysts of fat/sebaceous tissue/hair/etc. Typically T1 bright and suppress on STIR, but not as bright and not as suppressy as lipomas. Typically occur in the midline although not commonly at suprasellar. rarely enhance or have calcifications

Vs epidermoid cysts, which have the MRI appearance of dense CSF, more commonly appear off-center - esp parasellar 

Vs arachnoid cysts which look just like CSF because they are 

Rathke's Cleft Cyst

 well circumscribed, midline, between A&P pituitary, typically do not enhance/have calcifications

Hypothalamic/Chiasmatic glioma: 

 very often NF1 associated. larger tumors = more heterogenous, enhancing. 

Ganglioglioma

 very rare, well circumscribed, can be cystic, slow growing. 

Encephalitis 

 usually viral, with clinical evidence of infection 

LCH 

LCH - has unexplained predilection for pituitary stalk and infundibulum. hypothalamic lesions enhance. 

Sarcoid

nodular thickening of chiasm, stalk, infundiblum from granulomatous involvement of dura. predilection for skull base -- neurosarcoid often manifests around hypothal/pit. meningeal enhancement. can invade virchow-robin spaces.